The Atmosphere and Human Activity

Which statement is true about stratospheric ozone?

It blocks UV radiation. Stratospheric ozone is an important part of our atmos phere. It protects us against harmful UV radiation

This is called carbon sequestration

It involves capturing and storing the carbon dioxide that comes out of smokestacks and storing it in some other part of the environment

. It can be deadly to living things, including humans.

The World Health Organization states that 2.4 million people die every year from causes directly attributable to air pollution.

Air pollution is the presence

presence of substances in the air that are in high enough concentrations to harm organisms, ecosystems, or materials

They can also decrease

subsidies paid to support fossil fuel use

the primary air pollutant emitted by the burning of oil and coal, by volcanoes, and by some industrial processes

sulfur dioxide Sulfur dioxide is a common byproduct of volcanoes and industrial processes

There is a tremendous body of evidence indicating

that Earth is getting warmer and that the warming trend we see is caused by an enhanced greenhouse effect.

However, we can say with absolute certainty

that global carbon dioxide levels are rising

Up until 2008

the U.S. was the world's biggest emitter of greenhouse gases

in a perfect world

the amount of heat that greenhouse gases absorb is balanced by the amount of heat that leaves Earth's surface

. We see that temperature is closely correlated

with greenhouse gas concentrations in the atmosphere, especially carbon dioxide.

In 2008, China replaced the U.S. in this role.

Many governments call for a new treaty on global warming that will include developing nations like China, which are currently exempt from requirements to reduce their greenhouse gases.

Which of the following resu lted in decreased use of CFCs?

Montreal Protocol The Montreal Protocol resulted in a decrease in the use of CFCs in aerosols and air conditioners.

This has become known as the Kyoto Protocol

. The first phase went into effect in January 2005

Earth's current temperature is about

0.74 °C (1.34 °F)

What are some ways you depend on Earth's atmosphere?

? You have learned that the atmosphere provides you with oxygen, which is essential for your body's well-being. It protects Earth from harmful solar radiation, and it helps keep Earth at just the right temperature—not too hot and not too cold.

There are many substances in air that can be classified as pollutants

Air pollutants are categorized as either primary pollutants or secondary pollutants

2

All of our evidence indicates that the warming we are experiencing now is much more widespread and much more rapid than any other warming that we know of in geologic history.

This would keep Earth's temperatures fairly steady

But an excess of greenhouse gases can raise the temperatures of the planet because more greenhouse gases mean more heat from the Sun is absorbed. This is exactly what happens during an enhanced greenhouse effect.

Carbon Dioxide

Carbon dioxide is emitted by the combustion of fossil fuels. It is the big contributor to global warming, a phenomena associated with a gradual warming of the earth due to the way that increased carbon dioxide levels in the atmosphere trap heat. You will learn more about global warming later in this section.

Slide 4

Increased UV radiation reaching Earth's surface from ozone depletion is harmful to human health and well-being. It can cause worse sunburns, skin cancer, and eye cataracts (a clouding of the eye's lens that can lead to blindness). These effe cts of ozone depletion are definitely harmful to human health, plant production, and wildlife.

Chlorofluorocarbons

Chlorofluorocarbons (CFCs) are also primary air pollutants. They destroy Earth's protective ozone layer, the part of the stratosphere that protects the earth from excessive solar radiation. CFCs were once widely used in refrigerants and spray cans but are now banned from use.

Slide 3

Chlorofluorocarbons (CFCs) are the main culpri ts in destruction of the ozone layer. These substances were used in many applications such as air conditioners and in aerosol spray cans because it was inexpensive to manufacture. In 1974, however, scientists discovered that widespread CFC use was destroying the ozone laye r. Ultraviolet radiation first strikes a CFC or the CFCl3 molecule in the atmosphere and causes a chlorine atom to break away. The chlorine atom then collides with an ozone or the O3 mo lecule and steals an oxygen atom. This leaves a molecule of ordinary oxygen gas and a chlorine monoxide molecule. That chlorine monoxide molecule then reacts with other oxygen atoms, which releases the chlorine so it can begin the process all over. In this way, multiple ozone molecu les are destroyed. Notice in the equations that represent this process, the CFCs break apart the ozone molecules. The free chlorine or Cl atom is then free to attack more ozone. In this cyclic process, a single CFC molecule can destroy 100,000 ozone molecules. The reas on this process is most pronou nced over the poles is that water droplets that freeze in the air temporar ily store the CFCs during the winter months. As these ice crystals absorb radiation from the Sun, the chain reaction begins. This is why ozone depletion happens quicker in the winter and is not usually observed over the tropics

How are computer models used to research global warming?

Climate is very complex and is hard to predict, but with computer models we can make assumptions about what future climates will be like. By studying past climate data and inputting information of future fossil fuel use, we can make predictions about future global warming.

What are some of your day-to-day activities that may contribute to global warming?

Driving cars, using electricity, relying of manufacturing processes that use electricity, etc., are all examples of ways that we depend on fossil fuels and contribute to carbon dioxide emissions.

1

Earth's temperature has gone up and down several times in its long history. There have been ice ages alternating with times of tropical beaches over much of the globe.

Slide 2

Evidence shows that the ozone layer is thinning. It's observed globally, but most pronounced over Antarctica and the Arctic. The lone peak that you see for the year 2002 was during a year of unusually warm weather. This fa lse-color satellite image from 20 06 shows a large area where the concentration of ozone has decreased by 50% or more. This thinning of the ozone layer, termed the "hole" in the ozone layer, was the largest ever observed.

Explain the connection between fossil fuel burning and the rising of global sea levels.

Fossil fuel burning contributes greenhouse gases to the atmosphere, namely carbon dioxide. This leads to an enhanced greenhouse effect, which causes global warming. As Earth warms, ice caps and glaciers melt, causing rises in sea level.

The Consequences of Global Warming

Global warming will have effects on Earth's land, oceans, and life forms. The oceans help moderate Earth's temperatures by absorbing almost half of the carbon dioxide we emit to the atmosphere. Carbon dioxide gas is dissolved in the seawater and becomes incorporated in seafloor sediments, or it is used by marine org anisms to make their shells. We do not know how much more the oceans can absorb, but we do know that the amount of carbon dioxide the oceans can absorb is dependent on the ocean temperature. If the oceans heat up because of global warming, they will begin to release carbon dioxi de back to the atmosphere. This would amplify global warming.

The Consequences of Global Warming

Global warming will also affect glaciers and polar ice caps. For example, the mass of Arctic sea ice has shrunk since the 1970s, as large amounts of it are melting away under warmer temperatures. On average, most glaciers worl dwide are getting smaller. Only 35 of the 150 glaciers found during the middle of the last cent ury in Montana's Glacier National Park are still around

Explain how Earth's temperature is affected by the amount of greenhouse gases in the atmosphere

Greenhouse gases trap heat; they keep infrared radiation from leaving Earth, thus keeping Earth warm. The more greenhouse gases in the atmosphere, the more this trap ping of heat takes place and the warmer Earth gets.

He said it did not make sense to sign the agreement when there were only a few years of it left anyway

However, several U.S. states have passed laws to limit and reduce carbon dioxide emissions in an attempt to curb global warming

What are some ways you impact Earth's atmosphere? Do you think that your day-to-day activities can affect the quality of the atmosphere and affect its life-sustaining functions?

Human activities do have a significant impact on the atmosphere. Factory and vehicle emissions pour gases into the atmosphere that disrupt its natural functioning and impair its quality.

Ozone Depletion

If you've ever had se rious sunburn you know it's not much fun. It is painful and can increase your chances of developing skin cancer. Earth's ozone layer plays an important role in protecting us from excessive levels of UV radiation so that we don't get sunburns in our day-to-day activities, unless we stay outside way too long. Ozone is simp ly a molecule of three oxygen atoms. Ozone near ground level or at Earth's surface comes from fossil fuel combustion. This ground-level ozone is harmful to human health and makes breathi ng difficult. But the ozone that exists in the stratosphere is the good stuff. It keeps about 95% of the Sun's harmful ultraviolet radiation from reaching Earth. Without this layer of stratospheri c ozone, we'd be over-exposed to solar radiation.

Slide 5

In 1987, the Montreal Protocol was signed by 36 nations worldwide. Its goal was to cut emissions of CFCs by 35% between 1989 and 2000. As time progressed, the progress was not sufficient so in 1992, more progressive agreements were reached. Now 180 nations have agreed to strictly control the use of CFCs. Under these restricti ons, scientists estimate that ozone levels should return to their 1980 levels by the year 2068. Sc ientists are continuing to work on phasing out other chemicals that destroy ozone and on findi ng suitable substitutes for those chemicals

They also use data from Earth's ancient climate to make assumptions about the future climate

None of these factors are certain, so computer models give us only predictions based on our best assumptions and present knowledge. Climate is very complex and it is difficult to make exact predictions of future climate.

Ground level Ozone

Ozone is formed by three oxygen atoms combined together. It is a component of photochemical smog and considered another secondary air pollutant. In the stratosphere, ozone is good—it protects us from harmful solar radiation. But at Earth's surface, it is considered a pollutant. It forms when nitrogen oxides, carbon monoxide, and VOCs react in the atmosphere in the presence of sunlight.

Particulates

Particulates are tiny particles of solid or liquid suspended in the air. They reduce visibility and can become trapped in our lungs, causing lung failure, lung cancer, and even death. Some particulates come from natural events like volcanoes, dust storms, or forest fires. Others come from human activities like fossil fuel burning and industrial processes. Particles less than 2.5 micrometers in diameter are called PM2.5. Those between 2.5 and 10 micrometers are called PM10.

PAN

Peroxyacyl nitrate (PAN) is another component of photochemical smog and a secondary air pollutant.

Photochemical Smog

Photochemical smog is a type of smog that forms when nitrogen oxides and VOCs (volatile organic compounds) react with sunlight to produce a number of secondary air pollutants, including ozone and peroxyacyl nitrates (PAN). As traffic increases on sunny days, photochemical smog builds up to peak levels, irritating people's eyes and respiratory tracts.

Will it keep getting warmer and warmer?

Scientists use computer models to make future predictions. These models are based on assumptive future fossil fuel use, and other factors that could influence climate like clouds, the amount of smog in the air, and the role of the oceans.

The Consequences of Global Warming

Sea levels have been rising as temperatures have ri sen. They are projected to rise another 4 to 35 inches during this century—about 2/3 of this from the expansion of water as it warms and about 1/3 of this from melting ice. Rises in sea level would mean flooding of coastal cities, disruption of agriculture and aquaculture, and loss of property and coastal habitats. People in coastal areas would be displaced from their homes as sea levels gradually rose.

Secondary Air Pollution

Secondary air pollutants are not emitted directly. They form when primary air pollutants combine or react with other substances in the environment. Click through the tabs below to learn more about secondary air pollution.

Smog

Smog is a type of air pollutant formed by the combination of sulfur dioxide and smoke. It is harmful to breathe, irritates your throat, and disrupts visibility. Large urban areas like New York, Beijing, and Cairo often have high levels of smog. The image shows a painting by artist Claude Monet. It depicts the Sun trying to shine through the smog-laden air around London in the early years of the Industrial Revolution.

The Consequences of Global Warming

Some forms of wildlife would benefit from mo re warming. A warmer climate could expand the ranges and populations of some plants and anima ls. On the down side, those organisms that benefit from global warming would likely includ e weeds, insect pests, and disease-carrying organisms. Some other organisms would be har med by global warming. The United Nations estimates that one million species could face extinction if global warming continues. This is because many species are not well adapted to changes in temperature. Polar bears are likely to be an early casualty of global warming. The sea ic e they use as platforms for hunting is melting away. They have officially been listed as a thre atened species because of threats to their icy habitat by global warming.

Under what conditions is the greenhouse effe ct beneficial? When is it not beneficial?

The greenhouse effect is natural and it keep s Earth from getting too cold. However an enhanced greenhouse effect, caused by an increase of greenhouse gases by human activity, can lead to too much warming.

3

The magnitude of warming we have experienced in the last century would have taken thousands of years without the onset of the Industrial Revolution and widespread fossil fuel combustion

Governments can also play a role in combating global warming

They can place taxes on greenhouse gas emissions and provide tax breaks on the use of renewable energy.

Sulfur Dioxide

This is a structural representation of sulfur dioxide, a major primary air pollutant. It is emitted from the combustion of oil and coal, since these substances contain natural sulfur. It is also emitted from volcanoes and some industrial processes. It is a colorless gas with an irritating odor. It can turn to sulfuric acid in the atmosphere and return to Earth as a harmful irritating substance called acid rain.

Carbon Monoxide

This is carbon monoxide, a colorless, tasteless, odorless, yet highly toxic gas. It is often emitted from the incomplete combustion of oil or gas. It commonly comes from motor vehicles. Exposure to carbon monoxide in high enough concentrations can lead to death.

Nitrogen Dioxide

This is nitrogen dioxide, also a major primary air pollutant. It is emitted from coal plants and automobiles. It can form a reddish-brown haze layer over the sky and forms nitric acid in the atmosphere, another contributor to acid rain.

Toxic Metals

Toxic metals are also primary air pollutants. Lead, mercury, cadmium, and copper are the main ones. These metals come from the combustion of fossil fuels and from industrial processes. Lead was once a major component of motor vehicle emissions because it was a widely used gasoline additive, put into gasoline to help prevent engine knocking. But government regulations in the 1970s have lead to great reductions in the use of lead in gasoline. New cars now require "unleaded" gasoline. Toxic metals harm living things by accumulating in their bodies and interfering with normal life functions.

As of April 2009

U.S. President Barak Obama had not signed the Kyoto Protocol either.

in the early days of the agreement

U.S. President George W. Bush said that participating in it would hurt the U.S. economy, and so the U.S. did not take federal steps to reducing carbon emissions

Volatile Organic Compounds

Volatile organic compounds (VOCs) are organic compounds that exist as gases in the air. They come from landfills, tobacco smoke, fossil fuel combustion, and materials like paint, gasoline, dry cleaning solvents, and paint thinners. These substances cause cancer, blood disorders and immune system damage.

4

We had millennia of little change in global carbon dioxide levels and then meteoric rises in just a few decades. That has to be influenced by human activity.

Natural levels of carbon dioxide in the atmosphere tend to rise slightly in the fall, when trees are not producing as many leaves.How do you explain this?

When trees are not producing as much leaves, there is less photosynthetic activity, thus less removal of carbon dioxide from the atmosphere. Also, dead leaves that fall to ground begin to decay, and the decay process gives off additional carbon dioxide.

Human activity is leading to

an enhanced greenhouse effect

higher than it was 100 years ago

and the warming trend is continuing.

Primary pollutants

are those that are directly emitted from a source or a process, such as carbon dioxide coming out of the tailpipe of a car

Example greenhouse gases

are water vapor, carbon dioxide, some CFCs, ozone, and methane.

Carbon sequestration can involve

burying carbon in deep rock formations, but this technology is still being researched.

It is caused by

by gases called greenhouse gases, which re-emit infrared radiation down to Earth, warming it in the process

the primary air pollutant formed by fossil fuel combustion and which contributes to global warming

carbon dioxide Carbon dioxide is the byproduct of the burning of fossil fuels

the primary air pollutant formed by the incomplete combustion of coal

carbon monoxide Coal combustion creates carbon monoxide

What chemical element is released from a CFC molecule when the molecule reacts with sunlight?

chlorine The chlorine atom in the CFC molecule is released w hen sunlight hits it. That chlorine atom goes on to destroy ozone molecules

What class of chemicals is most respon sible for destruction of stratospheric ozone?

chlorofluorocarbons CFCs are the most dangerous in terms of the des truction of the ozone layer in the atmosphere

the primary air pollutants involved in destruction of the ozone layer

chlorofluorocarbons CFCs are the primary destructors of the ozone layer

Action items to prevent global warming include:

cut fossil fuel use, especially coal—since this produces carbon dioxide, a major greenhouse gas improve energy efficiency—since this would mean using less energy and less coal in the first place use more renewable energy—such as wind power and solar power—as these do not rely on coal combustion reduce deforestation—cutting down forests removes plants, and plants remove carbon dioxide from the atmosphere through photosynthesis limit urban growth—this would mean reduced energy needs

We know that these rises are caused by

human activity and that carbon dioxide is a powerful greenhouse gas.

In December 1997

more than 2,200 delegates from 161 countries met in Kyoto, Japan to negotiate a treaty on global warming action

carbon dioxide and nitrous oxide are increasing

increasing as a result of fossil fuel combustion and no widespread agreements have called for a reduction in fossil fuel use.

Which of the following is NOT a conse quence of ozone depletion in the stratosphere?

infectious disease Both increased sunburn and increased risk of sk in cancer are consequences of ozone depletion.

Earth's greenhouse effect

is a natural phenomenon

The first way that humans impact the atmosphere

is air pollution

water vapor

is the most common in the atmosphere. The others, however, are becoming more prevalent because of human activity

Global warming

is the observation that Earth's average temperature is gradually increasing

The second way we can deal with global warming

is to look for ways to prevent some of the carbon dioxide we produce from circulating in the atmosphere.

Carbon dioxide is especially rising because

it is produced by combustion of fossil fuels, which people all over the world rely on for energy.

It is beneficial because

it traps heat and keeps Earth from getting too cold

The U.S. did not participate in this stage, and developing countries, like China and India, were excluded from having to reduce greenhouse emissions in the first phase because

it was believed that this would slow their economic development.

the toxic metal that was once a major component of gasoline

lead Lead was once a major component of gasoline

CFCs have recently decreased because

of the Montreal Protocol, an international agreement to ban the use of these chemicals.

the secondary air pollutant that is considered bad at ground- level but good in the upper atmosphere

ozone Ozone is dangerous on the surface but helps block harmful UV radiation is in the upper atmosphere

Countries in green have signed the Kyoto Protocol. Countries in grey have not yet decided, and red countries have no current intentions of signing the treaty.

pg 17 map

Natural Influences on the Atmosphere

pg 4

Human Influences on the Atmosphere

pg 5

the secondary air pollutant t hat forms when nitrogen oxides and VOCs react with sunlight to produce polluted air

photochemical smog Photochemical smog forms when nitrogen oxides and VOCs react with sunlight.

Where is thinning of the ozone layer most pronounced?

poles The ozone layer thinning is seen mostly over the poles.

We have several options for dealing with the potential of increased global warming

prevention, clean-up, and political action. Prevention involves reducing the human activity that contributes greenhouse gases to the atmosphere, namely reducing carbon dioxide emissions, which have risen dramatically since the Industrial Revolution.

the secondary air pollutant form ed by the reaction of sulfur dioxide and smoke

smog Smog is a secondary air pollutant and is a combination of sulfur dioxide and smoke.

It called upon nations to reduce emissions of greenhouse gases by 2012

to at least 5.2% below their 1990 levels