The Atmosphere

• Troposphere- Bottom Layer – 0-12 km– Where we live

• Stratosphere- Second Layer– 12-50 km– Ozone layer

The Greenhouse Effect

• The atmosphere traps heat released from the earth

• Without Atmosphere earth’s average temperature would be -18°C

Convection Currents

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

CO2 and Temp

Petit et al, 1999

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

How global warming worksHow global warming works

Fossil fuels: stored carbon

Carbon Dioxide (CO2)

Fossil fuels: stored carbonFossil fuels: stored carbon

How global warming worksHow global warming worksHow global warming worksHow global warming works

Fossil fuels: stored carbon

Mt St. Helens on May 18, 1980

We put We put 88

Mt St. Helens’ Mt St. Helens’ worth of CO2 worth of CO2

into our into our atmosphereatmosphereevery dayevery day

El Niňo

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

Major Kinds of Pollutants

• Primary Pollutants: Those that get released in a harmful form.

• Secondary Pollutants: become hazardous after reactions in the air.

Conventional Pollutants:

• Sulfur dioxide

• Carbon Monoxide

• Particulates

• Volatile Organic Compounds

• Nitrogen Oxides

• Ozone

• Lead