2. Greenhouse gasses absorb the heat radiated by the Earth’s surface in the troposphere – molecules vibrate caused by the absorbed energy & transform it to longer wavelength radiating more heat (infrared) Most abundant – water vapor and carbon dioxide Water vapor constant past 160,000 years Carbon Dioxide fluctuation – 190-290ppm 1)1750’s increased fossil fuel use 2)Deforestation/clear cutting 3)Cultivation of crops using fertilizers – Nitrous Oxides (denitrification process)

3. Anthropogenic Sources of GHGs

4. Methane is 20x more efficient at radiating heat back to the troposphere So…what’s all the fuss about carbon dioxide ?? Carbon Dioxide makes up 84% of the net emission in the US (a 20% increase from 1990-2004) = ~6 billion metric tonnes!! Methane make up only 9% of the net emission in the US (and had a 10% increase from 1990-2004) 556 million metric tonnes

5. China US Remember this is per capita!!

6. 1)Combustion of fossil fuels – electricity & transportation 2)Waste Incineration – municipal/urban areas 3)Smelting processes – metal ores Sources of CO 2 Emissions

7.  Oxygen isotopes in ice samples (temp.)  Ice cores samples (CO 2 conc) over 16o,000 y.a.  Accurate Temp. measurements – 1860’s on  Mathematical models (computer based) o Average surface temperature on earth is 15°C (59°F) o Currently in an interglacial period (last 10,000 years). How do we get data?

8. o The concentration of CO 2 in troposphere (370 ppm) is higher now than any recorded sample for the last ~160,000 years. o The 20 th century was the hottest century in the past 1,000 years o Since 1861, the average global temperature of the troposphere has risen 0.6°C/1°F

9. Ice Samples: ~200ppm-290ppm Current: ~370ppm Peak in the winter due to cell respiration remaining constant and photosynthesis declining – fluctuates with N. American seasons…. WHY?? CARBON DIOXIDE CONC. Global avg. temp - ~15°C set at 0 on graph Global temp. inc. between 0.3°C and 0.6°C GLOBAL TEMP CHANGE SUMMARY

10.  Shrinking Glaciers (receding)  Average global sea level rise (10-20cm)  Northward Migration of some fish, tree, and other species  Earlier Spring, later Autumn frost SEND ICE! 1979 2003

11. Glacier Bay Park - 1911 Glacier Bay Park - 2000

12. Hurricanes have grown significantly more powerful and destructive over the last three decades due in part to global warming – Kerry Emanuel MIT professor Ivan - 2004 Katrina 2005

15. CHANGE A LIGHT BULB (replace incandescent bulbs with halogen/fluorescent) REDUCE WASTE (3 R’s – means less combustion/incineration of trash) DRIVE LESS (carpool, bike, walk, mass transit) USE LESS HOT WATER (wash cold water) ADJUST THERMOSTATS (turn up in summer, down in winter) TURN OFF ELECTRONICS (lights, stereos, TV’s)