1. The Atmosphere Troposphere- Bottom Layer –0-12 km –Where we live Stratosphere- Second Layer –12-50 km –Ozone layer

3. The Greenhouse Effect The atmosphere traps heat released from the earth Without Atmosphere earth’s average temperature would be -18°C

5. Convection Currents

7. Natural Climate Change Milankovitch Cycles –The shape of the earth’s orbit changes over a 100,000 year cycle Decadal droughts may be caused by 11 year sunspot cycles Climate change may occur over the course of years or decades

9. CO 2 and Temp Petit et al, 1999

12. How global warming works 1. Sun’s energy comes through Earth’s atmosphere 2. Some heat bounces back into space 3. Atmosphere contains some of sun’s warmth, making Earth habitable

13. How global warming works Fossil fuels: stored carbon Carbon Dioxide (CO 2 ) Fossil fuels: stored carbon

14. How global warming works Fossil fuels: stored carbon

15. Mt St. Helens on May 18, 1980 We put 8 Mt St. Helens’ worth of CO2 into our atmosphere every day

16. El Niňo

17. Air Pollution Americans release 147 million metric tons of air pollution/year –Air pollution has been reduced since 1990 by >1million tons/year Sources of Major Pollutants –Mostly from burning of fossil fuels

18. Major Kinds of Pollutants Primary Pollutants: Those that get released in a harmful form. Secondary Pollutants: become hazardous after reactions in the air.

20. Conventional Pollutants: Sulfur dioxide Carbon Monoxide Particulates Volatile Organic Compounds Nitrogen Oxides Ozone Lead