Global Warming Evidence for global warming Consequences of global warming Causes of global warming Solutions to global warming Global Warming The IPCC (Intergovernmental Panel on Climate Change) - 2,500 expert scientists from around the world - reports on state of knowledge on global warming - reports in 1990, 1995, 2001 and 2007 - reports edited by governments (particularly US, Saudi Arabia and China) to water down warnings for political reasons 1
Global temperatures are increasing Since 1850 the average temperature has increased by 0.74 o C The 2007 IPCC (International Panel on Climate Change) report showed greater warming than had been predicted in their 2001 report Predicted warming trends Estimates are an additional 2-6 o C by 2100 Many uncertainties, including changes in green house gas emissions <2 o C change per 100,000 yrs between warmest and coldest periods during the pleistocene glaciations 2
Predicted warming trends All of US will warm, eastern US more Utah precipitation will be similar or less (=drier) o C + - Consequences of Global Warming IPCC report April 2007 (http://www.ipcc.ch) In general, determined that global warming is having a more destructive and earlier impact than previously estimated 1. 20-30% of plant and animal species are at risk of extinction with an increase of 2-4 o C 2. Range extensions for many disease vectors 3. Heat waves in cities (causing death) e.g. in Europe in 2003, 27,000 people died from heat 3
Consequences of Global Warming 4. Changes in vegetation ranges (natural and agricultural) (no more Vermont maple syrup) Consequences of Global Warming 5. Changes in seasonal timing and uncoupling of species interactions (Nature 2003) e.g. nesting date, migration, flowering time Example: migrating birds arrive in Europe after the peak in insect abundance, so they are raising fewer nestlings 4
Consequences of Global Warming 6. Increased fire frequency, intensity and area burned associated with warmer temperatures Consequences of Global Warming 7. Increased storm frequency and intensity (somewhat controversial) 5
Consequences of Global Warming 8. Melting glaciers affect local water sources Consequences of Global Warming 9. Rising sea levels Ice sheets are melting much faster than expected (causing alarm) and rising sea levels Warming of ocean waters causes expansion and also contributes to rising sea levels Change in sea level (cm) Predicted rise: 5-34 inches by 2100 6
Consequences of Global Warming : Rising sea levels Consequences of Global Warming 7
The poor developing nations will be hit the hardest Equatorial countries will feel greater effects of climate change than the US or Europe e.g. 840 million in Africa face the biggest risks from drought; rising sea levels threatens >200 million people in the crowded river deltas of Asia and Egypt as swell as small island nations Developing nations less able to withstand the effects of famine and disease Causes of global warming: what controls earth s temperature? Figure : Thermal radiation emitted by earth Solid pink line - radiance in the absence of an atmosphere (mean temp -6 o C) Jagged yellow line - radiance including greenhouse gases (mean temp +15 o C) Shaded areas - radiation absorbed by greenhouse gases Changing the concentration of GH gases will change the temperature balance of earth; Human activity has little affect on H 2 O, but is changing concentrations of other GH gases Radiance (W cm/m 2 sr) 30% 55% 8
Evidence for rising CO 2 Since industrial revolution, atmospheric CO 2 has risen 200 ppm (30%) Evidence for rising CO 2 Many lines of scientific evidence corroborate rise: Air bubbles trapped in ice cores can be used to determine CO 2 levels as well as temperature; records go back thousands of years 9
Evidence for rising CO 2 Many lines of scientific evidence corroborate rise: Direct measurements from air collected on Mt. Loa in Hawaii since 1950 s by Keeling demonstrate seasonal breathing and general increase Where does the CO 2 come from? US biggest emitter followed by Russia and China 10
Where does the CO 2 come from? 350 mya Fossil fuels Where does the CO 2 come from? Pool of CO 2 in atmosphere has increased 30% because of new inputs; ocean pool is also increasing Now 40% increase in land clearing 60% increase in fossil fuel emissions No new inputs into fossil fuel pool CO 2 lifetime in the atmosphere is >100 years, so if we reduced emissions, there is a lag 11
Where does the CO 2 come from? US biggest emitter followed by Russia and China How will warming change CO 2 inputs into the atmosphere? 14% of the global soil carbon pool is in the Arctic Arctic soils are warming fast which will increase decomposition and release large amounts of CO 2 positive feedback As areas warm and dry, forests will be replaced by grasslands and fires will increase, increasing CO 2 release 12
Temperatures are rising (fact) Atmospheric CO 2 is rising (fact) Does the increase in atmospheric CO 2 cause the increase in temperature? Correlations between atmospheric CO 2 and temperature Close relationship between CO 2 and temperature in recent times and over thousands of years Also consistent with first principles (earthlight) 13
Predictions: atmospheric CO 2 and temperature New territory - never has CO 2 been so high How high can we go? Is there a tipping point? 2007 best guess: 1-2 o C temp limit equivalent to 450(-550) ppm atmospheric CO 2 2009 best guess: 350ppm Can we stop this or has the momentum gone too far? Tim DeChristopher Throws Utah Oil And Gas Drilling Leases Auction Into Chaos Associated Press, December 2008 Environmentalist Punked Bush Administration, Hopes To Save Utah Land Huffington Post, February 2009 University of Utah undergraduate Arraignment and rally with James Hansen (NASA) Tuesday April 28, 11am Library Plaza (210 E 400 S) Tim DeChristopher, Land Auction Prankster, Charged With Felonies Los Angeles Times, April 2, 2009 14
Solutions to global warming : create sinks 1. Plant trees - to completely offset inputs, we would have to plant an area twice as big as Australia 2. Protect current forests - keeps CO 2 in forest pool rather than atmospheric pool (is this a long term solution?) 3. In some cases, increased CO 2 in the atmosphere increases photosynthesis and carbon stored in vegetation (not as big a sink as initially hoped) 4. The oceans have absorbed about half of the CO 2 inputs, but this is acidifying the ocean making calcification more difficult (e.g. harder to make shells, coral skeletons) Summary - creating new sinks is not sufficient to offset emissions Solutions to global warming Global CO 2 emissions must be cut by 80% by 2050 (starting now) in order not to exceed 450ppm (tipping point) - maybe not enough Economic estimates by the IPCC say that the economic costs of doing nothing are larger than the costs of reducing emissions. Waiting will exacerbate the problems and increase the costs. 15
Solutions to global warming Global CO 2 emissions must be cut by 80% by 2050 (starting now) in order not to exceed 450ppm (tipping point) How? cap and trade gives economic incentives to reduce pollutants 1. Absolute cap on emissions 2. Allowances to emit are given to companies 3. Companies that exceed their allowance must buy credits from companies that pollute less (=trade) challenges: determining allowances, enforcement, tracking trading example: In US cap and trade on SO 2 emissions in 1990 s will cause a 50% reduction in 30 years Solutions to global warming : reduce emissions Kyoto protocol international agreement to restrict emissions Local examples: California and the governator require fuel efficient cars In 2000 Chicago initiated cap and trade for volatile organic compounds New England states initiated their own cap and trade laws 393 mayors have signed climate protection bills 16
Solutions to global warming : reduce emissions Example: Salt Lake City Since 2001, emissions have been cut by 31% (exceeding the targets set by the Kyoto Protocol by 148%) and saved the city $$$ Fuel efficient cars, new fuels, methane recouped from sewage and landfills, light bulbs, energy efficient buildings, recycling, water conservation World Resources Institute, April 22, 2009 - www.wri.org/usclimatetarges Climate change proposals in the 110th Congress versus Waxman-Markey currently being brought to congress (April 2009) 2005 1990 Waxman Markey to stabilize at 450-550 ppm (old tipping point) emissions must lie in blue area new tipping point =350ppm requires more reductions (now 389ppm) 17
Will reducing emissions reduce the quality of life? Reduce per capita energy use Canada Kuwait Solutions to global warming : reduce emissions 1. Reduce per capita emissions (conservation cheap and effective) 2. Switch to carbon neutral sources (wind solar and geothermal) 18
Solutions to global warming : reduce emissions 1. Reduce per capita emissions (conservation cheap and effective) 2. Switch to carbon neutral sources (wind solar and geothermal) wind is estimated to be the second cheapest form of energy after burning soft coal (not including the environmental costs) Every 20 days the energy in sunlight is equivalent to the entire planetary reserves of coal, oil and gas. Passive and active solar technologies have great promise. Nuclear power does not emit CO 2 Solutions to global warming : reduce emissions 1. Reduce per capita emissions (conservation cheap and effective) 2. Switch to carbon neutral sources a) wind, solar and geothermal (most promising) b) nuclear (possible safety threats) c) biofuels (conversion of plant biomass to fuels: crops, waste advantages: theoretically carbon neutral disadvantages: - using crops as a source (corn, sugarcane) takes land from food production - crops use large energy inputs (fertilizer and machinery); for corn this is 80% Use of waste (by products) or native vegetation might have fewer negative impacts 19
Low-input high-diversity grasslands may give higher yield than corn Tilman et al Science 2006 High diversity - normal diversity of prairie grassland Low input - no fertilizer, plowing, replanting, just mow once a year Biofuels Low input high diversity grasslands may give higher yield than corn Tilman et al Science 2006 Energy (GJ ha -1 ) 100 80 60 40 20 output is 1.25 input input of fossil fuels output is 5.4 input 0 output input output input CORN GRASSLANDS 20
Solutions to global warming : reduce emissions 1. Reduce per capita emissions (conservation = cheap and effective) 2. Switch to carbon neutral sources (wind, solar and geothermal) nuclear (possible safety threats) biofuels (still use lots of fuel, and land) 3. New technologies: e.g. capture CO 2 emitted from fossil fuel burning and inject it into the ground Solutions to global warming What can governments do about it? 1. Eliminate subsidies that encourage emissions (subsidies to the oil industry include regulated prices, R&D grants, subsidized exploration, extraction and processing) 2. Include costs of environmental clean up in calculating consumer costs 3. Pursue cap and trade agreements 4. Support international protocols 21
Solutions to global warming What can individuals do about it? 1. Become informed on the issues (as a scientist and citizen) 2. Vote and let your representatives know your opinion 3. Use public transportation 4. Buy fuel efficient cars 5. Buy energy saving appliances and light bulbs 6. Turn off appliances and lights when not in use 7. Reduce, reuse, recycle (in that order) 8. Buy recycled and local products 9. Educate your friends 10. Have <= 2 children 11. Be aware, be creative Solutions to global warming What can individuals do about it? Some environmental organizations that make it easy to be informed and involved: Environmental Defense Fund Earth Justice Natural Resources Defense Council (NRDC) Union of Concerned Scientists Center for Biological Diversity Save Our Environment 350.org The Wilderness Society Defenders of Wildlife 22