SOS 110 Mod 4
What are the reasons why industrial agriculture and livestock production have a large environmental impact?
-Monoculture systems that require large energy and matter inputs and produce large outputs (= pollution) -Fertilizer runoff (nitrogen and phosphorus pollution) -CAFOS -Solution: Biodynamic Farming: where outputs become inputs.
What are the causes of climate change?
-*Climate Change*: climate change is a product of greenhouse gases such as carbon dioxide. Unlike CFCs, most of them are not synthetic, and they are released from the burning of fossil fuels (coal, oil, and natural gas). -Rather than destroying a natural process, like CFCs do, they strengthen one to the point of harm: the greenhouse effect. -cause major problems, as agricultural zones, wind and ocean currents, and precipitation patterns shift. The sea level rises, submerging coastal cities. Many species go extinct, as the climate changes faster than they can adapt. -Unintended chemical side effects of our economy posed a serious threat to all species, including our own. -Industry representatives and free-market fundamentalists fought tooth and nail against conclusive scientific findings, and the public became bewildered in a sea of misinformation. -Governments worked together to find sensible alternatives and more or less solved the problem. (Ozone) Climate change? -Changes in the amount of incoming solar radiation (natural changes in earth's orbit and the sun) -Changes in the long wave radiation emitted back to space (Greenhouse gas concentrations) -Changes in the fraction of solar radiation that is reflected back to space (Albedo) -Global warming - a "thickening blanket of CO2 that traps heat in the atmosphere"
Why is burning biofuels more sustainable than burning fossil fuels with respect to increasing CO2 concentrations in the atmosphere and climate change?
-A biofuel is a fuel that is produced through biological processes, such as agriculture and anaerobic digestion, rather than a fuel produced by geological processes such as those involved in the formation of fossil fuels. -Rate of fossil fuel burning is much faster than the rate at which they are formed by geologic processes. (Time Scale is important).
What can you do to reduce your carbon footprint related to food?
-Eat less meat -Buy local
Review the "Energy on Demand" article and note the major sources of energy in the U.S.
-Energy comes in many forms (mechanical, chemical, electrical, etc.) and from many different sources. -Physics define energy as the ability to do work. Energy is stored in many different things like sunlight (solar), materials (coal, natural gas, wood), and chemical systems (the human body). Einstein helped us realize that all matter is energy and that is also stored in atoms (uranium - nuclear). -Power: defined as the amount of energy used over time. -US uses 20% of world's energy consumption -When it comes to energy, most countries have a breadwinner - the energy source that defines that country. In most countries, it is fossil fuels (coal and natural gas). -Coal is essentially compressed carbon and the United States has a lot of it. When burned coal produces ash, CO2, and energy -he typical coal burning plant can produce an average peak power output of about 500 MW (megawatt). -United States, the total energy production from coal was about 1.6 PWhr and another 1.2 PWhr from natural gas. That is about 70% of the United States electrical energy consumption, but we need about 4.0 PWhr. Even though coal and natural gas is very abundant and not running out for decades (maybe a century), they need help to generate the power we demand. -Nuclear power essentially produces water vapor, electricity, and radioactive waste. It basically uses the breaking of an uranium atom (E = mc2) to produce heat to boil water and then we are back to the steam engine, again. The maximum power output can range from 4 GW to 0.5 GW. US produces -0.8 PWhr/year from nuclear power plants (just under that of natural gas). -you only need a tiny amount of uranium compared to tons of coal and you don't produce CO2 and ash, which is great for the environment. However, nuclear power isn't without its controversies (Fukushima). -fossil fuels and nuclear power are NOT renewable (although nuclear is more slowly depleted than fossil fuels). -Hydroelectric: uses the flow of water to produce electricity (essentially taking advantage of gravity). Renewable. The problem with hydroelectric power is you need to build a dam and create a reservoir, which means that you have to displace land and the environment. -Solar: uses the abundant source of energy from the sun, and does this through two different techniques (photovoltaic and concentrated) Renewable. The sunshine provides about 1 kW of power per square meter. Problem: inefficiency. You need to spend over $15,000 just to retrofit your home for solar use. If you can afford them, solar panels can pay for themselves, in energy savings, in just under a decade. There are photovoltaic solar plants that can produce larger amounts of energy, but they typically produce only 0.1 TWhr per year and take up a large amount of space. Not powerful enough to power large cities, but can power rural towns and individual households. -For big energy from the Sun, you need a solar concentration plant. Concentrated solar power plants use a large area of mirrors to reflect light into a power station where the light is concentrated and is essentially used to boil water like a traditional power plant. Remarkably, concentrated solar power plants can have a large power output. Produce about 1.0 TWhr of energy, which about 50-60% less than that of a coal burning plant. -Solar plant can only run when there is sunlight, which for California is about 3000 sun hours per year, which is quite high. Therefore, the annual energy output is dropped dramatically. This is different for coal, nuclear, and hydroelectric, because they can run 24 hours a day/7 days a week. -if we can store energy more efficiently, then we can move away from the on-demand energy grid. (batteries) -Efficient battery technologies will make the combined efforts of solar, wind, and tidal power much more viable. By working to make more efficient solar technologies, small towns and rural areas can become self-sufficient and large solar collector plants can be feasible to power bigger cities. -Other alternative sources. Radio waves, thermoelectric (engine heat, rotating tires, to produce heat energy via piezoelectric.
What are the environmental and social impacts of mining?
-Environmental damage results from all stages of the process of using mineral resources: from extraction, processing and conversion to products, and disposal. -Disturbed land; mine waste; accidents; -> Solid waste; radioactive material; air, water, soil pollution; -> Noise, pollution of air, water & soil; solid and radioactive wastes. -*Sedimentation*: runoff after heavy rainfall often increases the sediment load of nearby water bodies. a) increase the turbidity of natural waters, reducing the light available to aquatic plants for photosynthesis and also eliminating important food sources for predators and decreasing available habitat for fish to migrate and spawn. b) decrease the depth of streams, resulting in greater risk of flooding during times of high stream flow. -*Water pollution* a) Increased Acidity: Occurs when sulfide-bearing minerals, such as pyrite, are exposed to oxygen or water, and then produce sulfuric acid. At low Ph fish can't breed and may die. b) Metal deposition: Reagents used in mining (Arsenic and Mercury) can create toxic levels of heavy metals in the water. 3) Habitat loss and impacts on biodiversity: a) Mostly, removal of trees, soil erosion and sedimentation in streams. *Social Impacts* -Increased hazards to communities. -Example: Mountaintop removal in northeastern U.S. -Dynamite is cheaper, so it does not create new jobs for miners. Environmental consequences. -Mining minerals funds war and conflict. Ex. diamond mining in Sierra Leone -Conflict Minerals: Tungsten, Tantalum, Tin.
What is the difference between power and energy?
-Power: defined as the amount of energy used over time. -Physics define energy as the ability to do work. -In physics, power is given in units of Watts (W) or Joules (energy) per second. This is typically given as a kilowatt (kW), which is 1000 W. -From this, we can define energy as the amount of power (kW) for some amount of time (hour - hr). Energy is what makes change happen and can be transferred form one object to another. ... Power is the rate at which energy is transferred.
What are examples of reinforcing feedback?
-Reinforcing Feedback: Melting Sea Ice & Albedo Increase in CO2 causes temperatures to increase->Temperatures Increase more->Ice melts in Arctic->Ocean water is exposed->Lower albedo->Less sunlight reflected
What are the unintended consequences of the "green revolution"?
1) Biodiversity Loss: Monoculture: 75 to 95% of our fruit and vegetable varieties have been lost for good. Solutions: seed banks and polyculture. 2) Pollution (Synthetic and natural chemicals): increase since green revolution. Biomagnification through a food chain. (Natural) Eutrophication in freshwater (phosphorus) and saltwater (nitrogen) systems. 30 - 80% of N applied to farmlands escapes to contaminate water systems. Increase in N2O emissions (GHG). 3) Soil Erosion: Soil is being eroded (OUT) faster than it is regenerated (IN) by geological processes. Today, soil is lost 17x faster than it is formed. 4) Health Decline (Too little and too much): -Undernutrition 850 million globally malnourished (not enough nutrients) or undernourished (not enough food to meet basic needs) ~ 14% of world! 25-30 million Americans malnourished (much processed food calorie dense, but nutrient poor) -Overnutrition 1.2 billion people suffer from obesity related illness (33% of Americans are obese) Americans spend $42 billion/yr on losing weight (world needs $24 billion/yr to eliminate hunger globally). 5) Climate Change (CO2 , CH4 , N2O): : CH4 (methane produced by animal ag ruminates) and N2O Emissions (Fertilizer)
Review the article on "Ozone Depletion and Climate Change" and note the different processes of climate change and ozone depletion.
Ozone: made of three oxygen atoms stuck together (instead of two, which is what normal oxygen gas is made of), is vital to life on Earth. It forms a layer in the stratosphere, the second layer up in the atmosphere, that is very good at absorbing ultraviolet (UV) radiation from the Sun. UV radiation severely damages organisms if enough of it reaches the surface. -Synthetic gases known as chlorofluorocarbons (CFCs) -Once in the stratosphere, the CFCs were exposed to UV radiation, which was able to break them down. Free chlorine atoms (Cl) were liberated.. Cl acts as a catalyst in the decomposition of ozone, allowing two ozone molecules to become three oxygen molecules, losing their UV absorbing power in the process. Since catalysts are not used up in a reaction, the same Cl radical can continue to destroy ozone until it reacts with something else in the atmosphere and is removed. -Over the poles, the stratosphere is cold enough for polar stratospheric clouds (PSCs) -PSCs provided optimum conditions for the most reactive chlorine gas of all to form: ClO (chlorine monoxide) -Antarctica was more favourable for ozone depletion than the Arctic, both because its temperatures were lower and because its system of wind currents prevented the ozone-depleting substances from drifting out of the area. -hole in the ozone layer over Antarctica (due to the PSCs), and concentrations were declining in other locations too (due to the basic Cl reactions). -Montreal Protocol: 1987, politicians worldwide decided to ban CFCs. The ozone hole in Antarctica has stabilized, and global stratospheric ozone concentrations have been on the rise since 1993. -*Climate Change*: climate change is a product of greenhouse gases such as carbon dioxide. Unlike CFCs, most of them are not synthetic, and they are released from the burning of fossil fuels (coal, oil, and natural gas). -Rather than destroying a natural process, like CFCs do, they strengthen one to the point of harm: the greenhouse effect. -cause major problems, as agricultural zones, wind and ocean currents, and precipitation patterns shift. The sea level rises, submerging coastal cities. Many species go extinct, as the climate changes faster than they can adapt. -global warming is, paradoxically, cooling the stratosphere, as a stronger greenhouse effect means that less heat reaches the stratosphere. Therefore, as climate change progresses, it will make it easier for the ozone depletion reactions to occur, even though there are fewer CFCs. -HFCs (CFC Replacements) are greenhouse gases of similar strength. They don't deplete the ozone, but, per molecule, they can be thousands of times stronger than carbon dioxide at trapping heat. Currently, their atmospheric concentrations are low enough that they contribute far less forcing than carbon dioxide, but it wouldn't take a large increase in HFCs.
