Peru, Zimbabwe, Bangladesh CO2 atmospheric concentrations since 1957 2009 = CO2 at 387 ppm, rising 2 ppm per year Very clear that C02 concentration is rising GHG changes over past 1000 yr Since the Industrial Revolution (ca. 1750): CO2: 280ppm 387 ppm (40%) CH4: 690ppb 1750ppm (151%) N2O: 269ppb 315ppb (17%) ?hockey stick? growth Unprecedented high levels of GHG Coincides with industrial revolution Temp record extended by ?proxy? measures (tree rings, corals, ice cores, documents) 20th century warmest since 1000AD Rising GHG aren?t the only things effecting temps; but at least 80% can be explained by GHG levels Long-view? At least 400,000 years since we?ve had the same levels as now Colombia, 60 million yrs ago. Peak warm period: CO2 >1200 ppm Higher concentrations then Very warm climate, tropical forests everywhere; very different world then we now know Titanoboa >1 ton. 42 feet. Summary of scientific consensus: Recent 30 years warmer than global average temperature for 1,000?s of years Present GHG concentrations highest in >400,000 years (~387 ppm CO2, rising 2 ppm/year) Human activities largely driving change Summary of scientific uncertainties: How great a temperature rise? How fast? Effect on precipitation? Will feedback loops dampen or amplify change? Negative feedback loop ? increasing clouds could damped change How will different regions of the planet be affected? How will society respond to threat? Future Emissions Scenarios (IPCC 2007): ?A? scenarios: rapid economic growth emphasis on industrial economy, world pop ~ 9 billion, reliance on fossil fuels, but improved efficiency. Higher C02 emissions, ?business as usual?, still rely of fossil fuels, modest improvements ?A1? ? equal prosperity, assuming that the 3rd world catches up, industrializes, grows economies etc ?A2? ? uneven growth, poor countries will always lag behind rich countries ?B? scenarios: emphasis on service & info economy, world population ~9 billion, shift to renewable, more wealth based on service, restructure economy, substantial shift to renewable. ?B1? ? equal prosperity, , assuming that the 3rd world catches up, industrializes, grows economies etc ?B2? ? uneven growth, poor countries will always lag behind rich countries Projected temperature changes: +1.4 to +5.8°C (+2.5 to +10.4 °F) SRES = Special Report on Emissions Scenarios, IPCC 2007 Same scenarios translated into temperature changes Gray areas = extremes Take home message: a lot of variability, has to do with science and how we?re responding Projected impacts of global warming (emphasis Global South) PERU: biggest expanse of tropical glaciers in world. Glaciers: provide drinking water to 17 million people most of the coast is desert, so depends on the glaciers for drinking water hydroelectric power supplies 70% of Peru energy irrigation for 44% of commercial crops Glacial area of Peru declined 22% 1960-2000 Some glaciers retreat 200? per year Really fast for a glacier Lima, Peru (8 million people in desert) Melting glaciers is currently providing super abundance of water, but what will happen in the future? Future cost of alternative water $4.5 billion Future cost of geothermal energy $1.5 billion Zimbabwe: environmental change and health effects In trouble in terms of malaria Biological amplification of risk (e.g. 3% ? temp ?30-100% ?mosquito abundance) (Patz & Olson 2006) Most of the population lives in the middle of the country Red = high risk for malaria Blue and yellow = low risk [Das Gupta ? have to be careful, we can?t assume exactly what the impacts are going to be, nature doesn?t always respond in a predictable way] Sea Level Rise due to Global Warming IPCC (2007) estimates that sea level will rise 0.2-0.6 m between 1990 and 2100 Sea level is already rising, as ocean heats up it expands Potential Impact of sea-level rise on Bangladesh Today: total population is 112 million, total land area is 134,000 km2 Same size as Wisconsin, very densely populated country Impact: flooding coastlines, intensifying storms A lot of the population lives on the coast A1 scenario = 0.9 m rise by 2100; 17 million affected; 25% land area submerged Ground Zero for Climate Change: Bangladesh Turns Attention to Climate Change, PBS, 3/08 http://www.pbs.org/newshour/video/module.html?mod=0&pkg=28032008&seg=3 Study questions: Category V storm in 2007: 3,200 deaths [vs. Category V storm in 1991: 140,000]. Why fewer deaths? Early warnings and schools used as shelters Why is Bangladesh so vulnerable to climate change? Pollution from GHG. Many live just 30ft above sea level, rivers swell from melting glaciers flooding and erosion How is architect M. Rezwan helping reduce some Bengalis? vulnerability to climate change? Floating community, live on the water; converting boats to schools, floating power stations, solar panel powered ? 12,000 students; bicycle powered irrigation pumps According to Dr. Raman, how should high greenhouse-gas emitting countries (e.g. U.S.) compensate Bengali villages? Carbon credits for ?climate refugees? from high emitting companies or countries; likened them to WWI/II European refugees who had to move, superpowers who cause this damage should pay for the move Economic impacts? ~~5% of global GDP per year by 2100 But uneven. Developing countries most vulnerable and may be hardest hit. The Precautionary Principle Where there are threats of serious, dangerous or irreversible damage, lack of full scientific certainty shall not be used as a reason for postponing measures to prevent environmental degradation. Particularly if there are dangerous elements Uncertainty served as reason for inaction Downside to Precautionary Principle? (p. 158, Lomborg) Carried to an extreme Traffic accidents would be greatly reduced if we drove 5 mph but that has too much of a cost
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