1. Global Warming
Unit 2: The Atmosphere

2. The Greenhouse Effect
What happens when you get in your car on a hot day?
What would be the benefits of a greenhouse retaining heat?
Sunlight penetrates atmosphere towards earth’s surface
Some is absorbed, and some is reflected back to atmosphere
Of that some is reflected back towards earth, and some escapes into the atmosphere
Gases that absorb and radiate heat are called greenhouse gases
Water vapor, carbon dioxide, CFCs, methane, nitrous oxide
The carpets and upholstery of the car absorb heat—the heat cannot get out.

4. Carbon Dioxide in the Atmosphere
In 1958, Charles Keeling installed an instrument on top of the Mauna Loa volcano to measure Carbon Dioxide
Why does it need to be on top of a volcano?
Varies with the seasons as well (observe on graph)
So how does this affect temperature?
Greenhouse gases absorb heat and keep the temperature on earth warmer.
Modeling – scientists write equations and enter data for variables to predict how factors like temperature and sea level will be affected
Levels are variable other places (near forests)

7. Consequences of a Warmer Earth
Birds are nesting earlier, flowers are blooming earlier
Effects will not be the same everywhere
Melting of sea ice causes sea levels to rise
Wetlands could be flooded, people could lose their homes, beaches could be eroded, salinity of water could increase!
In Britain over 200 species of plants are blooming 55 days earlier than they did just 40 years ago!

8. Consequences Continued
Hurricanes and typhoons become more common
Gulf stream could be cut off – affect weather
Increase in heat-related
deaths
People allergic to pollen
would be at risk for longer
Mosquitoes are enabled –
higher risk for malaria
Droughts become more
frequent
Range of plants/animals change
– increased competition and
invasive species

9. Recent Findings and Reducing the Risk
IPCC – 2500 of world’s leading climatologists from 70 countries
Release regular reports (0.6 degrees Celsius in 20th century)
Kyoto Protocol – 1997, representatives from 160 countries met and set timetables for reducing emissions
In 2001 the U.S. decided NOT to ratify the Kyoto Protocol
Examples: reforestation project
Complicated by economic, political, and social factors
International Panel on Climate Change