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Atmospheric CO 2 & Global Warming. Atmospheric Temperature and CO 2 Levels. Predicted vs Observed Temperatures (Solar Radiation). Atmosphere Composition. The Population Explosion.
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The increase in atmospheric carbon dioxide is primarily due to world energy consumption and secondarily due to deforestation.
Fixing Carbon (Carbon Sequestration) • Photosynthesis • 6C02 + 6H2O C6H12O6 + 6O2 • Atmospheric carbon is fixed in the biosphere. • Stable exchanges of @ 110 billion tons of carbon annually
Carbon Imbalance • Atmospheric carbon levels are at the highest level in 20 million years. • Annually between 9 and 10 billion tons MORE carbon is introduced into the atmosphere than is fixed. • Why?
Types of Carbon • Biospheric carbon and Lithospheric carbon (fossil fuels) • General balance of biospheric carbon exchange, EXCEPT for additional atmospheric carbon from deforestation • Between 1 and 2 billion tons per year. • Lithosperic carbon adds @ 8 billion tones of carbon to the atmosphere • 1 gallon of gas releases @ 5 lbs carbon (18-19 lbs CO2).
400,000 Years of Atmospheric Carbon Dioxide Data Atmospheric CO2 (ppm) Hundreds of thousands of years ago
Causes of Global Change(population, proximate/ultimate effects) • Population growth or resource over consumption? • Impact = Population Number * Per Capita Resource Use • US CO2 emissions = ca. 4 tons C/person/year • Chinese CO2 emissions = ca. 0.2 tonsC/person/year • US Impact = 4 ton C /person x ca. 270,000,000 =ca. 1.1 billion tons C/year • Chinese Impact = . 2 ton C /person x 1.4 billion people =ca. 0.3 billion tons C/year
What is the effect on global temperature of doubling the atmospheric concentration of carbon dioxide? The direct effect of heat absorption by the CO2:+ 1 oC The indirect (feedback) effects:+ 0.5 to 3.5 oC • melting ice and snow increases absorption of sunlight (ice-albedo effect) • warmer air holds more water vapor, another greenhouse gas • warmer air results in different cloud characteristics TOTAL: + 1.5 to 4.5 oC
IMPACTS OF GLOBAL WARMING • Threats to Food Production (Diminished Water Supplies) • Human Health Impacts (Heat Waves, Infectious Disease) • Wildfire • Sealevel Rise • Ecological Effects: • Extinction Episode Comparable to K-T Boundary • Spread of Invasive Species • Coral Bleaching • Biome Shift Northwards • Climate Hot Map
Future energy policy will determine this This warming has already occurred 2100 1000 Year
How Serious Is This? • Warming of more than 10C above today’s level will make the Earth warmer than it has been in a million years. • Business-as-usual, with fossil fuel CO2 emissions continuing to increase will mean an additional warming of 20C to 30C this century and will make the Earth a different planet. • At 20C to 30C the new sea level would be 25 meters (80 feet) higher than today. Dr. James Hansen, NASA GISS
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