Biology Module 12

environmental impact of deforestation

You learned why humans cause deforestation and why forests are essential to life on Earth, but it's also important to understand why deforestation is a problem. Forests are complex ecosystems that are important to sustaining life. Destroying forests by deforestation can have some devastating consequences around the world. If you think about the reasons why forests are so important to living things and the functioning of ecosystems, you might be able to figure out why deforestation is an ongoing problem. In the left column, read the reasons why forests are important. Then jot down the effect of deforestation related to that particular reason. Click the text in the left column to see the answer. Importance of ForestsEffect of DeforestationSource of biodiversityLoss of biodiversity may lead to loss of some species. The loss, or extinction, of species can have devastating effects on other species, including humans.Absorbs greenhouse gases and produces oxygenMore greenhouse gases, like carbon dioxide, will enter the atmosphere. This can lead to global warming. Less oxygen will be released into the atmosphere, which animals use to breathe.Role in hydrologic cycleThere will be less trees to return water to the atmosphere through evaporation. Without the trees, the climate may become dryer. A change in climate may have a negative impact on some organisms.Prevent soil erosionWithout tree roots to anchor the soil, soil erosion is likely. With increased exposure to sun, the soil can dry out, leading to problems of increased flooding and eventually, an inability to farm the land. Question In general, why is deforestation a problem? Deforestation can contribute to global warming, soil erosion, loss of biodiversity, and a dryer climate.

causes of population growth

A population of over 6 billion people does not just happen. There must be reasons for this. Also, a population of over 6 billion people has to have a major impact on the environment. Before exploring the impacts on the environment, you need to understand why the population has become so large. Mortality refers to the number of deaths in a population over a period of time. Natality refers to the number of births in a population over a period of time. If mortality equals natality, a population remains stagnant. In other words, a population remains the same size if the birth rate and death rate are equal and no changes result from migration. At this point, humans are not migrating to other planets to live, so the birth rate and death rate must not be equal. The number of births is exceeding the number of deaths. What are some causes of this population increase? The graph below illustrates human population growth from about 10,000 years ago until the year 2000. Notice that there is no significant growth up until just 2,000 years ago. What do you think contributed to massive increases in the population beginning 2,000 years ago? Advancements in agriculture, technology, and medicine have contributed to dramatic increases in human population. In this century, the death rate in industrialized countries has declined sharply. In many of these countries, there has been a decline in the birth rate, resulting in a stable, but older population. In a few, the birth rate has dropped below the death rate, resulting in a shrinking population. In the underdeveloped countries, the birth rate remains very high. The death rate in most of the underdeveloped countries has dropped because of improved conditions. Therefore, the continued high birth rate is causing a rapid growth in these populations. People are living longer in both industrialized and developing countries. Click through the tabs to see how improvements in society have led to decreases in death rates in most countries. Medical Care Food Production Sanitation People have access to immunizations to prevent diseases, as well as to primary healthcare. Infant mortality has significantly decreased due to medical advancements. The development of new drugs for treatment of numerous diseases gives humans an advantage over infectious diseases. New surgical techniques in more recent decades have dramatically improved our chances for survival. Can you think of a group of drugs used to treat bacterial infections that caused a decrease in the human death rate? Antibiotics, like penicillin, treat and cure many different illnesses caused by bacteria. Question Why did the Industrial Revolution that began in the mid-1700s correspond to a huge increase in the human population? The Industrial Revolution profoundly affected life longevity by improving health, utilizing energy usage, and enhancing sanitation. Humans progressed from hunting and gathering to agricultural societies about 10,000 years ago. This has led to more efficient food production. We successfully farm livestock, produce, and seafood. In addition to advancements in agriculture giving humans access to more food, what is another benefit of this food? Better food production provides people with a larger amount of food and better nutrition. Improved sanitation practices have resulted in a decrease in the overall death rate. The creation and use of sewage and wastewater treatment plants make for a cleaner, healthier society. The production of clean drinking water is vital to peoples' health. How do you think garbage collection has improved life expectancy? If garbage is removed regularly, homes and other areas are kept cleaner and more sanitary. There is less chance of infestation by rats and insects, which means there is less chance of certain diseases.

Sources of greenhouse gases

After learning about the greenhouse effect, Karl wanted to understand the sources of these greenhouse gases. Natural processes have been introducing greenhouse gases into the atmosphere for billions of years. Since the Industrial Revolution started around the 1760s, human activities have also introduced greenhouse gases into the atmosphere. To get a complete idea of how these gases affect the average temperature on Earth, Karl had to explore both the natural and human sources of greenhouse gases. Click each tab to learn about the sources of greenhouse gases. Carbon Dioxide (CO2) Water Vapor Methane (CH4) Nitrous Oxide (N2O) Fluorinated Gases Both natural processes and human activities introduce carbon dioxide (shown by red arrows) into the atmosphere. The table below explains these natural processes and human activities. RespirationThis is a natural process used by all organisms to convert food energy to a more usable energy form, ATP. In addition to ATP, CO2 and water are produced.DecompositionThis natural process involves the breakdown of organic structures of dead organisms where some CO2 is released. Most of the CO2 of these dead organisms will be stored in the soil as rocks, such as limestone, or as fossil fuels, such as coal oil or natural gas. Dead organisms may also be consumed by other organisms, and CO2 is released through respiration. Volcanic ActivityIn this natural process, magma (stored molten rock) breaks through Earth's surface, releasing lava (flowing magma) and dissolved gases. Stored CO2 from decomposition is among the dissolved gases released during volcanic activity.CombustionThis is a human activity that involves the burning of fossil fuels in factories, cars, airplanes, and any other machine that uses fossil fuels. One of the results of combustion is releasing CO2.DeforestationIn this human activity, trees are cut down to clear land. Deforestation increases the amount of CO2 in three ways. First, when trees are cut, they release the stored CO2 they would have used for photosynthesis. Secondly, the burning of trees releases CO2. Lastly, trees remove CO2 from the atmosphere during photosynthesis. With fewer trees, less CO2 is taken out of the atmosphere.Cement ProductionThis is a human activity in which limestone is heated to make cement. This production releases CO2 into the atmosphere. What are the natural sources of atmospheric CO2? The natural sources of atmospheric CO2 are respiration, decomposition, and volcanic activity. Question Although most greenhouse gases have both natural and human sources, which greenhouse gases are only produced by human activity? Water vapor, shown in the image as white arrows, is introduced into the atmosphere through the natural processes of the water cycle. The majority of the atmospheric water vapor comes from the evaporation of bodies of water, such as rivers, lakes, and oceans. As the temperature increases, more water evaporates. Since the presence of water vapor in the atmosphere increases the temperature and causes more water to evaporate, this phenomenon is an example of positive feedback. In positive feedback, the effects of an action increase the effect. Although all organisms produce water as an end product of respiration, only animals with lungs breathe out some of this water as water vapor. Active volcanoes also release water vapor. How is atmospheric water vapor an example of positive feedback? As the amount of water vapor in the atmosphere increases, its presence increases the temperature, causing more water to evaporate. Both natural and human sources introduce methane into the atmosphere. The table below explains these sources. NaturalThere are several natural sources of atmospheric CH4. 1)Bacteria in wetlands, the ocean, and soil decompose dead organisms anaerobically (without oxygen), which releases CH4. 2)Termites (small wood-eating insects) release CH4 as part of their digestion, which is significant, given the size of their global population. 3) Volcanic activity and wildfires (the natural mass burning of trees) release methane. IndustryThis human activity not only releases CH4 through the combustion of natural gas, but also through the production, storage, and distribution of natural gas as well.AgricultureThe digestion process of livestock, such as cattle, buffalo, sheep, goats, and camels, releases CH4, especially when their manure (feces) is stored in a manure lagoon (an artificial lake filled with feces), where anaerobic decomposition occurs. This is considered a human source since the livestock are controlled by people.LandfillAnaerobic bacteria decompose wastewater in a treatment facility. This is considered a human source since the waste management is controlled by people. Although anaerobic bacteria decompose wastes in agriculture and landfills, why are these phenomena considered human sources? They are considered human sources because humans raise livestock and control landfills. NaturalCertain decomposing bacteria release N2O from animal wastes by denitrification (a process that removes nitrogen products from a substance). IndustryThe release of N2O occurs when synthetic (manmade chemicals) materials, such as fertilizer and nylon (a synthetic fiber), are made.AgricultureDenitrifying bacteria decompose livestock manure and urine, releasing N2O. Nitrous oxide is also released when synthetic fertilizer is used to grow crops.TransportationMotor vehicles, especially trucks, release N2O during the combustion of fossil fuels. The amount of N2O released depends on the type of fuel, engine design, engine maintenance, and operating practices. What role do bacteria play in the release of N2O? Denitrifying bacteria decompose animal wastes. Fluorinated gases are chemicals that contain the element fluorine. They are the only greenhouse gases that are made by humans. The three main classes of fluorinated gases (F-gases) and their uses are shown below. Hydrofluorocarbons (HFCs)HFCs are used as refrigerants (chemicals that cool things down), aerosol propellants (gases that force other substances out of a spray can), solvents (a substance that dissolves another substance), and fire retardants (a substance that reduces a materials flammability or combustion). HFCs replaced both CFCs(chlorofluorocarbons) and HCFCs (hydrochlorofluorocarbons). CFCs and HCFCs destroyed the ozone layer (a gas made of O3 that blocked most of the sun's powerful, damaging ultraviolet energy.)Perfluorocarbons (PFCs)PFCs are a by-product in processing aluminum and making semiconductors,which are parts of electrical circuits.Sulfur hexafluoride (SF6)SF6 is used to process magnesium, make semiconductors, and detect gas leaks due to its bad smell. Which environmental problem motivated the creation and use of HFCs? HFCs were created to replace CFCs and HCFCs, which destroyed the protective ozone layer.

Controlling Greenhouse Gases

Now that Karl understood the consequences of the enhanced greenhouse effect, he was more motivated than ever to educate his school community about what they could do to minimize the total amount of greenhouse gases introduced into the atmosphere. Since the most abundant greenhouse gas is carbon dioxide, Karl put together a top ten list of things people could do to lessen their personal introduction of atmospheric CO2, which is also known as lowering one's carbon footprint. Watch this slideshow to see Karl's top ten list of ways to lower one's carbon footprint. Limit Greenhouse Gases Be an active citizen by voting for government officials who will support laws that limit the production of greenhouse gases. How can voting lower your carbon footprint? You lower your carbon footprint by voting for officials who will support measures that limit the production of greenhouse gases. Question What are the two main goals for all the tips for lowering your carbon footprint? The two main goals for all the tips are to use less energy and reduce carbon dioxide production. Search for an energy supplier that generates at least half of its power from renewable sources. A renewable energy source is replaced through natural processes and includes wind, solar, and other clean sources. This reduces the use of fossil fuels. How can choosing renewable energy lower your carbon footprint? Using renewable energy reduces the use of fossil fuels.Buy a carbon offset to balance how much CO2 you produce during your daily activities. A carbon offset is a project, such as wind farms or methane recapture, that reduces greenhouse gases. How can offsetting carbon lower your carbon footprint? You lower your carbon footprint by investing money in projects that reduce the amount of greenhouse gases. Buy an energy efficient car like a hybrid (a vehicle that uses two or more different sources of power). Hybrid cars run mostly off electricity and use less gasoline, a fossil fuel. How can buying a hybrid car lower your carbon footprint? They use less gasoline. Keep tires inflated to correct air pressure so the engine does not have to work as hard to move the car. Also, have the car tuned up and change the air filter regularly to maintain the engine's efficiency. An efficient engine uses less gasoline. How can changing your car's air filter lower your carbon footprint? You lower your carbon footprint by maintaining the efficiency of the car's engine. Have insulation installed in your home to keep the cool air inside during the summer and the hot air inside during the winter. Sealing cracks also stops drafts. Cooling and heating accounts for 40% of a home's energy use. Weatherizing (using insulation and sealing) reduces the amount of energy to heat and cool a home. How can installing insulation lower your carbon footprint? It reduces the amount of energy used to heat and cool a home. Purchase energy-efficient appliances since they use less energy. Appliances, such refrigerators, washers, dryers, water heaters, and dishwashers, are now designed to use less energy. How can buying energy-efficient appliances lower your carbon footprint? They use less energy. Replace incandescent bulbs with compact fluorescent bulbs, which last ten times longer, use less energy, and lower CO2 production. How can using compact fluorescent bulbs lower your carbon footprint? Compact fluorescent bulbs use less energy and lower the production of CO2. Use public transportation, ride a bike, walk, and/or carpool. Also, group your tasks to make fewer trips. All of these transportation alternatives lower the demand for fossil fuels and lower air pollution. How can driving less lower your carbon footprint? Driving less decreases the demand for fossil fuels. Move to a smart growth community where residents live close to where they work and close to services, such as medical clinics, grocery stores, and libraries. These places also have public transportation. Less individual driving reduces air pollution and uses less energy. How can living in a smart community lower your carbon footprint? You lower your carbon footprint by living closer to where you work and shop and by using public transportation.

causes of water pollution

Now that you are familiar with the different types of water pollution, let's focus on the source of the pollutants. Some sources discharge numerous types of pollution into the water. Bodies of water are polluted by businesses, farms, households, and in some cases, nature itself. Click the tabs below to learn about the various causes of water pollution. As you read, think about where these pollutants are coming from. Industries, Factories, and Businesses Agriculture Households Natural Causes Industries, factories, and businesses generate a huge amount of water pollution. The clearing of land can lead to erosion of soil into rivers, resulting in suspended matter pollution. Waste and sewage generated by industry can also get into the water supply, resulting in nutrient and chemical pollutants in waterways. What is a possible result of nutrient pollution in a lake? Eutrophication occurs when the presence of nutrients causes excessive growth of algae or weeds. Question In general, what are the causes of water pollution? Water pollution can be caused by industries, agriculture, households, and nature. These sources of pollution can release microbiological, chemical, suspended matter, nutrient, oil, and garbage into waterways. Farms often use large amounts of herbicides and pesticides, both of which are toxic pollutants that lead to chemical and nutrient pollution. Herbicides are used to control weed growth, and pesticides are used to control insect populations that feed on crops. These chemicals are particularly dangerous to life in smaller rivers, streams, and lakes where a large variety of organisms live. As pictured in this image, farmers also frequently spray large amounts of chemical fertilizers onto their crops, and this fertilizer can be washed into the waterways and damage the water supply, as well as the life within it. Fertilizers can increase the amount of nitrates and phosphates in the water, which can lead to the process of eutrophication. Also, a large amount of suspended matter pollution occurs due to the exposed soil of agricultural fields running off into bodies of water. Excessive amounts of soil in water can block sunlight and clog the gills of fish. If sunlight is blocked, what may happen to plants that live in the waterways? Plants require sunlight to perform the process of photosynthesis. If they cannot photosynthesize to make their own food, the plants will die. Sewage generated by households introduces nutrients into nearby waterways that can cause eutrophication. Fertilizers, herbicides, and pesticides used for lawn care can run off and cause chemical and nutrient pollution. As with agricultural fertilizers, home fertilizers can lead to the eutrophication of lakes and rivers. Improper disposal of hazardous chemicals down the drain introduce toxic chemicals into the ecosystem, contaminating the water supplies in a way that can harm aquatic organisms. Leaks of oil and antifreeze from a car on a driveway can be washed off by the rain into nearby waterways, polluting them. Can you think of another type of pollution generated by common households that may end up in waterways? Garbage can end up in nearby waterways if it isn't properly disposed of, as shown here. In some cases, humans are not the source of water pollution. Nature can cause both suspended matter and microbiological pollution. Some bodies of water contain naturally high amounts of microorganisms that can be harmful to humans if they drink the untreated water. Natural events, such as volcanic eruptions or landslides, can also cause water pollution. What type of pollution may result from a volcanic eruption or landslide? Excess soil and rocks fall into waterways, creating suspended matter pollution. Question In general, what are the causes of water pollution?

importance of forests

Temperate birch forest in winter.Australian rainforest. Forests are spread over about 30% of Earth's land surface, and there are different types of forests. Broadleaf forests, sometimes called temperate forests, are located in areas with hot summers and cold winters. They have common tree types of oak, maple, and birch. Tropical rainforests are located in areas near the equator with a warm and wet climate and dense tree cover. No matter what type of forest, these habitats are vital to the functioning of natural ecosystems. What is an ecosystem? An ecosystem contains populations of organisms, as well as the physical environment it occupies. Why are forests so important to ecosystems? Click the tabs below to see some of the reasons forests are so important. Source of Biodiversity Greenhouse Gases and Oxygen Role in Hydrologic Cycle Soil Erosion Grey wolf living in a temperate forest. Think about all the different types of critters living among the trees in a forest. Approximately 70% of Earth's plant and animal species live within forest habitats. Thus, forests contain the greatest amount of biodiversity. Remember that all species within an environment are related to one another in some way. The success of one species depends on another. Think about food chains, for example. A species of bird may live in the treetops and feed on a species of beetle that lives on the tree trunks. Both of these species are dependent on each other, as well as on the trees in the forest. The forest supplies living things with a habitat, or a place to live. What does the term biodiversity mean? Biodiversity is the variety of living species on Earth. Forests contain a massive amount of biodiversity. Question You now know some of the reasons forests are important to ecosystems. Why are forests important to humans? Humans use the products of forests, such as wood for building structures and paper products. Humans also use the land that forests occupy for farming or a place to live. Forests play a critical role in absorbing greenhouse gases that fuel global warming. Greenhouse gases trap heat within the atmosphere. Excess greenhouse gases, such as carbon dioxide, may contribute to global warming. Trees absorb carbon dioxide and use this gas to produce their own food during photosynthesis. During this process, trees produce oxygen. Most organisms on Earth require oxygen to live. Earth contains a limited amount of water. As outlined in this image, the hydrologic cycle, also known as the water cycle, is the journey water takes as it circulates from the land to the sky and back again. Trees contain a large amount of water in their trunks and leaves. Notice the arrow in the image pointing from the trees up to a cloud. Trees help perpetuate the water cycle by returning water vapor back into the atmosphere. They do this when excess water evaporates from their leaves. What happens when water vapor is returned to the atmosphere? Precipitation, such as rain and snow, occurs. Water continues to cycle through the environment with the help of trees. Soil erosion means the soil does not stay in place, but washes away. Tree roots anchor the soil. By blocking out sunlight, treetops (called a canopy) prevent soil from drying out. Forests help prevent flooding by keeping the soil moist so that it does not dry out and get washed away during heavy rains.

Enviornmental Impact

The problem of human population growth affects everyone and everything in the environment. Scientists believe that eventually Earth will reach its carrying capacity, and human population size will stop increasing. As of now, it continues to increase. That means we continue to need more and more necessities like food, drinking water, and shelter. As humans take these natural resources, the environment pays the cost. Most developed economies currently consume resources much faster than they can regenerate them. Most developing countries with rapid population growth face the urgent need to improve living standards. As humans exploit nature to meet present needs, are we destroying resources needed for the future? View the slideshow to understand how our explosive population growth negatively impacts our environment. Increased Pollution Pollution is the introduction of contaminants into the natural environment that cause adverse change. Gaseous wastes from cars and trucks, the burning of fossil fuels, and industrial gases have polluted the air. Sewage and industrial wastes dumped into streams and rivers have polluted the waterways. The land has been polluted by tremendous quantities of solid wastes generated by industry and by the population in general. What are some examples of fossil fuels? Fossil fuels include coal, oil, and natural gas. Many scientists believe that if the global temperature rises as projected, sea levels will rise by several meters, causing widespread flooding. This phenomenon is referred to as global warming. Global warming also could cause droughts and disrupt agriculture. Question In general, how does human population growth affect the planet? More humans mean more pollution, more greenhouse gas emissions, destruction of habitats such as coastlines and oceans, and decreased biodiversity. Deforestation refers to the destruction of natural forests. Forests are destroyed to clear land for farming or development. Nearly half of the world's original forest cover has been lost, and each year more are cut down, bulldozed, or burned. Forests are vital to maintaining healthy ecosystems. What else do humans use the products of deforestation for? They are used for wood for building materials. Many natural ecosystems are pressured by high population densities and urban development. As more people need space to live, the population expands into natural areas that were once untouched. Coastal ecosystems and oceans are also negatively affected by human population growth. For example, a tide of pollution is rising in the world's seas. Ocean fisheries are being overexploited, and fish catches are down. This means that humans are catching more fish faster than the fish can reproduce. Biodiversity is the variety of life on Earth. Earth's biological diversity is crucial to the continued success of agriculture and medicine--and perhaps even to life itself. Think of all the different species in remote rainforests. Maybe these habitats contain an undiscovered plant species that can cure a particular disease. Yet human activities are pushing many thousands of plant and animal species into extinction. Two of every three species is estimated to be in decline. A specific type of beetle became extinct due to its loss of habitat. What do you think would happen to the toads that used these beetles as their food source? The toads may become extinct also. If one organism in a food chain becomes extinct, this affects all other living things in the environment. Greenhouse gases, such as carbon dioxide, methane, and nitrous oxide, trap heat and make the planet warmer. Human activities are responsible for almost all of the increase in greenhouse gases in the atmosphere over the last 150 years. What do you think is the largest source of greenhouse gas emissions from human activities in the United States? Burning fossil fuels for electricity, heat, and transportation are the largest source of greenhouse gas emissions.

Cause and effect of air pollution

This pie chart represents the primary air pollutants in the United States. Notice the two categories of air pollutants that are included. Particulate matter, or aerosols, comprise 36% of the total pollutants, while the remaining 64% are gaseous emissions. Notice that carbon monoxide gas makes up the majority of air pollutants (38%). Click the tabs below to find out more about some of the most common air pollutants. As your read, identify the source or cause of each pollutant (where it comes from) and the effect it has on the environment. Carbon Monoxide (CO) Particulate Matter Volatile Organic Compounds (VOCs) Nitrogen Oxides(NO, NO2) Sulfur Dioxide (SO2) Carbon monoxide is a gaseous emission produced by the burning of gasoline, coal, and oil. The exhaust coming out of a car engine, as shown here, releases this pollutant. You may have heard of carbon monoxide poisoning. This colorless, odorless gas binds to the hemoglobin in the red blood cells in the body and interferes with the transport of a vital molecule. What is this vital molecule that is transported through the blood by the red blood cells? It's oxygen. Carbon monoxide readily binds with the hemoglobin in the red blood cells, which prevents oxygen from binding to the hemoglobin. If oxygen cannot bind to the hemoglobin, then it cannot be transported throughout the body. Normally carbon monoxide poisoning occurs in areas that are not well ventilated or have little air flow, such as a closed garage. If a person breathes in this gas long enough, it can result in death. Carbon monoxide that is released into the atmosphere can react with other chemicals, contributing to the production of greenhouse gases. Remember that greenhouse gases, such as carbon dioxide, methane, and nitrous oxide, trap heat within the atmosphere. Recall that excessive greenhouse gases in the atmosphere may result in global warming. Question Did you notice a trend in the causes of air pollution? Who is responsible for releasing pollutants into the air? By driving vehicles, operating factories, and generating power, we release pollutants into the air. Particulate matter, or aerosols, are released by the burning of wood, diesel, and other fuels. These tiny particles are also released through industrial and agricultural processes. For example, plowing and field burning can release aerosols into the air. These air pollutants can irritate the eyes, nose, and throat, and can cause lung damage. In the environment, a visible haze can reduce visibility. Ashes, smoke, soot, and dust can soil and discolor structures and property. How does particulate matter affect sunlight? The tiny particles in the atmosphere scatter sunlight and reduce the amount of light reaching the earth's surface. Volatile organic compounds, or VOCs, include certain hydrocarbons, a group of compounds that contain the elements hydrogen and carbon. These gaseous emissions are also produced by the burning of gasoline, coal, oil, natural gas, and wood. Several hydrocarbons, such as formaldehyde and acetaldehyde, result from the use of certain paints and solvents. Spray paint usually contains a high amount of VOCs. These pollutants can irritate the eyes, nose , and throat. Some VOCs can react with other pollutants in the presence of sunlight to form what is known as photochemical smog, the type of smog found in Los Angeles. What are some effects of this smog? Smog lowers visibility and is highly irritating to the eyes and lungs. Nitrogen oxide (NO) and nitrogen dioxide (NO2) are gaseous emissions produced by the burning of some fossil fuels. Reactions in the atmosphere between NO, oxygen, and sunlight produce ozone (O2) which can also be a pollutant. This can also give rise to smog effects and health problems related to eye and lung irritation. When NO2 is exposed to sunlight, it turns a dirty brownish color. NO2 can react with other pollutants and may lead to the formation of acid rain, which results when acidic pollutants are dissolved in rainwater. Acid rain can damage buildings, monuments, and trees. Increasing AcidityNeutralIncreasing Alkalinity pH is a measure of the acidity or alkalinity of a solution. As shown in the image of the pH scale above, if a substance has a pH of less than 7, it is an acid. If it has a pH greater than 7 it is a base, or alkaline. Acid rain can be harmful to the organisms in lakes and soils. For most organisms, living in a "neutral" environment is optimal. If the pH of their environment drops too low (becomes too acidic), the organisms may not be able to function properly. Acid can burn through cell membranes in tiny organisms. In some cases, death occurs. Sulfur dioxide is a gaseous emission produced by the burning of coal and oil that contain sulfur. This image shows a power plant that burns coal. In the atmosphere, sulfur dioxide reacts chemically to form sulfuric acid, a harsh irritant to the respiratory system. Sulfuric acid can irritate the neutral linings of the nose, mouth, and throat, causing a burning sensation. If it reaches the lungs, damage can occur. If sulfuric acid dissolves in rainwater, what may result? Acid rain is formed.

Damage to coral reefs

Velma had not realized that such a diversity of organisms lived in a coral reef ecosystem. She loved learning about the mutualistic relationship between the corals and zooxanthellae. She also marveled at how the exoskeleton provides protection and support for the coral and a living space for fish. When she asked the guide what were the biggest threats to coral reefs, he answered, "People." Watch this slideshow to learn about the causes of coral reef damage. Careless Tourism Snorkeling above a coral reef. Some tourists visit coral reefs and damage it with their careless actions. Touching the reef, collecting corals for a souvenir, and dropping anchors on top of the reef all cause damage. Even indirect actions, such as stirring up sediments, affect the corals since the algae growing on top of the corals need clear water to photosynthesize. Question What are the most common ways people's actions damage coral reefs? People damage coral reefs through careless tourism, destructive fishing practices, pollution, coral mining, and climate change. Some unethical fishermen use destructive fishing practices, such as using dynamite to kill a large amount of fish. This sometimes causes damage to the reef as well. These fishermen may also use poison, such as cyanide, to stun fish before capturing them in a net. Not only are such practices destructive to the ecosystem, but they lead to overfishing. With a lower population of coral reef fish that eat the algae, the corals are choked out by excessive algal growth and die. Unfortunately, there are many sources of pollution from human activities. Some pollutants, such as oil spills, poison organisms and block sunlight. Runoff from land can contain silt (a fine grained sediment) that blocks sunlight and possibly fertilizer that encourages an overproduction of algal growth. Runoff may also contain pesticides (poison used to kill organisms harmful to plants and livestock), which may poison coral reef organisms as well. Another source of pollution is trash, especially plastics like bags and bottles. Trash blocks sunlight and smothers the coral. How does trash smother the coral? Trash blocks the corals' access to oxygen. Corals are mined for their limestone exoskeletons. The exoskeletons are used in the construction of buildings and roads, as calcium supplements, souvenirs, jewelry, personal marine aquariums, and medical bone graft trials. Using coral exoskeletons for bone grafting is a new technique that helps broken bones heal faster. In the past, bone grafts used artificial material, but it did not break down and allow a person's natural bone material to replace it. Coral exoskeletons, on the other hand, provide temporary support until the person's natural bone material grows and replaces the graft. Climate change is caused by an excess of greenhouse gases, which are atmospheric gases (especially carbon dioxide--CO2) that trap and distribute the sun's heat. These gases are produced by burning fossil fuels. Some of the excess CO2 is absorbed in the ocean, causing the marine water to become more acidic. This excess CO2 in the water is incorporated into coral exoskeletons. As a result, their exoskeletons are more fragile, which means they are not as well protected. Some of the excess CO2 is absorbed in the atmosphere, which increases the average global temperature. When corals become too hot, they become stressed and expel (get rid of) their zooxanthellae, without which the corals appear white. This phenomena is known as bleaching and often leads to the death of the coral because of the loss of nutrients due to the absence of zooxanthellae. How does climate change affect coral reefs? Climate change affects coral reefs by making marine waters more acidic, which weakens their exoskeletons; climate change also causes bleaching.

Types of water pollution

Water pollution is the contamination (usually by human activities) of oceans, lakes, rivers, streams, and drinking water. Recall that the human population continues to increase. With more people comes more pollution both in the air and in the water. Because there are many sources of water on Earth, there are many different types of water pollution. Some of the pollutants that contaminate air affect water as well. For example, acid rain falling into lakes and rivers causes water pollution. What is acid rain? Acid rain occurs when acidic chemicals in the atmosphere dissolve in rainwater. When it rains, acids then rain down into the environment. Water pollutants aren't just chemicals falling from the sky, though. Click through the slides below to get an overview of some of the major types of water pollution. Nutrient Pollution Nutrient pollution can result in eutrophication. This occurs when a lake or river has pollutants containing nutrients or organic wastes. These nutrients increase algae and plant growth in the water. Some wastewater, fertilizers, and sewage contain high levels of nutrients. For example, many fertilizers contain high levels of nitrogen. When fertilizers are washed into nearby lakes by rainfall or irrigation, nitrogen in the lake encourages the excessive growth of algae, resulting in eutrophication. Wastewater is water that goes down the drain in your sink and shower or washing machine. Sewage is a type of wastewater that is flushed down the toilet. If wastewater ends up in bodies of water, it encourages algae and weed growth. This will make the water undrinkable. Too much algae will also use up all the oxygen in the water. What can happen to other organisms if algae use up all the oxygen in the water? They will die out of oxygen starvation. Fish and invertebrates require oxygen to carry out their life processes. Question Which type of pollution is acid rain? Acid rain is an example of chemical pollution. Acids are chemicals with a low pH that can cause damage to aquatic ecosystems. In many communities in the world, people drink untreated water (straight from a river or stream). Sometimes there is natural pollution caused by microorganisms like viruses, bacteria, and protozoa. This natural pollution can cause fish and other aquatic life to die. What can happen to humans who drink water contaminated with microorganisms? This may cause serious illness, maybe even death, to humans who drink such waters. Many industries and farmers work with chemicals that end up in water. These include chemicals that are used to control weeds, insects, and pests. Metals, such as lead and mercury, and solvents containing hazardous chemicals from industries can pollute water bodies. These are poisonous to many forms of aquatic life and may slow their development, make them infertile, and/or kill them. What does infertile mean? It means an animal is unable to reproduce. Some pollutants (substances, particles, and sediments) do not easily dissolve in water. This kind of material is called particulate matter. If excess dirt or soil is washed into a river, the sediment could block out sunlight, causing the death of water plants and photosynthetic algae. Remember that photosynthetic organisms require sunlight to make their own food. In the water, tiny particles that do not dissolve later settle to the bottom. These particles, or sediments, that do not dissolve in water are called suspended matter. They can harm and even kill aquatic life that live at the bottom of water bodies. Thinking back to air pollution, what is another name for particulate matter pollution in the air? They are called aerosols. Oil spills usually only have a localized effect on wildlife, but they can spread for miles due to wind and water currents. The oil can cause the death of many fish, as well as get stuck to the feathers of seabirds, causing them to lose their ability to fly. This was one of the devastating effects of the BP oil spill in 2010. What other sea animals are affected by oil spills? Sea turtles and shellfish (oysters, shrimp, crab) are all affected by oil spills. Paper waste, food waste, plastic, rubber, and metallic and aluminum waste are examples of garbage and rubbish that can end up polluting waterways. In some countries, garbage is deposited in the sea. All these waste types take time to decompose. For example, it is known that paper takes about 6 weeks, aluminum takes about 200 years, and glass takes even longer to decompose. When these end up in the sea, they harm sea animals and cause a lot of water animal deaths. What if a large fish mistakenly ate an aluminum can thinking it was food? The can could do damage to the fish's internal organs and cause death.

water pollution control

You should now have a better understanding of the causes of water pollution and how it affects the environment. But how is water pollution controlled? Dealing with water pollution is something that everyone, including individuals and governments, needs to get involved with. Learning about the issue like you are doing right now is the greatest and most important step to take. Click the slides below that give evidence of how water pollution is being controlled. Government Control Many governments have very strict laws that help minimize water pollution. These laws are usually directed at areas such as industries, hospitals, and schools. They focus on how to dispose, treat, and manage sewage. In many developed cities, sewage treatment is very efficient, and it is designed to minimize pollution of water bodies. Just like the clean air acts were established to increase awareness of and reduce air pollution, the U.S. government has also created clean water acts to do the same thing with water pollution. Passed in 1972, the Clean Water Act is the primary federal law in the United States governing water pollution. Hefty fines and actions for industries that do not comply with water pollution prevention laws help reduce the amount of water pollution. If industries know that they are being monitored and checked regularly, do you think they would be more likely to follow the imposed laws? Yes, if industries know they are being watched, they usually try to ensure best practices of waste and chemical dumping at all cost. Question Can you cite evidence of how water pollution is being controlled? The Clean Water Act passed in 1972 makes sure industries properly manage their sewage to decrease water pollution. Water recycling programs use wastewater to irrigate fields. Water conservation and responsible consuming also help control water pollution. Another practice for reducing water pollution is water recycling. This involves taking wastewater (water from toilets, sinks, washing machines, etc.) and re-treating it so that it can be used for water uses such as field irrigation. For example, the water that goes down the drain in your house could be treated and then come out of sprinkler systems (as shown here) at your school. This leads to less water being wasted; thus, less water needs to be removed from the delicate ecosystems where aquatic life is already threatened by other factors. Water conservation is the practice of saving and not wasting water. Conserving water as not only a natural resource, but as a habitat, is an important part to controlling pollution. By practicing water conservation, there is less wastewater made to run off into natural habitats. There is also more clean, fresh water left in those habitats. This is an easy way to help control water pollution. How can you conserve water at home? Do not keep the tap running when you're not using it. Also, reduce the amount of water you use when washing things or when bathing. Being a responsible consumer is very helpful in the fight against water pollution. Personally accepting the responsibility to dispose of chemicals properly instead of pouring them in sewer drains and only purchasing non-hazardous materials goes a long way in the fight against water pollution. There are numerous environmentally friendly or natural cleaning products available to consumers now.

non renewable energy

"Practically every environmental problem we have can be traced to our addiction to fossil fuels. . . ." --Dennis Weaver Dennis Weaver was an actor and devoted environmentalist who wanted to protect and clean up the environment. Weaver spoke out against America's addiction to fossil fuels, but what are the destructive fuels he was referring to? And what do you think he means by "addiction"? Fossil fuels are the primary sources of energy that we use daily to generate electricity, drive cars, and cook food. You could say that we are "addicted" to these fuels because we use them for so many activities in life. Most people rarely even think about what happens to the environment when we use fossil fuels. Fossils are the remains of organisms that once lived. Fossils fuels formed from the remains of dead organisms deep underground, which is why these energy sources are called fossil fuels. Fossil fuels are nonrenewable energy sources, meaning they cannot be reused over and over again. Once the fossil fuel is burned, it is used up. Question What are the three types of fossil fuels? The three types of fossil fuels are oil, coal, and natural gas.

Hydropower

Along with both solar and wind power, hydropower is a renewable source of energy. Hydro- means "water," so this energy source relies on flowing or falling water. It is one of the older electricity generating technologies around. Like wind power, electricity can be generated by the conversion of the kinetic energy in fast-flowing water. Hydropower is the most widely used source of renewable energy. You may be aware of the Hoover Dam on the Colorado River, shown here. It contains a large power plant used to generate electricity through hydropower. Click through these tabs to learn how hydropower works, as well as the advantages and disadvantages of this alternate energy source. How Hydropower Works Advantages of Hydropower Disadvantages of Hydropower Typically, a flowing river, stream, or canal is blocked by a dam at a certain point with the intention of holding the water back and storing it in a reservoir. The weight of the water that is held by the dam increases to a certain level and is then released by opening the gates of the dam. The high pressure water flowing downwards ("flowing water" in image) is used to turn a series of blades in a turbine. The high pressure of the water rotates the turbine, which is connected to an electricity generator by a shaft (a metal tube). Then the energy is sent through the shaft to the generator. Electricity is generated and sent to the power station where it is transferred to homes and industries. What is created by wires and magnets in a generator that creates electricity? A magnetic field is produced by coiled wires attached to magnets as blades in a turbine rotate. Hydropower is a reliable, renewable energy source that produces no greenhouse gases that contribute to global warming. It also produces no pollutants during the energy generation process. Hydropower plants, like this one, are capable of producing large amounts of energy. Dams, like the one shown here, for hydropower plants are very expensive to build. They can also be affected by droughts. If there is less water in the dam's reservoir, less energy will be generated. Also, dams can have negative impacts on the environment. Organisms can be affected if their habitat is changed by the construction of a dam.

Consequences of overpopulation

An explosive human population is a direct result of more effective medical care, food production, and better sanitation. These same advances in technology may be leading to human overpopulation. If overpopulation does occur, how will this impact the environment? In other words, what are the future threats of overpopulation? You may have learned about the impacts of population growth on Earth. Take a look at this slideshow to review those impacts and learn about future threats of overpopulation. Each slide includes a description of a specific impact. See if you can describe possible consequences of this impact if Earth is overpopulated. Then click the button to reveal the answer. Increased Pollution An increase in contaminants released into the natural environment causes adverse change. Overpopulation would cause an even greater increase in air, water, and land pollution. More people means more pollution. Population growth in both industrialized and developing nations is greatly stressing the environment. If the growth rate is not reduced and overpopulation becomes a reality for the planet as a whole, many ecosystems will be permanently destroyed. At that point only an increased death rate will keep the human population within its carrying capacity. Question What are the future threats of overpopulation? Overpopulation could cause greater increases in pollution, global warming, and deforestation. It may also lead to massive decreases in biodiversity, as well as the destruction of habitats. More people equals more environmental issues. Forests are destroyed to clear land for farming or development. Overpopulation would cause more deforestation. More healthy ecosystems would be affected by the loss of trees. Ocean and coastline habitats are pressured by high population densities and urban development. Overpopulation would increase the need for food sources (seafood) and new places to live, thereby destroying more aquatic ecosystems. Species can become extinct, which leads to decreased biodiversity. Overpopulation means more people need space to live. The population would expand more into natural areas that were once untouched, leading to an even greater decrease in biodiversity. Greenhouse gases, such as carbon dioxide, trap heat and make the planet warmer. Overpopulation would mean an even bigger increase in greenhouse gas production leading to more rapid global warming.

Aerosols & Gases

An increase in human population growth negatively impacts our world. With an increase in population comes an increase in air pollution. More specifically, air pollution is a problem in industrialized countries with large urban populations and many cars. Gaseous wastes from cars and trucks, the burning of fossil fuels, and industrial gases have polluted the air. In the United States alone, more than 200 million metric tons of pollutants are released into the atmosphere each year. Most air pollutants can be placed into one of two categories. Click through these tabs to learn more about them. Aerosols Gases A busy construction site stirs up dust, creating a cloud of aerosol pollution. Aerosols are sometimes called particulate matter. They consist of tiny solid particles or liquid droplets that remain suspended in the air. Dust, smoke, and soot are all examples of aerosols. These particles are released during industrial, agricultural, or other activities. They scatter sunlight, reducing the amount of light reaching the earth's surface. If aerosols reduce the amount of light reaching the surface, how might this affect the temperature? Aerosol pollutants are believed to lower the surface temperature of the earth. Question What are some polluting gases that mix with air? These gases include carbon monoxide, sulfur dioxide, and nitrogen oxides. Gases are also called gaseous emissions. An emission is any substance that is released or discharged into the air. So in this case, a gas is released as a pollutant. Gaseous emissions are industrial products, such as sulfur dioxide, carbon monoxide, and nitrogen oxides, that are released during various manufacturing operations. Some of these gases may react with other chemicals in the atmosphere to form harsher chemicals that can wreak havoc on the environment. Gaseous emissions are also released from the exhausts of cars and trucks or anytime fossil fuels are burned. What are examples of fossil fuels? Fossil fuels include coal, natural gas, and oil.

Snorkeling, scuba diving

As Velma stepped into the warm marine waters of the Red Sea off the coast of Sharm El Sheikh, Egypt, she marveled at how she could see to the bottom although the water level was over her waist. She didn't even need her snorkeling mask to enjoy watching all the brightly colored fish swimming around. In the distance, however, was her destination--a coral reef, a rock ridge formed by a colony of animals called corals. Velma's parents had warned her to be careful around the coral reef because although it looked sturdy, corals are delicate and take a long time to recover from damage. Velma put on her snorkeling mask and swam above the coral, making sure she didn't touch anything or get too close. Unfortunately, she saw where other tourists had not been as careful. Watch this video to learn the ideal conditions of where coral reefs form. Visitors to the beach often enjoy the sun, the warmth, and the salty water. One of the most important marine animals, corals, actually depend on all three conditions to survive. Corals may be small animals individually, but their exoskeleton fuse together with other corals to form a colony known as a coral reef. Coral reefs grow best in shallow water where sunlight can reach them. For this reason, marine plants attach themselves to corals. Other marine animals eat these plants, which attracts larger marine animals to eat those marine animals. As you can see, a healthy coral reef depends on good environmental conditions and a balanced interaction with other marine organisms. Transcript Question What is the ideal environmental condition for a coral reef? The ideal environmental condition for a coral reef is warm, shallow marine water.

biomass power

Biomass power--like wind, solar, and hydropower--is a source of energy that can be reused. Biomass energy is the energy stored in organic matter because of photosynthesis. Biomass energy sources are also called biofuels. They include wood, aquatic plants, and plant wastes (vegetation) left after harvest. Plants use up much of the sun's energy to make their own food. As the plants die, the energy is trapped in the residue. This is similar to the energy stored in fossil fuels. Fossil fuels are formed from dead plants and animals (organic matter) containing carbon. When biofuels are burned, trapped energy is released and can be converted into heat and electricity. Biomass power is such a widely used source of energy that it accounts for almost 15% of the world's total energy supply and as much as 35% in developing countries--mostly for cooking and heating. Biomass power can be used to generate electricity and fuel some engines. Click the tabs below to learn how biomass power is used to generate heat and electricity. Also, take note of the usability of biomass power by comparing its advantages and disadvantages. How Biomass Power Works Advantages of Biomass Power Disadvantages of Biomass Power Biomass power is a very common way of converting organic matter into energy. Burning things like wood, waste, and other plant matter releases stored chemical energy in the form of heat, which can be used to turn blades in turbines to produce electricity. This image shows a power plant that generates electricity from burning wood chips. This process is very similar to the generation of electricity using fossil fuels, except that plant products are burned instead of oil, gas, or coal. When water is heated, what is produced that actually turns the blades of a turbine? Steam is produced.

deforestation

Currently forests cover about 30% of the world's land mass. However, this percentage is decreasing. An estimated 18 million acres of forest, roughly the size of the entire country of Panama, are lost each year. Recall that human population growth continues to increase. More people require more resources such as shelter and land to grow crops or raise livestock. This results in deforestation. Deforestation is the permanent destruction of forests to make the land available for other uses. I speak for the trees, for the trees have no tongues. - Dr. Seuss, The Lorax You are probably familiar with the classic children's book The Lorax. Long before being "environmentally friendly" was mainstream, Dr. Seuss's Lorax spoke for the trees and warned of the dangers of destroying the environment. Dr. Seuss educated a new generation of young readers not only about the importance of seeing the beauty in the world, but also about their responsibility to protect it. Question What do you think the Lorax meant by the quote above? Someone has to speak out for the forests to protect them from destruction by humans.

Amazon Forest

Deforestation is a particular concern in tropical rainforests because these forests are home to much of the world's biodiversity. The Amazon rainforest located throughout Brazil, Peru, Bolivia, and other parts of South America is the largest in the world. Since 1978 over 289,000 square miles of Amazon rainforest have been destroyed. In the time it takes to watch the video below, an area of Brazil's rainforest larger than 100 football fields will have been destroyed. Watch the video to find our why. At first, deforestation occurred by farmers who cut down trees to produce crops for their families and build structures to live in. But in the later part of the 20th century, that began to change. More deforestation was driven by industrial activities and large-scale agriculture. By the 2000s more than three-quarters of forest clearing in the Amazon was for cattle-ranching. Vast areas of rainforest were destroyed for cattle pasture and soybean farms, dug up for minerals, and bulldozed for towns and urbanization projects. At the same time, the construction of roads opened previously inaccessible parts of the forests. These now open areas were settled by poor farmers, subjected to illegal logging, and land development. This time-lapse shows the deforestation that happened in just 12 years. Scientists fear that an additional 20 percent of the trees will be lost over the next two decades. Unfortunately, deforestation is the result when human population puts higher and higher demands on natural resources.

greenhouse effect

Earth's atmosphere maintains the temperature within a range to support life through a process called the greenhouse effect. Take a look at this detailed diagram. Then read the information in the table to better understand how solar energy is used to heat the planet. Click on each step in the table for its explanation. As you read about this process, pay special attention to the flow of energy. Step 1About 70% of solar energy is absorbed by the atmosphere and Earth's surface, especially the oceans. Step 2The remaining solar energy is reflected into outer space by Earth's atmosphere and surface. Step 3Infrared energy is generated by heated objects. The hotter the object, the more infrared energy is given off. Infrared energy flows from the surface into the atmosphere. Step 4The atmospheric gases, also called greenhouse gases, absorb most of the infrared energy. These gases spread the heat from infrared energy, which warms both the lower atmosphere and Earth's surface. Question How do greenhouse gases help warm up Earth? Greenhouse gases absorb and spread the heat from incoming solar and infrared energy.

alternate energy sources

For many years, it was thought that much of society's energy needs would be met by nuclear energy. Giant nuclear power plants, also called nuclear reactors, were built in several countries, including the U.S. These power plants generate electricity by splitting the atoms of the element uranium. Atoms of uranium are split by being bombarded with neutrons, which are parts of atoms with a neutral charge. This releases a huge amount of energy to generate electricity. No greenhouse gases are released during the process, and sources of uranium are plentiful. This sounds like the perfect source of energy, but even though nuclear reactors are efficient at transforming energy into electricity, accidents can happen. Watch this video to learn about the worst disaster in the history of nuclear power. This explains just one of the reasons we don't have nuclear power plants generating electricity in every city around the world. In 1986, an explosion and fire occurred at one of the reactors at Chernobyl in the former Soviet Union, causing the reactor to crack and leak out radioactive steam. This led to the worst accident in the history of nuclear power. Many deaths and injuries resulted. Over 100,000 people had to be evacuated from their homes. Winds carried radioactive fallout over much of Europe. Some people died years later from cancer associated with radiation exposure. Some people are still afraid of the risk of such accidents, though there have been many improvements to nuclear facilities in the wake of this disaster. Transcript The nuclear power generation process creates wastes that are dangerously radioactive for thousands of years. No permanent, safe method for disposal of nuclear wastes has been developed. Public opposition, high costs, and technical problems have led to a decline in the demand for nuclear power, and many countries have decided to reduce or completely eliminate their nuclear energy programs. Even though nuclear power has not become the "energy of the future," there are some promising alternate energy sources available to us. Question Other than fossil fuels and nuclear energy, what are some other sources of energy? Sun, wind, water, biomass, and geothermal energy are other possible sources. We depend on energy. All the machines and electronic devices you use need an energy source to work. In industrialized nations, the majority of energy used comes from fossil fuels. What are the three types of fossil fuels? They are oil, coal, and natural gas. A nuclear power plant. Fossil fuels, which are nonrenewable energy sources, are being consumed rapidly. Nonrenewable energy sources cannot be used over and over again. Once fossil fuels are burned, they are used up. Also, the use of fossil fuels has negative impacts on the environment, such as global warming and pollution. Since nuclear energy is supplied by uranium, and it can be used up, it is also considered a nonrenewable energy source. Nuclear energy is energy in the nucleus (core) of an atom. Atoms are tiny particles that make up every object in the universe. There is enormous energy in the bonds that hold atoms together. It is usually in a form of heavy metal, such as uranium, that is naturally occurring in most rocks, soil, and even in the ocean. Energy from uranium is called nuclear energy. Power generated from nuclear power plants is similar to that of fossil fuels because they all use heat to turn blades in turbines to generate power. However, remember that nuclear power is not the most widely used source of energy because of its generation of radioactive wastes and the possibility of nuclear disasters. Solar energy, wind energy, and biomass energy derived from vegetation are alternatives to burning fossil fuels. What are some safer alternatives to nonrenewable energy sources? Energy exists freely in nature. Some of the energy exist infinitely and never runs out. These are called renewable energy sources and can be used over and over again. Water, wind, sun, vegetation, and heat within Earth's crust are all available naturally. These renewable energy sources can be used to produce heat and steam to generate electricity. In 2012, 9% of the energy consumed in the U.S. came from renewable sources. This means we heavily depend on nonrenewable sources, such as fossil fuels. In this lesson, you will learn about alternate energy sources that are renewable. Question Why is it important to develop alternatives to fossil fuels?

driving causes for deforestation

Forests are vital habitats to a wide variety of organisms. They help absorb greenhouse gases, produce large amounts of oxygen, and perpetuate the cycling of water. Forests do so much for our planet, yet humans continue to destroy them for other uses. Why are humans driving the destruction of forest ecosystems? Deforestation occurs around the world. Though deforestation has increased rapidly in the last 50 years, it has been practiced throughout history. Currently, countries with significant deforestation include Brazil, Indonesia, Thailand, the Democratic Republic of Congo and other parts of Africa, and parts of Eastern Europe. Remember, the human population continues to explode, so more people bring about more deforestation. Click through these slides to learn about some of the human activities that cause deforestation. Agriculture In the Amazon, forests are cleared for agriculture in Brazil. Agriculture, or farming, is the largest driver of deforestation in which vast areas of natural forest are burned or cleared to raise cattle or grow crops. Usually forests are burned to quickly make the land available for planting. Sometimes fast growing crops, like palms and soybeans, are planted on lands cleared of their forests; these crops make a quick profit for the farmers. Palm oil and soy are used in a wide array of products ranging from toothpaste, chocolate, animal feed, and cosmetics. Why do you think these crops are sometimes called "cash crops"? Cash crops like palm and soy grow quickly and make money fast. Question The largest rainforest in the world, which is located in South America, is decreasing in size due to deforestation. This massive rainforest is located in and around a well known river that winds through parts of South America. What do you think the name of this rainforest is that may soon be lost? It is the Amazon rainforest. Industrial logging involves the use of trees by industries for their wood products. Trees are cut down for their timber, pulp, and wood fiber to create building materials, firewood, and consumer products. A practice called clear cutting is often used to harvest massive numbers of trees. Clear cutting involves the complete removal of a given tract of forest using bulldozers and large powerful saws to cut the trees down. No trees in the area are left standing. What consumer products are made out of trees? Paper, tissue, books, magazines, and packaging are all made from trees. Mining for metals, such as gold, copper, and aluminum, clears large tracts of natural forests. Trees are cleared so that mine workers can more easily access the area to collect valuable metals. Forests are cleared or burned to make roads. Road building through forests chops up the landscape and endangers wildlife habitats. Sometimes these new roads provide access points for loggers, miners, and other business operations that travel into the forest. How do you think road building endangers the wildlife habitat in the forest? Animals that live in the trees will lose their homes. Plants and other species may be destroyed as vehicles and humans invade their habitat. Earth must support the growth of the human population. Forests are cleared so that an increasing number of houses, apartment buildings, factories, and businesses can be built. Lands where forests once stood are turned into towns and cities. What does urbanization mean? Urbanization is the population shift from rural to urban areas. This means more people are moving into urban areas or cities instead of out in the rural or country areas.

Coral reef ecosystems

Fortunately for Velma, she and her family visited coral reefs that had very little damage. The reefs with the least damage are the ones that tourists can only access by boat with a guide. Their guide explained that coral reefs represent an important marine ecosystem, which is an area with interacting organisms within a physical environment. Even though less than one percent of the ocean floor is covered by coral reefs, about 25% of all marine organisms live there! Coral reefs fascinated Velma, not just for their beauty, but also because the animals, the corals themselves, live in a colony in which their exoskeletons (a protective covering on the outside of an organism's body) join together to provide a living space for other organisms. Click through these tabs to learn about the organisms that make up the coral reef ecosystem. Polyps Exoskeleton Zooxanthellae Fish Around a Coral Reef Corals, also known as polyps (shown in blue), are multicellular animals that belong to the phylum Cnidaria. Polyps have very little organ development. Their tentacles capture food and pass it to the mouth. The mouth doubles as an anus, allowing waste products to exit. The pharynx helps pull food into the mouth and push waste out. The septa (plural of septum) are plates that secrete the protective exoskeleton. Polyps live in a genetically identical colony since they reproduce asexually through budding. Budding occurs when the parent polyp reaches a certain size and divides. Polyps can also reproduce sexually when they release either sperm or eggs into the water. The release of sperm and eggs is called spawning. Spawning is the only time corals are able to move around, which is important to start a new coral reef in a new location. Question Besides polyps, what other two populations live in the coral reef ecosystem? The other two populations that live in the coral reef ecosystem are algae and fish. Corals secrete calcium carbonate (CaCO3), which forms the protective exoskeleton, through their septa. The exoskeleton supports and protects the coral's body. Additionally, the fused exoskeletons of a colony of corals form the coral reef. Live corals form a layer on top of dead corals. Corals may grow at a rate of .3 cm to 10 cm a year. Zooxanthellae is a type of marine algae that has a mutualistic relationship (a type of symbiotic relationship where both species benefit) with corals. The corals provide a protective area, the exoskeleton, for the zooxanthellae to grow within. Since coral reefs form in shallow waters, zooxanthellae benefit from the amount of sunlight it receives for photosynthesis. The zooxanthellae provide the corals with nutrients, such as glucose and oxygen, through photosynthesis. From respiration, corals provide zooxanthellae with some of the carbon dioxide it needs. Zooxanthellae also provide corals with beautiful coloring. Without zooxanthellae covering the exoskeleton, the corals would be white. The fish around a coral reef are thin, which allows them to make sharp turns around the reef. These fish are also brightly colored for hiding among the corals, mate recognition, and warning. The herbivorous (plant-eating) fish feed on zooxanthellae, while carnivorous fish feed on other animals. The feeding relationships keep all organism populations balanced so that no one population grows excessively compared with the other populations.

burning fossil fuels

Fossil fuels are created deep underground from the remains of dead plants and animals. It seems that something formed in such a "natural" way should be harmless. Fossil fuels are basically harmless to the environment until we decide to harness their energy. We get so much out of these energy sources but not without a cost to the environment. Many of the environmental problems on Earth today are the result of the use of fossil fuels. Click the tabs below to learn how the extraction and burning of fossil fuels impact the environment. Global Warming Air Pollution Water Pollution Land Pollution Thermal Pollution One of the most significant greenhouse gases emitted when fossil fuels are burned is carbon dioxide. What is a greenhouse gas? A greenhouse gas is a gas that traps heat in the atmosphere. Over the last 150 years, burning fossil fuels has resulted in more than a 25 percent increase in the amount of carbon dioxide in the atmosphere. Since reliable records began in the late 1800s, the global average surface temperature has risen 0.5-1.1 degrees Fahrenheit. Climate scientists predict that if carbon dioxide levels continue to increase, the planet will become warmer in the next century. Sea levels could rise due to the warming of oceans and melting of glaciers, causing flooding in some areas. Altered weather patterns may result in more extreme weather events, such as hurricanes and tornadoes. Also, inland areas could suffer an increase in the frequency of droughts, as shown in this image. Question What are some ways fossil fuel use negatively impacts the environment? Global warming and pollution (air, land, water, and thermal) are two negative impacts. Clean air is essential to life and good health. Several harmful pollutants are produced by the burning of fossil fuels: carbon monoxide, nitrogen oxides, sulfur oxides, and hydrocarbons. Nitrogen oxides and hydrocarbons can combine in the atmosphere to form ozone, which is a major component of smog. Sometimes when an air pollutant such as sulfuric acid combines with water droplets that make up clouds, the water droplets become acidic, forming acid rain. How does acid rain affect the environment? When acid rain falls over an area, it can kill trees and harm animals, fish, and other wildlife. Fossil fuel use also produces particulate matter pollution, including dust, soot, smoke, and other suspended matter, that can irritate the respiratory system of some organisms. Production, transportation, and use of oil can cause water pollution. Oil spills, as shown in this image, leave waterways and their surrounding shores damaged for some time. How do oil spills result in a loss of biodiversity? Biodiversity is the variety of life on Earth. Oil spills often result in the loss of plant and animal life. Coal mining also contributes to water pollution. Coal contains pyrite, a sulfur compound. As water washes through mines, pyrite forms an acid that is then washed into nearby rivers and streams. This can produce effects similar to that of acid rain. Coal mining affects the area that is being mined. Characteristically, the land closest to the coal is acidic. After the mining is completed, the land will remain barren because of the acidic land. This means that very few plants will grow there. This image shows a coal mine in Portugal that was abandoned a decade ago. What do you notice about the number of plants in the area? There are very few plants growing in the area because the land has been polluted. Materials other than coal, such as sediment and rocks containing other chemicals, are also brought to the surface in the coal mining process. These materials are sometimes left as solid wastes. As the coal itself is washed, more waste material is left behind. Thermal pollution is the sudden increase or decrease in temperature of a natural body of water that can cause harm to the living things inhabiting that body of water. During the process of generating electricity, burning fossil fuels produces heat energy. Much of the heat generated does not directly produce electricity but is lost during the process. Excess heat is released into bodies of water that are used as coolants. Heated water, once returned to rivers or lakes, can upset the aquatic ecosystem. Why do you think increased water temperature can upset an aquatic ecosystem? Small aquatic animals, as well as plants, can be harmed or killed by a change in temperature. Also, warm water holds relatively less oxygen than cold water. The decrease in oxygen levels can also kill organisms living in the water.

geothermal power

Geothermal power is also an alternate, renewable energy source. Instead of using the sun, wind, or biomass as an energy source, though, geothermal power takes advantage of underground heat. Geothermal power plants, like the one shown here, use this heat to produce hot water or steam for direct use or to power turbines for electrical generation. Deep in the Earth's crust, there is molten rock--that is, rocks that have melted into liquid form as a result of extreme heat. This kind of rock can be found about 1,800 miles below the surface. But closer to the surface, the rocks layers are hot enough to keep water and air spaces there at a temperature of about 50-60 degrees F. Geothermal technology takes advantage of these hot temperatures to generate power. Click the tabs below that outline how geothermal power works, as well as its advantages and disadvantages. How Geothermal Power Works Advantages of Geothermal Power Disadvantages of Geothermal Power In places with hotter temperatures close to the surface, deep wells can be drilled and cold water pumped down. The water runs through fractures in the rocks and is heated up. It then returns to the surface as hot water and steam where its energy can be used to drive turbines and electricity generators. In other places, a geothermal heat pump system consisting of pipes and pumps buried in the ground can be used to heat homes, such as in this image. Cold water is shown in blue, and hot water is red. Cold water is sent down to the hotter area below ground where it is heated, and then it is pumped back into the house. This hot water is used to feed an indoor air delivery system during the cold season. In other words, the hot temperatures deep underground are used to heat a house! Geothermal power has a minimal environmental impact with only the ground where the pumps are installed being disturbed. This method of electricity generation is efficient, and power plants using this form of power release little to no air pollutants or greenhouse gases. Homeowners using this kind of power find that after the initial cost of digging and installing the heat pumps, the costs to heat a house are low. This image shows a geothermal power station in Iceland. About 81 percent of the total primary energy supply in Iceland is derived from renewable energy sources. Because this method of generating energy for use is fairly new, there are not many geothermal power plants. The start-up cost to install a home heat pump or build a geothermal power plant is very expensive. Also, underground temperatures vary throughout different landscapes and different parts of the world. Certain areas may not be ideal locations to install geothermal systems.

changing climate

Global warming is a major impact of the burning of fossil fuels. Scientists have warned that the world's climate has changed a lot and has affected many living and nonliving things. Many places that were warmer are now getting colder, and many colder regions are getting much colder or even warmer. Global warming refers specifically to any change in the global average surface temperature. How do scientists know this is happening? One study published in 2013 provides one piece of evidence that supports global warming. Lusher plant growth typically associated with the United States is now becoming more common in much colder Canada. Where is Canada located compared to the United States? Canada is north of the U.S. Watch this video to find out how this study provides evidence for global warming. Is Canada the new America? Plant growth at Earth's northern latitudes increasingly resembles lusher latitudes to the south. For the last 30 years, satellite images of plant coverage were viewed and studied. NASA scientists examined the relationship between changes in surface temperature and vegetation growth. They found that higher northern latitudes such as Canada are getting warmer. They believe this is due to decreases in Arctic sea ice and the duration of snow cover. On this map, red means that the temperatures are warmer than the averages. The majority of North America is warmer than average during this period. This means the growing season is getting longer and plants are growing more. The results can be seen on satellite images showing greener, thicker plant coverage. It looks like Canada is turning into a more tropical paradise. Transcript Question Global warming is happening. What evidence exists to support this statement? Satellite images and a scientific study show that plant growth in Canada is now resembling that of the U.S. Warmer temperatures result in a longer growing season, producing more lush vegetation.

disappearing wetlands

Global water shortage means that there is not enough water for all living things on our planet. When people do not have enough water, this can lead to an increase in diseases and hunger. It can also lead to damaged ecosystems which can be devastating. A specific example of an ecosystem that can be destroyed by water scarcity is a wetland. Wetlands, pictured in the images here, are the link between land and water, and are some of the most productive ecosystems in the world. Wetlands, also called marshes or swamps, are places where there is shallow water or very soggy soil at least part of the time. If there is less water due to climate change or the water is used by humans for other purposes, wetlands dry up and disappear. View the video that explains the importance of wetlands and why they are disappearing. As you view the video, think about how water shortage affects this ecosystem. Some of the most productive habitats on the planet, wetlands support high concentrations of animals, including mammals, birds, fish and invertebrates. Wetlands also support the cultivation of rice, a staple in the diet of half the world's population. They provide a range of ecosystem services that benefit humans. Wetlands act like sponges by holding flood waters and keeping rivers at normal levels. Wetlands filter and purify water as it flows through the wetland plants. Plants found in wetlands help control water erosion. About half of the world's wetlands have been destroyed since 1900, due to water shortage. The United States has lost over half of the wetlands in the lower 48 states, and the losses continue at an estimate of over 60,000 acres per year. As more people populate the earth, they require more land for development and create more pollution. People drained, dredged, dammed and channeled wetlands, eliminated or converted them into dry land or filled them for lakes and water retention areas. They changed wetlands into cropland, pasture, and subdivisions, causing many of our wetlands to disappear. If the wetlands continue to disappear everyone will be affected in one way or another. Transcript Check your understanding of the effects of water shortage on wetland ecosystems. Jot down an answer to each of these questions--or say the answer to yourself--before clicking the question to see if your answer was correct. If wetlands continue to disappear, why will some environments be more prone to flooding?Wetlands act like sponges by holding flood waters and keeping rivers at normal levels.How have humans directly caused the destruction of wetlands?They drained and dredged wetlands or converted them to dry land for other uses.How can the destruction of a wetland result in loss of biodiversity?High concentrations of animal species live in wetlands. If their habitat is destroyed they can die out.

Zombie Apocalypse

In the 1981 horror movie, Night of the Zombies, the world is overrun by zombies. In New Guinea, a chemical plant leaks a gas that causes humans to turn into flesh-eating zombies. A team of four survivors try to evade these creatures and find themselves in the middle of a full-fledged zombie apocalypse! They end up at the same chemical plant where the whole thing started. The plant is overrun by zombies, too. The survivors are killed one by one, but not before they discover that the gas was created and released intentionally by a team of scientists. It was designed to make the local people of New Guinea feed on each other, and thus, solve the crisis of overpopulation. Makes for great movie, right? Yes, but there was an underlying theme. Bruno Mattei, who wrote and directed the film, touched on one of the major problems facing this world today: overpopulation. Overpopulation means that there are too many of one kind of animal in a given area for the area's natural resources to be able to sustain. Question If humans are the "animal" in question, how would you define overpopulation? Overpopulation is a situation in which the number of humans exceeds the number that Earth can sustain.

global warming

Karl was one of the newest members of the Environmental Club at his high school. One of its goals was to educate the school community about global warming, which is the gradual rise in the average temperature of Earth over time. The first thing Karl had to learn about was the natural way Earth retains heat from the sun. The atmosphere is a mixture of gases that envelope a planet. The greenhouse effect is a process in which the atmosphere absorbs, traps, and distributes heat from the sun. Without these greenhouse gases, no life could exist on Earth because the temperature would be too cold. Watch the greenhouse effect video below that Karl's Environmental Club shows all new members. Do you remember the story of Goldilocks and the Three Bears? In one part of that story, Goldie Locks tried all three soups. One was too hot, another was too cold, but the third one was just the right temperature; so she ate it all. In a way, life on Earth is just like Goldilocks' choice of soups. One of the reasons life exists on Earth is due to the temperature being just right to support life. The Sun radiates heat toward Earth. Some of this heat bounces off Earth, but most is absorbed by gases in the atmosphere or Earth's surface. When solar heat is absorbed and trapped by atmospheric gases, the process is called the greenhouse effect. The greenhouse effect helps to maintain an average temperature for living things. Human activity has had unintended consequences on the greenhouse effect. Emissions of carbon dioxide by power stations and other processes increase the amount of this gas in the atmosphere, leading to global warming. Transcript Question What is the greenhouse effect? The greenhouse effect is a process in which atmospheric gases absorb, trap, and distribute solar heat.

wind power

Like solar energy, wind power is also a renewable source of energy. Do you think we will ever run out wind? Probably not. Even though the wind is not blowing all the time in all areas, it can be used as an alternate energy source. Wind is caused by currents in Earth's atmosphere that are driven by heat energy from the sun. This means that as long as the sun shines, there will be wind. Wind power is energy generated by air movements. Wind energy is used to generate electricity or to do mechanical work, such as pumping water for agriculture. Notice that in this image a windmill is used to pump water from a nearby dam into a collection tank for livestock. Click the tabs below to learn how wind power is converted into energy for use, as well as the pros and cons of using wind as an energy source. How Wind Power Works Advantages of Wind Power Disadvantages of Wind Power In open areas with moderate to strong winds, energy can be generated using windmills, which are also called wind turbines. Clusters of wind turbines, like the ones in this image, are called wind farms. Moving air (wind) has huge amounts of kinetic energy, which is the energy of motion. This kinetic energy is converted into electrical energy in the turbine of a windmill. The wind turns the blades in the turbine, which connects to a generator, and makes electricity. Why do you think wind turbines are sometimes located on high hills? Wind turbines are usually situated on high hills, like the ones shown here, and mountain ridges to take advantage of the prevailing winds (winds that blow predominantly from a single general direction). A major advantage of wind power is that there are no pollutants or greenhouse gases released during the energy conversion process. Solar energy is a very clean way to create electricity. Once the windmills are set up, they are fairly affordable to maintain and generate electricity. Since the energy output is proportional to wind speed, wind power is not a feasible option for all areas. If there is little or no wind in a certain geographical area, windmills would not be able to generate electricity. Also, to generate large amounts of electricity, a great deal of land, such as seen here, is needed for numerous windmills.

consequences of coral reef damage

Lower Biodiversity Less Income Increased Erosion Increased Atmospheric CO2 The biodiversity of a coral reef in Riviera Mayan, Mexico. Since 25% of marine life lives in a coral reef, damage to this ecosystem leads to a lower biodiversity, which is the number of different species living in an area. Some species will become extinct. Often times, medical science looks to nature for possible solutions to today's challenges. Without those species, cures for diseases may go undiscovered. Question How does coral reef damage affect life globally? Coral reef damage decreases the chance to find medical cures, lowers income, erodes land, and increases the global average temperature. In addition to lowering the biodiversity, some moneymaking industries, such as fishing and tourism, around the world are affected as well. Fishermen have fewer marine organisms to capture and sell. Tourists visit in fewer numbers and spend less money in areas where damage to the natural beauty has occurred. When coral reefs are damaged, there is more land erosion. Since reefs develop in the shallow waters off the coast, their presence helps slow down the speed of incoming ocean waves. Slower waves have less energy to erode the land. Damaged coral reefs do not protect the land from erosion as well as healthy reefs do. As the ocean absorbs more CO2, its acidity increases, which weakens and eventually kills corals. Zooxanthellae have fewer corals to attach to, which lowers their presence as well. With fewer plants in the ocean, less CO2 is removed from the atmosphere. Therefore, more atmospheric CO2 is absorbed and increases the global average temperature.

Effects of water pollution

Note that water pollution is very harmful to humans, animals, and water life. The effects can be catastrophic, depending on the kind of chemicals, concentrations of the pollutants, and where the pollution occurs. The effects of water pollution are varied and depend on what pollutants are dumped and in which locations. Many water bodies near urban areas (cities and towns) are highly polluted. This is the result of both garbage dumped by individuals and dangerous chemicals legally or illegally dumped by manufacturing industries, health centers, schools, and market places. Any of the different types of pollution being discharged from various sources can affect the environment in a negative way. Click the tabs below to see a summary of the effects of water pollution. In some cases, any one type of pollution can result in all of these effects. Death of Aquatic Animals Disruption of Food Chains Diseases Destruction of Ecosystems Dead fish caused by water pollution. Aquatic animals are animals that live in the water. The main problem caused by water pollution is that it kills life that depends on these water bodies as their habitat. Dead fish, crabs, birds, dolphins, and many other animals often wind up on beaches, killed by pollutants in their environment. What is a habitat? A habitat is a place where an organism lives. Water pollution disrupts natural food chains, like the one illustrated here. Remember that a food chain is when one animal eats an organism, then another animal eats that animal, and so on. Some chemical pollutants, such as lead and mercury, are eaten by tiny animals. Later, these animals are consumed by fish and shellfish, and the food chain continues to be disrupted at higher levels. This means that the pollutant is being passed through the food chain as one organism eats another. All organisms in the food chain are affected. At any level, organisms may become ill or die due to the pollutant. If organisms at one level in the chain die, that leaves no food for other animals higher up in the chain. Hence, the food chain is disrupted. Think about the top of the food chain. What eats fish that may be contaminated with pollutants? Humans! In some cases humans can become ill after eating fish that contain high levels of certain chemicals, like mercury or lead. Sometimes humans are affected by pollutants in the water. People can get diseases, such as hepatitis, by eating seafood that has been poisoned. The virus that causes hepatitis A can be transmitted to humans if they eat undercooked shellfish from contaminated waters. The liver can be damaged by hepatitis A after eating these contaminated foods. In many poor nations, there are outbreaks of cholera and other diseases as a result of drinking water from contaminated streams. Cholera is a disease caused by bacteria that results in severe diarrhea, and infected people can die from dehydration. Ecosystems include the interaction of living things in a specific area that depend on each other for life. Aquatic ecosystems can be severely changed or destroyed by water pollution. Many areas are now being affected by careless human pollution. A loss of biodiversity is a major issue. Some species may be lost, or become extinct, due to water pollution. What is biodiversity? It is the variety of species in a particular area.

causes of water shortage

Our supply of fresh water comes from surface water and aquifers. This fresh water is continuously replenished by the hydrologic cycle. Humans use fresh water water for drinking, washing, waste disposal, irrigation of crops, and the manufacture of many products. So now let's focus on why we are facing a global water shortage. In the United States, far more water is drawn from aquifers that can be replaced by the hydrologic cycle each day. In addition, the quality of water supplies is being reduced. Salt from icy highways, sediment from erosion, and farm and lawn chemicals contaminate water supplies. Many industries release toxic chemical wastes into rivers and streams. A combination of human activities have resulted in a global water shortage. View this slideshow to learn about the important causes of water shortage. Human Population Explosion In the last few decades, the total number of people on earth has doubled and continues to grow. More people means more fresh water is used. Why does the human population continue to increase? The development of immunizations and more effective medicines fight off life-threatening diseases. Better, more plentiful food is grown through agriculture. Improved sanitation provides for a cleaner, healthier water supply. These advancements in medicine, agriculture, and sanitation allow humans to live longer, healthier lives. Because the human populaiton has increased, this means that the use of fresh water for drinking, cleaning, cooking and sewage has greatly increased also. Many humans are a lot more careless in recent time, and we waste more water than ever before. This has placed a lot of pressure on the amount of water that we have available to us. Question Think about the five causes of water shortage you have just learned. How does human population explosion affect the other four? The causes of water shortage are the result of human activities. As human population increases, so does pollution, urbanization, deforestation, and the release of greenhouse gases, resulting in climate change. Cities, such as Toronto, Canada pictured here, are growing and expanding more than ever before. Urbanization is a population shift from more rural areas into urban areas. Cities also tend to hold more people than towns and villages. How do you think urbanization leads to the use of more water? When people move from rural areas into urban areas, there is an increased need to take care of sewage, cleaning, construction and manufacturing, all of which involve the use of water. Water, air, and land pollution together contribute to the reduction of water quality. Water pollution comes from many sources of pollutants that wash away from farms, untreated human wastewater, and industrial waste. What are some pollutants that may wash away from farms and end up in our water sources? fertilizers, pesticides, herbicides Even groundwater is not safe from pollution, as many pollutants can leach into underground aquifers. Sewage, oil discharges from industries, waste dumping into water bodies (as shown in this image), dirty water from sanitation work in hospitals, hotels, oil companies, mining, schools and restaurants all end up polluting our waters. Trees play a major role in the hydrologic cycle by returning water vapor to the atmosphere through evaporation. They also enrich the soils and prevent erosion. This means the destruction of forests by fire, logging and farming has exposed soil moisture and water bodies to the sun's intense heat, leaving them dried out. The small pond in this image was once shaded by a forest of trees. What may happen to the pond after the trees were destroyed by deforestation? The pond may dry out now that it has no shade. As humans continue to pump more carbon dioxide and other greenhouse gases into the atmosphere, patterns of weather and water will change around the world. Recall that greenhouse gases are released when oil, coal, and gas are burned. How do greenhouse gases create global warming? They trap heat in the atmosphere, causing an overall increase in temperature. Droughts will become more common in some places, floods in others. Glaciers, like the one in this image, and snow banks will disappear in some areas, affecting the fresh water supplies to those downstream communities. These changes will combine to make less water available for agriculture, energy generation, cities and ecosystems around the world.

solutions to overpopulation

Overpopulation can lead to environmental destruction, as well as a lack of resources needed to survive. In any case, the human population must eventually stop growing. But what can we do about it? What can be done to control overpopulation? Click the tabs below to learn how overpopulation is being controlled. Government Policies Accessibility to Sexual Healthcare Protection and Research Education and Empowerment Many believe the answer to overpopulation is in government policies that will ensure current and future human needs are met. These policies focus on global issues like poverty, food production, and environmental concerns. Also, many believe that birth regulations may be necessary for more countries. Birth regulations are laws limiting the number of children parents are allowed to have. Do you know of a country that has birth regulations? China imposed a law that couples are limited to one child. Violators of the law must pay stiff fines or face punishment such as jail time. There are other solutions constantly being explored, and there is not one simple answer. Rather, all of these control methods are working together to stop the overpopulation crisis. Unlike other organisms, we can decide whether our population growth will stop increasing through social changes. These changes may be imposed by individual choice or government intervention. For better or worse, we have the unique responsibility to decide the fate of our species and the rest of the planet. Question What are some ways that overpopulation is being controlled? Government policies, accessibility to sexual healthcare, environmental protection, and education are all methods to help control overpopulation. There are many organizations dedicated to helping women and youth have access to sexual and reproductive healthcare. Over 150 million couples do not have access to contraception (birth control) worldwide, so some suggest that an increase in reproductive services would be vital to the cause. Raising awareness among people regarding family planning and letting them know about the serious effects of overpopulation can help curb population growth. Some organizations are looking for long-term solutions that will help repair damage that has already been done. A population can only grow as much as its resources, so various initiatives are aimed at preserving the environment which is damaged by overpopulation. For instance, if we use renewable energy sources for electricity generation instead of burning fossil fuels, we can reduce global warming and help protect the environment. What are some renewable energy sources? Wind, solar, geothermal and hydropower are renewable energy sources. Many believe overpopulation is a result of ignorance. So to curb it, some suggest programs that help spread awareness about minimizing population stresses. For example, right now you are educating yourself about the issue of overpopulation. That is important! If you are educated, this empowers you to make wise decisions.

solar power

Renewable energy sources can be used over and over again. In other words, the supply is unlimited. Think about sunlight: Energy from the sun can be used to generate heat and electricity. Solar power is energy from the sun. Solar energy has been considered a serious source of energy for many years. Vast amounts of energy is made freely available if harnessed by modern technology. Click the tabs below to learn how heat from the sun is converted into energy for use. You should also take note of the usability of solar power by studying its advantages and disadvantages. How Solar Power Works Advantages of Solar Power Disadvantages of Solar Power The sun's energy reaches Earth continuously. This energy can be captured and converted into electrical energy by solar cells. These specialized manmade cells are also called photovoltaic cells. When light strikes a photovoltaic cell, electrons are released, producing an electric current. You may have seen small solar cells on calculators or watches. Larger arrays of solar cells are used to power road signs. Solar panels are different than solar cells. Solar panels, like the ones shown here, do not generate electricity directly. Instead, they heat up water. A pump pushes cold water from a storage tank through pipes in the solar panel. The water is then heated by heat energy from the sun and returned to the tank. Solar panels are often located on the roofs of buildings where they can receive the most sunlight. In some homes and industries, many solar panels are used to heat water into steam, which is then used to turn turbines to produce electricity. How does the use of a turbine generate electricity? Steam is used to spin a fan-like turbine very fast by pushing against its metal blades. The blades turn a generator containing wires and magnets that create a magnetic field. This magnetic field produces electricity. The sun's energy is the most abundant energy source available, so it is a highly renewable resource. Also, energy generated by solar power does not pollute the environment. No greenhouse gases or pollutants are released when heat or electricity is produced. As of now, the installation of solar panels is very expensive. However, as solar technology advances, we may see more widespread use of solar power in the future. Another disadvantage is that solar panels require a very large amount of physical space to capture the most energy from the sun. Look at this image. Numerous solar panels are used to generate electricity by a solar power plant. In many homes and industries, this physical space is not available. Does solar power work in cloudy or rainy weather? No, solar power requires sunlight, so supplemental energy may be required in low sunlight areas.

cancer pollution

Take a look at this image. Does this look like water you might want to drink or swim in? Probably not. The image shows a devastating example of water pollution. In 2010, the Deepwater Horizon oil rig belonging to the large oil company BP blew up in the Gulf of Mexico off the coast of Louisiana. The explosion killed 11 people and unleashed one of the worst environmental disasters in U.S. history. Watch this video discussing some of the effects of this explosion. Although this case is extreme, this should give you a good idea of the possible effects of water pollution. Oil rigs are used to drill for oil beneath the ocean bottom. This oil provides us with gasoline to fuel our cars, boats, and planes. When the Deep Horizon oil rig accidentally exploded, more than 200 million gallons of oil spilled into the Gulf of Mexico. The spill oiled more than 1,000 miles of shoreline along the coasts of Louisiana, Mississippi, Alabama, and Florida. More than 82,000 birds, about 6,000 sea turtles, nearly 26,000 marine mammals, including dolphins, and an unknown, massive number of fish and invertebrates have been killed or harmed by the spill and its aftermath. Scientists say it could be years before the full extent of the spill's damage to the Gulf region's complex and sensitive ecosystems will be known. Transcript What is water pollution? It is not limited to oil spilled into an ocean. Water pollution occurs when pollutants are discharged or released into bodies of water. Pollutants are substances released into the environment that can harm living things. Any change in the properties of water that have a negative impact on ecosystems is considered water pollution. Remember that an ecosystem is a biological community of interacting organisms and their physical environment. Water pollution affects aquatic, or water-based, ecosystems. Question Other than oil, what are some pollutants that may be discharged into bodies of water? Chemicals, nutrient wastes, solid wastes, and garbage can also be water pollutants.

enhanced greenhouse effect

The greenhouse effect is caused by gases called greenhouse gases. These gases come from both natural processes, like volcanic activity and decomposition, as well as human activities, such as deforestation and combustion of fossil fuels. The greenhouse effect is a natural warming process. On the other hand, the enhanced greenhouse effect is the increase of greenhouse gases in the atmosphere due to human activity. Scientists explain that the enhanced greenhouse effect is the cause of global warming, which is the gradual rise in the average temperature of Earth over time. Click through the tabs to learn about the consequences of the enhanced greenhouse effect. As you read, pay attention to how the increase in global temperature affects weather patterns, human health, wildlife, glaciers, and the sea level. Weather Patterns Human Health Wildlife Glaciers and Sea Level Review A rainstorm at sea. Warmer ocean water increases the energy of tropical storms, such as hurricanes. Stronger hurricanes leads to more erosion (removal of soil) and flooding. Warmer temperature increases evaporation, producing drought (lack of water) in some areas. Along with drought, the probability of wildfires increases. Since warmer temperature increases evaporation, some areas receive more rainfall, which causes more flooding. With more heat waves (many days of hot temperature), more people will die from heat-related deaths. Higher levels of CO2, which plants use in photosynthesis, will increase the growth of plants that cause allergies and can trigger asthma attacks in which people have trouble breathing due to a narrowing of breathing tubes. Since warm air increases the formation of ozone, the increase in ground level ozone causes more breathing problems. Increasing temperature allows disease-carrying insects, such as mosquitoes, to spread to warmer areas. Heavy rainfall can wash pathogens (disease-causing organisms) into drinking water. Increased temperature can increase food-related diseases since food spoils faster at higher temperatures. Some plants and animals that cannot survive in cold weather are gaining more geographic territory toward the North and South Poles with the warmer weather. This causes more competition for natural resources, such as food, and due to an increase in competition, some organisms may become extinct. Polar bears are swimming longer distances and drowning because of the melting of ice floes, which are large packs of floating ice. The ocean becomes more acidic as it absorbs more CO2 because carbonic acid is formed in the presence of water. The increased acidity causes shelled animals, such as coral reefs, to have weaker protective shells. Increased temperature causes the melting of ice caps on mountains and glaciers, which are slow-moving masses of ice. More flooding and an increase in the sea level occurs due to melting ice caps and glaciers. The country of Greenland contains 10% of the world's ice mass. If it completely melts, the sea level may rise 21 feet.

Reaching Carrying Capacity

The human population continues to increase dramatically. There are currently over 6 billion people on Earth. Due to advancements in medical care, sanitation, and agriculture, this growth does not appear to be slowing down. Advancements in technology have caused this population explosion and may contribute to possible overpopulation. If the birth rate continues to exceed the death rate, more people will inhabit the planet. If this growth proceeds unchecked, the human population will eventually reach a point at which the environment cannot support any greater size. Resources, such as food, water, and land, will run out, and human population growth will stop increasing. Our population will reach its carrying capacity. What does carrying capacity mean? The size of a population that can be supported by the environment is called the carrying capacity of the environment. So when does an exploding human population become overpopulation? Have we reached our carrying capacity? It seems that we have not quite reached it yet. If we had, then we would start to see human population growth level off or decrease. Our population would naturally reduce in numbers through famine and lack of essential resources, such as fresh water and shelter, if we exceeded our carrying capacity. Famine occurs when food runs out and people starve. Overpopulation is regarded by many as a critical issue concerning the growth and future size of Earth's population. If one day this planet were to become overpopulated, it would mean we had ran out of resources, such as food, water, and space, and we were unable to sustain ourselves. Then the population would decline.

human population

The number of people in the world is referred to as the human population. This population has been growing for centuries. Many of the most serious environmental problems today are related to the tremendous increase in the human population. Human population growth cannot continue to increase at current rates without devastating consequences to the biosphere. Watch this video to determine how many people are residing on Earth today. If human population growth continues to expand at current levels, what is in store for the world's future? In 1850, the population of the Earth was estimated to be about 1 billion. Within 80 years by 1930, the population had doubled, reaching 2 billion. By the mid-1970s it had doubled again, reaching 4 billion. According to the United Nations, the world population hit 7 billion in October of 2103. At this rate, it only takes three years for the world population to increase by the equivalent of another United States. That means that 2.5 billion people will be added to the current population in the next 35 years. That's nearly 260,000 people every day or 180 people each minute. The more the merrier, right? Not in this case. More people means more demand for natural resources like food and water. If you think about what humans have done to the environment so far, think about what more and more humans will do to the environment in the future. Transcript Question How does human population growth negatively affect the environment? Humans can deplete more natural resources, such as food and water, and may increase pollution and destroy habitats.

cooked fossils

The three types of fossil fuels--oil, coal, and natural gas--are used as primary energy sources. They are burned in power plants to give off extreme heat. This heat changes water to steam to generate electricity from spinning a turbine very fast. In addition to using fossil fuels to generate electricity, they are also used to heat homes and cook food, among other things. These valuable energy sources come from deep below the ground. But how did fossil fuels get there to begin with? Click through the slides below to learn how fossil fuels are formed from the remains of dead organisms. Carbon-Rich Organisms Die Fossil fuels are mainly made up of carbon because they are formed from prehistoric plants and animals like these microscopic water fleas in the image. These prehistoric living things were primarily microscopic organisms, such as phytoplankton (plants) and zooplankton (animals); however, coal is formed from larger plants like trees and ferns. Notice the second layer from the bottom in the image above. Remember that all livings things contain the element carbon. Substances that contain carbon are considered organic matter. This means that fossil fuels are composed of organic matter. Recall that carbon atoms easily form bonds with other atoms, including other carbon atoms. When carbon atoms form bonds with other atoms, what is stored in these chemical bonds? These chemical bonds store large amounts of energy, so this is why fossil fuels make good sources of energy. Fossil fuels are full of organic matter from dead organisms that contain carbon bonds that store energy. It is believed that fossil fuels were formed over 300 million years ago when Earth's landscape was much different. It had swampy forests, very shallow seas, and a warmer climate. This time is referred to as the Carboniferous period. Question The Carboniferous period lasted from about 359.2 to 299 million years ago. Why do you think this time period is referred to as carboniferous? This time period was named in reference to the rich deposits of oil, natural gas, and coal that were formed during that time. Oil and gas formation begins with the accumulation of organic matter on the sea floor. The tiny organisms (plankton) that form oil and natural gas lived in marine environments within oceans and seas. These organisms died and fell to the bottom of the sea, as shown in this image. Coal formation begins with the dead remains of organisms raining down on the floor of freshwater swamps, rivers, or lakes. What type of dead organisms fell to the bottom of lakes to form coal? Coal is formed from plants (trees, ferns, and other plants). The remains of dead organisms were then covered by sediments, such as mud. As the mud was buried by more sediment and temperature and pressure increased, it started to change into rock. Notice the layer of sediments in the image at the top of the screen. The dead plants and animals began to decompose, or break down into simpler forms of matter, under the numerous layers of sediment. The decomposing remains began to "cook" as the temperature and pressure increased. During coal formation, the accumulated plant debris initially formed a material known as peat during the "cooking" process as it was covered with more and more sediment. This decomposition process occurs in rather unusual settings where the sea or swamp floor is stagnant such that there is no oxygen present to break the organic remains down completely. What does stagnant mean? It means "still." If the conditions are just right, oil, coal, and natural gas form. Microscopic plankton decomposed and converted into oil. Some of this oil continued to "cook" and eventually converted into natural gas. That is why natural gas is usually found near oil deposits underground. During coal formation, plant remains decomposed and converted into peat, which was then converted into coal. Earth movements and rock shifts create spaces that are forced to collect the oil, gas, and coal. With the help of technology, engineers are able to drill into the sea bed or below land to tap the stored energy.

air pollution control

There is no doubt that humans cause air pollution. Most of this air pollution we cause results from the burning of fossil fuels, such as coal, oil, natural gas, and gasoline, to produce electricity and power vehicles. Since we are the cause, what can we do to control the amount of air pollution released into the environment? Efforts are being made in many places to control air pollution. In some countries where much of the air pollution is caused by exhaust from automobiles, the induction of emission controls have reduced pollution. This means that automobile engines are now built to ensure that fewer pollutants are released from the exhaust. Also, waste gases from industrial processes are being treated to remove the most serious pollutants before the gases are released into the atmosphere. Pollution control is the process of reducing or eliminating the release of pollutants into the environment. It is regulated by various environmental agencies that establish limits for the discharge of pollutants into the air. These imposed regulations are called clean air acts, and they are designed to bring awareness to and reduce the amount of air pollution. For example, the Air Pollution Control Act of 1955 was the first United States clean air act enacted to address the environmental problem of air pollution. A wide variety of devices and systems have been developed to control air pollution. Since then, amendments have been made to give the federal government more power to enforce the regulation of industry emissions. In the U.S., new and stricter emission standards were created for the automobile industry in 1995. Methods of air pollution control can be divided into the two categories you learned about--the control of particulate matter and the control of gaseous emissions. Click through these tabs to learn some specific ways air pollution is being controlled. Particulate Matter Control Gaseous Emissions Control Methods for particulate control tend to operate on a common principle. The solid particles are separated from the smoke or gases. Then the waste gases or smoke is passed through a series of filters or a settling chamber. Filters remove many of the solid particles from the smoke. A settling chamber is a long, wide pipe through which gases from a manufacturing process are allowed to flow. As these gases slow down in the pipe, the solid particles settle out at the bottom. They can then be removed from the bottom of the pipe. A cyclone dust collector like the one shown here is another device for removing solids from gases released from a smokestack. The gases are fed into a rotating cylindrical container. As the cylinder spins, centrifugal forces (the forces that move things away from the center of rotation) send solid particles in the gas outward against the walls of the container. The solids collect there briefly and then fall to the bottom of the container. Gases from which the solids have been removed then escape from the top of the container. Why do you think this dust collector is referred to as a cyclone collector? The shape of the cylinder resembles a cyclone, and the gases that rotate through it circulate in a powerful circular motion like a cyclone. Question What are two ways that pollution is being controlled? Since 1995 automobiles have been built to release less pollutants in the air. Also, clean air acts have been established that reduce the amount of pollutants released from industrial processes. Many different methods are available for removing unwanted gases, most of which are acidic. Scrubbers, like the one shown here, are smokestack devices that contain a chemical such as sodium hydroxide. When gases escape from a factory and pass through a scrubber, they react with the chemical and are neutralized. This means the acidic chemical is made more neutral by an increase in pH. From time to time, the scrubbers are removed from the smokestack, cleaned, and replaced. Since the unwanted gases are acidic, the chemicals used to neutralize the acids must be what type of chemical? Chemicals, such as sodium hydroxide, are bases or alkalines. Recall that acids have a pH less than 7 and bases have a pH higher than 7. If an acid is mixed with a base, it is neutralized. Another method for controlling gaseous emissions is by absorption. Activated charcoal is charcoal that has been ground into a very fine powder. In this form, charcoal has the ability to absorb, or adhere to, other chemicals. When unwanted gases flow over activated charcoal on the inside of a smokestack, they are adsorbed by the charcoal. As with scrubbers, the charcoal is removed from time to time, and a new lining of charcoal is installed in the smokestack.

generating electricity

Think about all the things you do that require electricity. You turn on the lights at night, watch TV, and charge you cell phone all using electricity. Where does this power come from? All three types of fossil fuels--oil, coal, and natural gas--can be used to generate electricity. Which fossil fuel is used to generate over 50% of the electricity in the United States? Coal generates over 50% of U.S. electricity. A power plants generates electricity fueled by coal. The process of generating electricity is very similar when using any of three fossil fuels. The fuel is burned in power plants, also called power stations. The heat energy given off from burning the fossil fuel is used to heat water to produce steam. This steam is then used to turn a turbine to create electricity. A turbine, like the one shown here, is a wheel-like apparatus with blades that turn like those of a fan. This table highlights the basic steps in the process of generating electricity. Fossil Fuel BurnedOil, coal, or natural gas is burned in turbines in power stations to produce extreme heat, which is used to create high-pressure steam. Steam Spins TurbineSteam is used to spin a turbine very fast by pushing against metal blades. Electricity ProducedThe blades turn a generator containing wires and magnets. The resulting magnetic field produces electricity. Electricity Transformed and RegulatedThe electricity flows to a transformer that changes it to very high voltage electricity. The transformer also regulates the amount of electricity that is produced and supplied. Electricity DeliveredElectricity is sent to homes, factories, and other places in the world. Question Look at the image of the power plant at the top of the screen again. Coal is used here to create electricity, but what do you notice about this process that may be harmful to the environment? A large amount of smoke is coming out of the smokestacks. This is a source of air pollution.

water shortage

This is a lyric in a popular reggae song by the legendary artist, Bob Marley. Even though he was singing about being loved, this simple quote can be used to sum up the global water shortage on Earth. What do you think this quote means when referring to our water supply on Earth? We are not going to be concerned about running out of water until it is gone. Water is required for life. Plants, animals and humans all depend on this invaluable natural resource to carry out their life processes. Besides this, water is used in moving waste, cleaning and sanitation, manufacturing, construction and farming. Almost every human activity you can think of involves some use of water. For you, a supply of water has probably never been a big deal in your life. If you live in a community that has good water supply systems, then you turn on the tap and clean water flows, everyday of the year. This makes it very difficult for many people to appreciate how precious water is. Question What does global water shortage mean? There is not enough water for everyone and every living thing on Earth.

oil, coal, and gas

This pie chart compares the sources used for energy consumption in the U.S. for 2012. Notice that the bulk of the energy used is gained by the burning of fossil fuels. The three types of fossil fuels are petroleum (oil), coal, and natural gas. Only about 14% of our energy use comes from other sources, such as nuclear power and hydroelectric (water-generated power), and alternative sources, such as wind or solar energy. This lesson will focus on nonrenewable energy sources--fossil fuels. Click each tab to learn more about the three types of fossil fuels. Oil Natural Gas Coal Oil is a thick, black, gooey liquid that is also called petroleum. It is found far below the surface, usually between layers of rock. To get oil out, a well is dug. Digging a well is like putting a straw into a can of soda. The oil is then pumped out of the ground by oil pumps, as shown in this image. These pumps work just like sucking soda through a straw. Oil is carried in pipelines and large tanker ships. A refinery changes the oil into products such as gasoline, jet fuel, and diesel fuel. It is also burned in factories and power plants to make electricity. What is a possible hazard that can occur when oil is being transported on tanker ships? An oil spill is a possibility that could be disastrous to ocean ecosystems. For example, in the Deep Horizon oil spill in the Gulf of Mexico in 2010, numerous aquatic animals were injured or killed, and the ecosystem still has not fully recovered. Natural gas is lighter than air. It is made from methane, which is a simple chemical compound made up of carbon and hydrogen atoms. This gas is highly flammable, meaning it can catch fire easily. Natural gas is found near oil in the ground, and like oil, it is pumped by wells that tap into the source and send it to large pipelines. Natural gas is sent through underground pipes, as shown in this image, which go to your home. It is also sent to factories and power plants to make electricity. Other than heating your home, what else is natural gas used for? If you have a gas stove or oven, natural gas is used for cooking. Coal comes in several different forms from hard, black rocks to soft, brown dirt. Some forms burn hotter and cleaner than others. Coal is used to produce more than half of all the electricity in the U.S. In some places, the coal beds are near the ground's surface. We get to the coal by mining for it. The equipment used to mine for coal is shown in this image. Most coal is transported by trains to power plants where it is burned to make steam to produce electricity.

government control

Unfortunately, there is no "stop global warming" button you can push to end the enhanced greenhouse effect. Yet there are things people can do to lower their carbon footprint. Even though Karl encouraged people to do their part to lower their carbon footprint, he was interested to know what the United States and other countries did to regulate greenhouse gases that cause global warming. What he discovered was that the U.S. created the Environmental Protection Agency (EPA) in 1970 to give the federal government power to monitor air quality through the Clean Air Act, which is the federal environmental law that regulates air pollution. Internationally, many countries met in Kyoto, Japan, in 1997 to discuss how to reduce the emission (introduction) of greenhouse gases, especially among developed countries. Developed countries have emitted far more greenhouse gases than developing countries. The end result of this first international meeting was an agreement called the Kyoto Protocol. Since then, countries have continued to meet every few years to discuss the consequences of global warming. Click the tabs below to learn more details about both the Clean Air Act and the Kyoto Protocol. Clean Air Act Kyoto Protocol President Lyndon B. Johnson signs the Clean Air Act in 1967. Below is the historical timeline of how the Clean Air Act developed: 1955 Air Pollution Act: This is the first U.S. law to study air pollution. It provided funding for research. 1963 Clean Air Act: This is the first U.S. law to control air pollution as a part of the U.S. Public Health Service. 1967 Clean Air Act This law allowed the federal government to enforce interstate (among the different states) air pollution. 1970 Clean Air Act This law created the EPA and expanded the federal enforcement, research, monitoring, and standard-setting (acceptable levels of air pollution emissions). 1990 Clean Air Act This law addressed acid rain, ozone depletion (destruction of the ozone layer), and toxic air pollution, and it started tracking greenhouse gas emissions. In the image above, the countries shown in green are committed to reducing greeenhouse gas emissions. The countries in yellow are committed to 0% reduction, which means they have agreed not to expand emissions beyond levels at the time of the agreement. The countries in red are not committed to any reduction. Under the Kyoto Protocol, countries must meet their targets primarily through national measures. However, there are three additional ways that countries can meet their emission targets: Emissions Trading: Emissions are divided into assigned amount units (AAUs). Countries can sell their leftover AAUs to other countries that are over their Kyoto Protocol targets. The Clean Development Mechanism (CDM): Countries with an emission-reduction or emission-limitation commitment can start a project, such as using solar panels for electricity, in a developing country. These projects can earn certified emission reduction (CER) credits, which can be counted toward meeting Kyoto Protocol targets. Joint Implementation (JI): Countries can invest money and/or technology in an emission-reduction or emission-removal project to earn emission reduction units (ERUs), which can be counted towards meeting their targets.

fresh water

Water can be broadly separated into salt water and fresh water. Salt water, found in our oceans and seas, contains salt so it is not fit to drink. In other words, salt water has a high salinity. In simple terms, fresh water is water that has low salinity. It is found in glaciers, lakes, reservoirs, ponds, rivers, streams, wetlands and even underground, referred to as groundwater. Water for domestic and industrial uses comes either from surface water, such as lakes, ponds, and rivers, or from aquifers. An aquifer is a deep, underground water supply that has accumulated over a long period. Recall that fresh water is supplied through the hydrologic cycle, or water cycle, illustrated in this image. The hydrologic cycle is the journey water takes as it circulates from the land to the atmosphere and back again. Fresh water comes from precipitation from the atmosphere, usually in the form of rain, mist, and snow. When this precipitation falls, it finds its way into streams and rivers which run down from mountain tops to low-lying areas. Eventually, this fresh water ends up in bodies of water. Referring to the hydrologic cycle, how does water return to the atmosphere from oceans and lakes? Notice the arrows pointing from the ocean up to the clouds. This represents the process of evaporation. Since water is constantly cycled through our planet, it is considered a renewable natural resource, meaning that our water source is constantly being replenished, or renewed. As long as the amount of water used does not exceed the amount generated by natural processes during the hydrologic cycle, the water supply will remain renewable. Unfortunately, human activities seriously threaten this resource.

water scarcity

Water covers over 70% of the earth's surface, so are we really running out of it? Considering that everyone does not have access to fresh water, we just might be. Less than 3% of water is fresh water, and the bulk of this is trapped in snow and ice and not easily accessible. The rest form the seas and oceans and cannot be used in the same way as fresh water. Only a tiny fraction (0.014%) is surface water, in the form of rivers, lakes and swamps. Global water shortage means there is not enough water for all living things on our planet. Over 1 billion people worldwide lack access to a daily supply of fresh water, and for a total of 2.7 billion water is scarce for at least one month of the year. Water scarcity refers to the absence of safe water in any geographic area for human, animal, and environmental use. Sometimes the terms water shortage and water scarcity are used interchangeably. There may not be a water scarcity in your community, but water scarcity exists in many villages and other areas all over the world. So, on earth, there is most certainly a global water shortage. Question You might think the 3% of fresh water may be enough for all humans and animals on earth. What are some possible factors that have caused this fresh water supply to decrease? Human population explosion, pollution, and urbanization contribute to a decrease in the fresh water supply.

effects of water shortage

Water scarcity is caused by deforestation, human population explosion, climate change, and pollution. All of these causes are directly related to human activities. We are causing a global water shortage, but what are the environmental impacts? Clean, fresh water is an essential ingredient for a healthy human life. When waters run dry people cannot get enough to drink, wash, or feed crops. In addition, inadequate sanitation, a problem for billions of people in undeveloped countries, can lead to deadly diarrheal diseases and other illnesses. Can you remember a disease caused by bacteria in polluted bodies of water that results in severe diarrhea? cholera When water supplies are limited, not just people suffer. Entire ecosystems can be damaged, causing a loss of biodiversity. Recall that biodiversity is the variety of life on earth. For instance, if tiny organisms living in a small lake lose their lake habitat, they will mostly likely lose their lives also. This can result in a loss of certain species. Click the tabs below to learn about the effects of water shortage and understand why it is such a problem. Disease Hunger Damaged Ecosystems In many developing countries, people are forced to drink low quality water from streams, many of which are contaminated. In this image, a group of people bathe in the Hooghly River in India. Years ago, this river was clean and contained a greater amount of flowing water. Now it is barely flowing and contaminated. Less water also means sewage (wastewater) does not flow as well, and mosquitoes are other insects breed on stagnant (not flowing, still), dirty water. The result is deadly malaria and other infections. What is the cause of malaria, and how is it transmitted? Malaria is caused by a protozoan that is transmitted to humans by mosquitoes. Lack of fresh water causes huge sanitation issues. Clinics, local restaurants, public places of convenience, and many other places are forced to use very little water for cleaning. This compromises the health of the staff and people who use the facilities. Question Can you think of a specific ecosystem comprised of shallow water, grasses, and many animals, that would be impacted by water scarcity? Ecosystems that are hit especially hard by water shortage are wetlands or marshes. Since these productive ecosystems contain shallow water most of the time, water scarcity can cause wetlands to dry up permanently.

storm of pollution

What do you think this image represents? Maybe a tornado, hurricane, or blizzard? Although this image taken by NASA from a satellite over central Asia does picture a storm, it's not the type of storm you normally think of. This is a dust storm that blew through parts of Asia in 2007. In this image, the dust appears as pale, tan waves immediately south of a large bank of clouds. The dust mimics the movement of the clouds, and both clouds and dust may have resulted from the same weather system. Dust and other pollutants were swept up by the wind from dry, sandy areas surrounding the South Aral Sea. This created the "perfect storm of pollution" which actually made it all the way to the West Coast of the United States. These massive clouds of dust are hazardous to the health of living things. Particles in the air block out sunlight. People that breathe in the dust may experience respiratory problems. Those that already suffer from conditions such as asthma may experience even more complications. Even though this freaky event was unusual, similar dust storms have occurred since then in different areas all over the world. These events are considered a type of air pollution. Pollution occurs when contaminants are added to the natural environment, creating adverse changes. If pollution is released into the air, it is called air pollution. The substance that is released into the air or atmosphere is called a pollutant. Question Other than dust, what are some other forms of air pollution? Forms of air pollution include smoke, gases produced from industrial processes, and gases produced from burning fossil fuels.

Overpopulation

You know that a zombie apocalypse is pure science fiction, but the problem of overpopulation is real. To understand the concept of overpopulation, your need to know what a population is. Thomas Malthus first proposed the idea that human overpopulation is a problem. A population is defined as all the members of a species that live in a particular location. If the prefix over- is added to the word, you get the idea that too many members of a species are living in a particular location. Overpopulation is a situation in which the number of individuals of a given species exceeds the number that its environment can sustain. This lesson focuses on human overpopulation, and the "particular location" is Earth. So overpopulation is referring to the relationship between the human population and the environment, our planet. The concept of human overpopulation is not a new revelation. Early in the 19th century, the English scholar Reverend Thomas Malthus published "An Essay on the Principle of Population." Malthus hypothesized that human population growth would quickly exceed what the environment was capable of supporting, leading to overpopulation and social problems. Watch this video to learn about Thomas Mathus' predictions on overpopulation. In Malthus' essay, he argued that overpopulation was the cause of many of the social ills observed in the industrial societies of Europe: poverty, malnutrition, and disease could all be attributed to overpopulation. According to Malthus, this outcome was inevitable. Malthus observed that populations were growing faster than available resources, such as food. Thus, if left unrestricted, human populations would continue to grow until they would become too large to be supported by the food grown on available agricultural land. In other words, humans would run out of food and land to grow the food on. As a solution, Malthus urged "moral restraint." That is, he declared that people must practice abstinence before marriage and institute criminal punishments for unprepared parents who had more children than they could support. This solution was very controversial. According to Malthus, the only alternative to moral restraint was certain disaster. This disaster he was referring to included catastrophes such as disease, famine, and war. Transcript Question Taking into account the definition of overpopulation and Malthus' views on the subject, is overpopulation currently a problem on Earth? As of now, many experts agree that overpopulation has not yet occurred, but it most likely will happen in the future.

carrying capacity

You know why the human population has exploded, but can this growth continue? Humans continue to increase in numbers as a result of better living conditions. With more technological advancements comes more people living to a ripe old age. Can the human population continue to grow indefinitely? As in other natural populations, the human population will eventually reach a point at which the environment cannot support any greater size. The unavailability of food, water, and space, or some other necessity acts as a limiting factor for every population and halts further growth. Limiting factors limit population size. The size of a population that can be supported by the environment is called the carrying capacity of the environment. At some point in the future, human population growth must stop because Earth will reach its carrying capacity and will not be able to support any more humans. Graph of a population that has reached its carrying capacity (K). The graph is a visual representation of the growth of a population in nature that has reached its carrying capacity. When limiting factors, such as food and water, run out, the carrying capacity (K) has been reached. Use the graph and your knowledge about human population growth to fill in the blanks below. Click here to begin. Before reaching carrying capacity, the population size is . increasing decreasing not increasing or decreasing Question Has the human population reached its carrying capacity? No, the human population has not reached its carrying capacity. The graph on this page does not represent the human population as of yet but may do so soon.

Future of Air Pollution

You learned about the various types of air pollution, as well as their causes and methods of control. But are these control methods actually working? Is the environment safer for us now than it was before we became aware of the hazards of air pollution? Watch this video that discusses a scientific study published in 2012. It reveals some interesting findings about the "cleaner" environment in the United States. Numerous studies have shown associations between exposure to air pollution and heart and lung disease. But since 1980, air pollution has been declining steadily in the U.S. due to some control measures that were put in place. So, do these air pollution controls in the United States actually prolong life? A study performed by the Harvard School of Public Health looked at the effects on health of particulate matter in air pollution. The researchers wanted to find out if the reductions in air pollution actually caused reductions in adverse health effects. They found an association between reductions in particulate matter and improved life expectancy in 545 counties in the U.S. from 2000 to 2007. It is the largest study to date to find beneficial effects to public health of continuing to reduce air pollution levels in the U.S. They showed that our efforts to control pollution are indeed worth it. Transcript In the United States, how has the control of particulate matter affected human health and life expectancy? A decrease in particulate matter (aerosol) pollution has shown improved health and an increase in life expectancy. Air pollution not only affects human health, it affects the future survival of living organisms. Technology can often find ways to solve environmental problems created by human activities, but technology alone can't solve all the air pollution problems. People must be willing to make lifestyle changes if they want to protect the environment and enjoy good health. Question What can you do to help decrease air pollution? Instead of driving everywhere in a car, you can walk or ride a bicycle. Every small reduction in the release of air pollutants helps.