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Chapter 19 June 1991: Mount Pinatubo (Philippines) exploded Airborne pollutants, deaths, and damage Affected climate temperature James Hansen(NASA) cooled the temp of the earth by )0.5* over a 19th month period. Then the earth would warm The overwhelming scientific consensus is that the earth’s atmosphere is warming rapidly, mostly because of human activities, and that this will lead to significant climate change during this century. Over the past 4.7 billion years the climate has been altered by ◦ Volcanic emissions ◦ Changes in solar input ◦ Movement of the continents ◦ Impacts by meteors Over the past 900,000 years ◦ Glacial and interglacial periods Over the past 10,000 years ◦ Interglacial period, fairly stable climate and steady average global surface temperature Over the past 1,000 years ◦ Temperature stable but began to rise during the last century when forests cleared, fossil fuel burned Over the past 100 years ◦ Temperature changes mostly since 1975 Analysis of radioisotopes in rocks and fossils Plankton and radioisotopes in ocean sediments Tiny bubbles of ancient air found in ice cores from glaciers Temperature measurements taken at different depths from bore holes drilled deep into the earth’s surface Pollen from lake/bog bottoms Tree rings Historical records - 1861 Without the natural greenhouse effect, warms the earth’s lower atmosphere and surface. Solar energy absorbed by the earth radiates into the atmosphere as infrared radiation(heat) 1% of earth’s lower atmosphere is compressed of greenhouse gases- water vapor, carbon dioxide, methane, and nitrous oxide ◦ Cold, uninhabitable earth Since the Industrial Revolution (275 years ago) ◦ CO2, CH4, and N2O emissions higher ◦ Main sources: agriculture, deforestation, and burning of fossil fuels Correlation of rising CO2 and CH4 with rising global temperatures, during past 400,000 years Countries with the largest CO2 emissions- US, China, EU-27 contries, Indonesia, Russia, Japan, India Per capita emissions of CO2 Scientific and economic studies ◦ 2007: Field and Marland 560 ppm by 2050 – 1390 by 2100 Tipping point 450 ppm ◦ 2008: Aufhammer and Carson China’s CO2 emission growth may be underestimated Ice core analysis – 60% of methane emissions ◦ human impact – landfills, raising live stock, extracting fossil fuels ◦ Nitrous oxide – nitrogen fertilizers Intergovernmental Panel on Climate Change (IPCC) 90–99% likely that lower atmosphere is warming 1906–2005: Ave. temp increased about 0.74˚C 1970–2005: Annual greenhouse emissions up 70% Past 50 years: Arctic temp rising almost twice as fast as the rest of the earth ◦ Melting of glaciers and floating sea ice ◦ Prolonged droughts: increasing ◦ Last 100 years: sea levels rose 10–20 cm ◦ ◦ ◦ ◦ Al Gore and the IPCC : Nobel Peace Prize Natural and humaninfluenced factors could have an effect on temperature changes Drop in average cover of summer arctic ice Mathematical models used for predictions Global warming: rapid rate Human factors are the major cause of temperature rise since 1950 Human factors will become a greater risk factor Since 1975- satellite and balloon measurements ◦ Troposphere has warmed ◦ Stratosphere has cooled Scientists have concluded that the rapid rise in global mean temperature could not be the result of increased solar output Solubility of CO2 in ocean water – removes 25-30% of the carbon dioxide pumped into the lower atmosphere by human activities. Some of it converted to insoluble carbonate salts that are buried in the bottom sediments Warmer oceans ◦ Solubility decreases increases atmospheric CO2 ◦ Coral reefs destroyed ◦ Increased acidity –less carbon dioxide absorbed, increases growth of some algae ◦ drop in populations of phytoplankton, Antarctica’s Southern Ocean and the North Atlantic Ocean –decrease in carbon dioxide uptake Warmer temperatures create more clouds by increased evaporation of surface water ◦ Thick, light-colored low altitude clouds: decrease surface temperature ◦ Thin, cirrus clouds at high altitudes: increase surface temperature Effect of jet contrails on climate temperature – they expand and turn into cirrus clouds that release heat into the upper troposphere Aerosol and soot pollutants ◦ light colored sulfate particles, reflect sunlight and cool atmosphere ◦ sulfate particles also cool the lower atmosphere by forming condensation nuclei that form cooling clouds The projected rapid change in the atmosphere's temperature during this century is very likely to ◦ ◦ ◦ ◦ ◦ Increase drought and flooding, shift areas where food can be grown, raise sea levels, result in intense heat waves, cause the premature extinction of many species. Very rapid, global change in climate – projected rapid increase in average temperature in the lower atmosphere Worst-case scenarios ◦ ◦ ◦ ◦ ◦ ◦ Ecosystems collapsing Low-lying cities flooded Wildfires in forests Prolonged droughts: grasslands become dust bowls More destructive storms Glaciers shrinking; rivers drying up Stepped Art Fig. 19-7, p. 507 less moisture in the soil – NPP will decrease stream flows and available water will decline Biodiversity will decrease growth of plants/trees will slow forest and grassland fires will increase some lakes/seas will shrink and disappear, rivers will fail to reach the sea 1-3 billion people will face water shortage dry climate biomes will increase – savannas, chapparal,deserts global warming be worse in the polar regions – exposure of darker land, absorb more solar radiation floating sea ice disappearing – could affect the average rate of precipitation in certain areas Mountain glaciers affected by ◦ Average snowfall, adds to mass in winter ◦ Average warm temperatures- apur their melting during the summer Europe’s Alps ◦ Glaciers are disappearing South America ◦ Glaciers are disappearing Greenland ◦ Warmer temperatures Areas of Glacial Ice Melting in Greenland Largest island: 80% composed of glaciers 10% of the world’s fresh water 1996–2007: net loss of ice doubled Effect on sea level if melting continues Expansion of warm water and melting of land based ice– Water will rise 18-59 cm (0.6-1.9 feet) during this century storm surges of 6 meters (20 feet) accompanying tropical cyclones and tsunamis ◦ Degradation and loss of 1/3 of coastal estuaries, wetlands, and coral reefs ◦ Disruption of coastal fisheries ◦ Flooding of Low-lying barrier islands and coastal areas Agricultural lowlands and deltas ◦ Contamination of freshwater aquifers ◦ Submergence of lowlying islands in the Pacific and Indian Oceans and the Caribbean Maldives- Indian Ocean Melting of permafrost in tundra soils releases methane and carbon di oxide Loss of arctic tundra-reduce grazing lands for caribou Boreal vegetation would replace tundra Melting glaciers, particularly in Greenland Increased rain in the North Atlantic Could add enough fresh water to disrupt the flow of deep and shallow ocean currents Could climate of Northern Europe. N. America and Japan Not thought to be an immediate problem on the ocean currents Heat waves and droughts in some areas- kill people, reduce crop production, expand deserts Prolonged rains and flooding(flash floods) from heavy and prolonged precipitation Will storms get worse? ◦ More studies needed – Saunders and Lea (2008) Hurricanes Katrina and Rita – lost 320 million big trees Most susceptible ecosystems ◦ ◦ ◦ ◦ ◦ Coral reefs Polar seas Coastal wetland High-elevation mountaintops Alpine and arctic tundra Changes in water temperature, relative to coral bleaching threshold 30% of land –based plants and animals will disappear (temp change 1.5-2.5*C) What about ◦ Migratory animals ◦ Forests Some organisms will increase ◦ Insects, Fungi, Microbes Exploding populations of mountain pine beetles Destroy lodge pole pine forests Regions of farming may shift ◦ Decrease in tropical and subtropical areas ◦ Increase in northern latitudes ◦ Overall food productivity would decrease because of less productivity soil ◦ Decrease in food production in farm regions dependent on rivers fed by snow melt Genetically engineered crops more tolerant to drought Deaths from heat waves will increase Deaths from cold weather will decrease Higher temperatures can cause ◦ Increased flooding ◦ Increase in some forms of air pollution, more O3 ◦ More insects, microbes, toxic molds, and fungi Norman Myers – 150 to 200 million environmental refugees in this century To slow the rate of global warming and climate change, we can increase energy efficiency, sharply reduce greenhouse gas emissions, rely more on renewable energy resources slow population growth. Governments can subsidize energy efficiency and renewable energy use, tax greenhouse gas emissions, set up cap-and-trade emission reduction systems, help to slow population growth. Global problem Long-lasting effects Long-term political problem Harmful and beneficial impacts of climate change unevenly spread Many proposed actions disrupt economies and lifestyles Two approaches ◦ Drastically reduce the amount of greenhouse gas emissions ◦ Recognize that some warming is unavoidable and devise strategies to reduce the harmful effects of global warming Will we reach a political tipping point before we reach irreversible climate change tipping points? Input or prevention strategies ◦ Improve energy efficiency to reduce fossil fuel use ◦ Shift from non-renewable carbon-based fossil fuels to a mix of carbon-free renewable energy resources ◦ Stop cutting down tropical forests Output strategy ◦ Capture and store CO2 - Socolow and Pacala ◦ Climate stabilization wedges ◦ Keep CO2 emissions to 2007 levels by 2057 Brown: need to do more ◦ Cut CO2 emissions by 80% by 2020 ◦ 2008 book: Plan B 3.0: Mobilizing to Save Civilization Output solutions ◦ Massive global tree planting – 4 billion need to be planted Wangari Maathai Great Wall of Trees: China and Africa ◦ Plant fast-growing perennials such as switch grass on degraded land which takes carbon dioxide from the air and stores it in the soil. Can be used to produce ethanol SOLUTIONS Global Warming Prevention Cleanup Cut fossil fuel use (especially coal) Remove CO2 from smokestack and vehicle emissions Store (sequester) CO2 by planting trees Sequester CO2 deep underground (with no leaks allowed) Sequester CO2 in soil by using no-till cultivation and taking cropland out of production Sequester CO2 in the deep ocean (with no leaks allowed) Repair leaky natural gas pipelines and facilities Use animal feeds that reduce CH4 emissions from cows (belching) Shift from coal to natural gas Improve energy efficiency Shift to renewable energy resources Transfer energy efficiency and renewable energy technologies to developing countries Reduce deforestation Use more sustainable agriculture and forestry Limit urban sprawl Reduce poverty Slow population growth Fig. 19-13, p. 515 Stepped Art Fig. 19-14, p. 515 Some Output Methods for Removing CO2 from the Atmosphere and storing it Oil rig Tanker delivers CO2 from plant Coal power to rig plant CO2 is pumped down from rig for disposal in deep ocean or under seafloor sediments Abandoned oil field Tree plantation Switchgrass Crop field CO2 is pumped underground Spent oil or natural gas reservoir Spent coal bed cavern Deep, saltwater-filled cavern = CO2 pumping = CO2 deposit Fig. 19-15, p. 516 Carbon capture and storage (CCS) – Several problems with this approach involves removing carbon dioxide from the smoke stacks of coalburning power and industrial plants and storing them somewhere ◦ Power plants using CCS ◦ ◦ ◦ ◦ ◦ More expensive to build None exist Unproven technology Large inputs of energy to work promotes continued use of coal Effect of government subsidies and tax breaks Stored CO2 would have to remain sealed forever: no leaking CCS – large scale geo engineering scheme opposed by scientists because long term effects on earth’s energy flow, chemical cycling processes and vital biodiversity are unknown Injection of sulfate particles into the stratosphere by balloons, large jet planes, giant cannons Huge amounts of sulfur dioxide injected into the atmosphere every 2 years ◦ Would it have a cooling effect? ◦ Would it accelerate O3 depletion? Remove HCl from seawater – reduce ocean acidity. How would it affect the ecology ? Pump up nutrient-rich deep ocean water and cause algal blooms, remove carbon dioxide and emit dimethyl sulfide which will contribute to the formation of low clouds that would reflect sunlight Re-ice the Arctic – 8,000 ice making barges Wrap large areas of the glaciers with insulating blankets Short-term costs lower Local and global economies may be boosted Provide jobs because of new technology associated with alternative energy Less expenses for remediation Strictly regulate CO2 and CH4 as pollutants Cap-and-trade approach-political advantage carbon taxes - levy energy taxes on each unit of fossil fuel that is burned – tax pollution, not payrolls Increase subsidies to encourage use of energyefficient technology Technology transfer-fund the transfer of green technologies to phase out older, energy wasting technologies 1997: Treaty to slow climate change -2200 delegates from161 nations 1st phase – 174 of the world’s 194 countries (but not US) ratifying the agreement by mid -2008. The Kyoto Protocol ◦ Reduce emissions of CO2, CH4, and N2O by 2012 to levels of 1990 ◦ Trading greenhouse gas emissions among countries ◦ Not signed by theUS.(2001) 67% of ppublic upset President G.W. Bush’s reasons-would harm US economy Cap and Trade systems need to have the caps set low to increase value of the tradable allowances 2004: Stewart and Wiener Should be led by the U.S. ◦ New treaty needed Include China, India, Brazil and other developing countries that are getting industrialized and will be soon emitting the more than 50% of the world’s greenhouse gases Cap-and-trade emissions program Set up achievable 10 year goals – to reduce greenhouse gases over the next 40 years Costa Rica: goal to be carbon neutral by 2030 – 78% from hydroelectric,18% from wind and geothermal Norway: aims to be carbon neutral by 2050 China and India must change energy habits U.S. cities and states (27+ DC: solar and wind) taking initiatives to reduce carbon emissions 650 cities around the world, including 453 US cities reduce greenhouse gases Portland, Oregon – 1993-2005 greenhouse gases at 1990 levels Use of energy-efficient appliances and buildings Incentives for consumers to use less energy Has saved California from building 24 new power plants California sued the EPA so that they and 17 other states can set tougher emission standards Major global companies reducing greenhouse gas emissions- reduce 10-65% below 1990 levels by 2010 ◦ ◦ ◦ ◦ ◦ ◦ Alcoa DuPont IBM Toyota GE Wal-Mart $12 million /year saved by using LED’s Fluorescent light bulbs Auxiliary power units on truck fleets – no idling Carbon Disclosure Project Colleges and universities reducing greenhouse gas emissions ◦ Oberlin College, Ohio, U.S. ◦ 25 Colleges in Pennsylvania, U.S. ◦ Yale University, CT, U.S. Largest teach-In Feb 2008-1500 colleges, climate change and sustainability Reduce greenhouse gas emissions as much as possible (50-85% cut in by 2050) to prevent the planet from heating up by 2*C Move people from low-lying coastal areas Limit coastal building Remove hazardous material storage tanks away from the coast Genetically engineer crops more tolerant to drought Stockpile 1–5 years of key foods Waste less water Connect wildlife reserves with corridors Which do you think is the most important ? Develop crops that need less water Waste less water Connect wildlife reserves with corridors Move hazardous material storage tanks away from coast Move people away from low-lying coastal areas Stockpile 1- to 5-year supply of key foods Prohibit new construction on low-lying coastal areas or build houses on stilts Expand existing wildlife reserves toward poles Fig. 19-17, p. 522 Widespread use of certain chemicals has reduced ozone levels in the stratosphere, which allows for more harmful ultraviolet radiation( UV-A and UV-B) to reach the earth’s surface. To reverse ozone depletion, we must stop producing ozone-depleting chemicals and adhere to the international treaties that ban such chemicals. Ozone Thinning ◦ Seasonal depletion in the stratosphere Antarctica and Arctic not in tropics 1930: Midgely ◦ Discovered the first CFC 1984: Rowland and Molina ◦ CFCs (freons)were depleting O3 Others – halons, hydrobromofluorocarbons (HBFC’s), methyl bromide, hydrogen chloride, carbon tetrachloride, methyl chloroform 1988 – less severe ozone thinning over Arctic from February to June, loss of 11-38% When this mass of air breaks up, large masses of ozone depleted air flow south to linger over parts of Europe, N.America,Asia Research ◦ CFCs are persistent in the atmosphere ◦ Rise into the stratosphere over 11-20 years ◦ Break down under high-energy UV radiation Halogens produced accelerate the breakdown of O3 to O2 ◦ Each CFC molecule can last 65-385 years 1988: Dupont stopped producing CFCs – stalled for 15 years(1974) 1995: Nobel Prize in chemistry Sun UV radiation Cl C F Ultraviolet light hits a chlorofluorocarbon (CFC) molecule, such as CFCl3, breaking off a chlorine atom and leaving CFCl2. Cl Summary of Reactions CFCl3 + UV → Cl + CFCl2 Cl + O3 → ClO + O2 Repeated ClO + O → Cl + O2 many times Cl C Cl Cl Cl F Cl Once free, the chlorine atom is off to attack another ozone molecule and begin the cycle again. O O O O Ozone The chlorine atom attacks an ozone (O3) molecule, pulling an oxygen atom off it and leaving an oxygen molecule (O2). O O O O O O O O O A free oxygen atom pulls the oxygen atom off the Cl chlorine monoxide molecule to form O2. O Cl The chlorine atom and the oxygen atom join to form a chlorine monoxide molecule (ClO). O O Fig. 19-D, p. 525 Damaging UV-A and UV-B radiation ◦ Increase eye cataracts and skin cancer Impair or destroy phytoplankton- Antarctic base of food web loss of removal of carbon dioxide from the atmosphere – worsening global warming Effects of ozone depletion Stepped Art Fig. 19-20, p. 524 This long-wavelength (low-energy) form of UV radiation causes aging of the skin, tanning, and sometimes sunburn. It penetrates deeply and may contribute to skin cancer. Ultraviolet Ultraviolet B A This shorter-wavelength (high-energy) form of UV radiation causes sunburn, premature aging, and wrinkling. It is largely responsible for basal and squamous cell carcinomas and plays a role in malignant melanoma. Hair Thin layer of dead cells Squamous cells Basal layer Epidermis Sweat gland Melanocyte cells Dermis Basal cell Blood vessels Fig. 19-E (1), p. 526 Fig. 19-E (2), p. 526 This long-wavelength (low-energy) form of UV radiation causes aging of the skin, tanning, and sometimes sunburn. It penetrates deeply and may contribute to skin cancer. Ultraviolet A This shorter-wavelength (high-energy) form of UV radiation causes sunburn, premature aging, and wrinkling. It is largely responsible for basal and squamous cell carcinomas and plays a role in malignant melanoma. Ultraviolet B Hair Thin layer of dead cells Squamous cells Epidermis Basal layer Sweat gland Melanocyte cells Dermis Blood vessels Basal cell Squamous Cell Carcinoma Basal Cell Carcinoma Melanoma Stepped Art Fig. 19-E, p. 526 Stop producing all ozone-depleting chemicals 60(1980 levels)–100(1950 levels) years of recovery of the O3 layer 1987: Montreal Protocol – 36 nations, cut down 35% emissions between1989-2000 1990 – London – 93 countries 1992: Copenhagen Protocol-191 countries Ozone levels should return to 1980 level by 2068(15 years later than predicted) and 1950 levels by 2108 Substitutes for CFCs are available More are being developed HCFC-22 worst, phase out chemical by 2020 in developed and 2030 in developing countries, 10 years earlier than agreed in 1992 ◦ Substitute chemical ◦ May still be causing ozone depletion