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Earth 2
Thursday, April 1, 1999
Announcements: The make up exam has been
scheduled for next Tuesday at either 7am or 8 am in Deike
Building
Lecture notes:
GLOBAL WARMING
What We Know--Our Foundation
- 1. Greenhouse Gases are selective
absorbers
- 2. Greenhouse gases are on the increase due to human
activities
- 3. The increase of greenhouse gases should produce CO2 in
the atmosphere
- 4. The drawdown of this CO2 in the atmosphere would take
thousands of years
- 5. Aerosols cause the planet to cool
down
- 6. These aerosols come from an anthropogenic
source (humans are the source)
- 7. The temperature surface of earth has risen .4-.6
degrees Celsius in the last century
What Scientists Believe
Virtually Certain
- The stratosphere will cool
Very Probable
- By 2050 the earth will warm .5-2 degrees Celsius
- With twice as much CO2 in the atmosphere as we have
today, the earth will warm 1.5-4 degrees Celsius
- Precipitation will increase
- Sea Ice will retreat-->a result of the Ice-Albedo
Feedback
- The Northern Hemisphere's Snow Cover retreats
- Sea Level increases 12-40 cm by 2100. This is a result of
1) glacial melting, 2) melting ice caps, 3) heating water
and causing it to expand
- Sun's intensity will vary
Probable
- Summer Mid-Latitude Drying (America's Breadbasket will be
dryer)
- Areas at High Latitude will face increased precipitation
- Some places stay cool--area's where the deep water is
sinking will not warm
- Volcanic Eruptions fill the stratosphere with dust,
therefore causing the earth to cool
Uncertain
- The next 10-15 years are unpredictable
- Regional changes-->some will become more variable,
other will become less
- Severe weather (the prediction of hurricanes)
- Biosphere Feedback
**SCIENTISTS CANNOT TELL CHANGES FROM YEAR TO YEAR,
CHANGES FROM REGION TO REGION, OR EXTREMES THAT MAY OCCUR**
3 Choices to Make
We know that humans change the atmosphere's composition, but
the climate models that predict what affect this may have on our
environment have extreme error. What should we do?
- 1. Do Nothing
- 2. Adapt
- 3. Mitigate--actively step in and do something baout the
CO2 in the atmosphere
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