Chapter 20: Climate change and ozone depletion March 18, 2014
March 18, 2014 Predicting Climate Change Volcanic eruption 1991 Philippines Cool earth 0.5ºC over 15months, return to normal by 1995 Model accurately predicts Significance?
March 18, 2014 Glacial and interglacial periods Caused by...? Change in elliptical orbit of earth wobble of axis sun spots, solar magnetic cycles volcanic eruptions
March 18, 2014 Current interglacial period Rise in last century?
March 18, 2014 Temperatures in past? Historic temperatures determined by proxy measures > tree ring widths, coral growths, isotope in ice, borehole temperatures Analyze ice cores: levels of CO2 in troposphere correlate with temperature tory.nasa.gov/features/paleoclimatology_oxygenbalance/
3 factors that shape earth's climate: Solar energy Greenhouse effect Ocean *natural cooling March 18, 2014
March 18, 2014 Greenhouse Gases: CO2 CH4 H2O N2O Burning fossil fuels Clearing/burning forests (Deforestation) Planting rice/using inorganic fertilizers (agriculture) Which countries emit most greenhouse gasses? US China EU
March 18, 2014 IPCC: Intergovernmental Panel on CLimate Change Evidence for global warming: Warmer average temperatures 10 warmest years since 1861 happened since 1990 Arctic temperatures rising twice as fast as rest of world glaciers/sea ice melting permafrost melting--release CO2 and CH4 Rising sea levels > melting ice > expanding sea water
Computer Models Predict Effects of Various Factors March 18, 2014
March 18, 2014 Predicted change: Very likely that earth's mean surface temperature will increase by 2.4-5.4ºC between 2000 and 2100 Higher than average temperature at > earth's poles > land > oceans > interior of continents
March 18, 2014 Consequence of Climate Change Happening very fast= no time to adapt > ecosystems can crash More intense storms and hurricanes Spread of infectious disease (malaria) "Tipping point"
Factors that affect earth's temperature Ocean-stores CO2 (less with increasing T) Cloud cover > absorb and release heat into troposphere > reflect sunlight Air pollutants > aerosols (size determines effect) Photosynthesis (net change in CO2 = 0?) methane: swamps and methane hydrates March 18, 2014
Effects of Global Warming March 18, 2014
1. Melting ice and snow less reflection of sunlight (positive feedback) mountain glaciers-source of fresh water melting land based ice (not floating sea ice)-raise sea levels March 18, 2014
2. Rising Sea Levels Predicted raise of 9-88cm in this century > mostly from expansion of sea water Threaten coastal estuaries, coral reefs, lowlands and deltas Floods barrier islands > erosion > less protection from storms Saltwater intrusion Islands? March 18, 2014
March 18, 2014 3. Changing Ocean Currents Distributes heat, stores CO2 in deep sea Cooling in some regions
March 18, 2014 4. Warmer, more acidic seas reduced current = reduced upwelling > decrease 1º productivity > *positive feedback More CO2 --> more dissolved as carbonic acid > reduces carbonate ions (needed by corals, other organisms with shells)
5. Changes in precipitation and weather extremes Affect hydrologic cycle > agriculture > expanding deserts > droughts in one area, more severe flooding/ precipitation in others March 18, 2014
6. Changes in biodiversity Allow some species to expand ranges (warmer) 1 million face premature extinction? > narrow, specialized niche > narrow range of tolerance Ecosystems most likely dirupted > coral reefs > polar seas > coastal wetlands > tundra > high-elevation mountain tops March 18, 2014
7. Agriculture and fish stocks How will climate change affect agriculture? > Shift north (more rain, warmer) > Overlap of soil fertility and climate (?) Decrease in snowfall/glaciers on mountain tops reduce water available for irrigation *Predicted decline in agricultural productivity in tropical/subtropics region > *world's poorest Fish stocks-affected by changes in sea levels > coastal wetlands > aquaculture ponds March 18, 2014
8. People? Heat stress Tropical infectious disease Allergens Flooding/droughts March 18, 2014
March 18, 2014 Climate change: What do we do? mitigation adaptation wait-and-see act now
March 18, 2014 Mitigation Solutions reduce fossil fuel use > improve efficiency > shift from fossil fuels to renewable energy source > Reduce population > reduce poverty Sequester carbon > plant more trees > soil sequestration > no-till cultivation (reduce CO2 N2O release) > inject into coal seams or ocean *these solutions are expensive *unknown consequences (ocean)
Government Roles Carbon taxes/energy taxes Subsidies for efficiency, renewable energy, carbon sequestration, sustainable agriculture Phase out subsidies for fossil fuel, nuclear power, unsustainable agriculture Technology transfer March 18, 2014
March 18, 2014 Kyoto Protocol International meeting: treaty to help slow global wamring 38 participating developed countries (US backed out in 2001) to cut emissions of CO2, CH4, N2O, HFCs, PFCs, SF6 > developing countries exempt for economic development Goal: Reduce GHGs emission by 5% of 1990 levels in commit period from 2008-20012 in developed countries
Kyoto Protocol: How to achieve reductions? Implement national policies on > efficiency > sustainable agriculture > research and use of renewable energy > reduce tax exemptions/subsidies to sectors that emit GHGs > reduce methane--recover and use as energy March 18, 2014
March 18, 2014 Kyoto Protocol GHG Emission Targets + Mechanisms GHG emission targets for countries that range from -8% to +10% of 1990 GHG emission levels Can reach by > Increasing sinks (reforestation, planting new forests) > Actually cutting GHG emission Other Mechanisms > Emission Trading > Clean Development > Joint implementation
Kyoto Protocol: Emission Trading Can sell spare emission units to countries that are over their targets Can sell: > emission units > removal units from reforestation > emission reduction unit by a joint implementation project > certified emission reduction from clean development mechanism project March 18, 2014
Kyoto Protocol: Clean Development Mechanism Countries can partly reach GHG emission reduction by sponsoring ($$$) GHG-reducing projects in developing countries March 18, 2014
Kyoto Protocol: Joint Implementation A country can invest in a foreign country also under the protocol to either remove emissions there or increase carbon sinks *foreign investment + technology transfer March 18, 2014
March 18, 2014 Kyoto Protocol a Success? Of the 37 countries that stuck through, saw 16% reduction in GHG emission. However, global GHG emission continues to rise.
March 18, 2014 Other efforts by nations/companies to reduce energy waste and reduce greenhouse gas emission. EU Japan Canada China California Companies: DuPont, IMB, Toyota, GE, etc.
Preparing for global climate change March 18, 2014
March 18, 2014 Ozone Layer lower stratosphere keeps 95% UV radiation from reaching earth Thinning (depletion) http://www.epa.gov/ozone/science/sc_fact.html
March 18, 2014 Ozone Depletion CFC* (freons) > coolants, propellants, cleaners, fumigants halons HBFCs CH3Br n-propyl bromide hexachlorobutadiene HCl CCl4 CH3CCl3 (methyl chloroform)
Annual Variation in Ozone Levels Thinning over Antarctica during October and November Winter--winds create a polar vortex > water droplets turn in to ice, surface coated with CFC and other chemicals in stratosphere When vortex breaks up--ozone depleted air flows northward to Australia, New Zealand, South America, South Africa Same phenomena in Arctic February-June March 18, 2014
Less ozone = increased UV exposure Increased human health problems Reduced productivity (crops, seafood, trees) Disrupted wildlife (health problems, population of phytoplankton) Increased pollution (acid deposition, photochemical smog, degraded chemicals) Global warming accelerated March 18, 2014
Protecting Ozone Layer stop using ozone depleting chemicals > especially CFCs and their substitutes International cooperation > Montreal Protocol (cut CFC emission) > Copenhagen Protocol (ODC) March 18, 2014
March 18, 2014 Current Events Activity In groups of 3-4, share your articles. Then, pick one that you think is the most interesting/exciting/ controversial/etc. With your group, come up with 2 discussion questions and 3 review questions related to your article. You will lead a 5 minute discussion/review of concepts. When we are done, you will turn in all of your q's + all of your group's article summaries stapled together.
March 18, 2014