Natural Temperature variability including green house effect

1
Climate Change

• Natural Temperature variability including green
  house effect
• Human impact on temperatures
• Adaptation, mitigation, suffering

2
Natural Temperature Variability

• Seasons
• Latitudes - altitudes
• Milankovitch cycles
• El Nino cycles

3
How do we know temperatures from long ago?

• Human records actual measurements
• Proxies ice cores, sediment cores for example

4
Greenhouse effect

• What is it?
• Is it bad or good that Earth has a greenhouse
  effect?
• Greenhouse gases carbon dioxide, methane,
  nitrous oxide, halocarbons, water

5
Sources of greenhouse gases

• Carbon dioxide burning fossil fuels and
  forests, making cement
• Methane decomposition of organic matter in
  swampy environments frozen in tundra and ocean
  floor stomachs of cows
• Nitrous oxides bacterial decomposition of
  manure soil denitrification some organic
  fertilizers
• Halocarbons (including CFCs) chemical cooling
  agent foaming agent propellant (phased out by
  Montreal Protocol)

6
Relative strength of GHG (from UNEP)
7
Future of global warming?

• Computer modeling
• United Nations IPCC

8
Intergovernmental Panel on Climate Change

• Established in 1988

• 2,000 scientists from many nations

• Four assessment reports (latest in 2007)

• Policy-relevant but policy neutral

• Won the Nobel Peace Prize (along with Al Gore)

9
IPCC Fourth Assessment Report Conclusions
10
IPCC Fourth Assessment Report Conclusions
Global atmospheric concentrations of carbon
dioxide, methane, and nitrous oxide have
increased markedly as a result of human
activities since 1750 and now far exceed
pre-industrial values determined from ice cores
spanning many thousands of years.
Today 385 ppm Preindustrial 280 ppm
Highest in 650,000 years
11
IPCC Fourth Assessment Report Conclusions
Warming of the climate system is unequivocal, as
is now evident from observations of increases in
global average air and ocean temperatures,
widespread melting of snow and ice, and rising
global average sea level.
12
More GHGs ? Changing Climate ? Very Bad
13
Future?

• Sea level change (3-20 ft rise)
• Coral reef bleaching
• Changes in locations of plants and animals
• Melting of ice caps and glaciers

14
(No Transcript)
15
Sea Ice in Arctic Ocean 1979 and 2003
16
Alaskan glacier1914 and 2004
17
Solutions?

• Adaptation
• Mitigation
• Suffering is inevitable, but how much?

18
Evaluating Solutions
The Need for Adaptation
We are already committed to a certain amount of
warming
Resources must be devoted to adapting to altered
future conditions
Focus on mitigation cannot ignore need for
adaptation
19
Mitigation?

• Limit dependence on fossils fuels
• Plant trees
• Modify methane management

20
Evaluating Solutions
Focus the Nation Choose five priorities for
action

• Invest in the Clean Energy Revolution
• Create Green Jobs, Save Energy
• 3. No New Coal Plants without "Capture and
  Sequestration"
• 4. Cap CO2 Emissions, Share the Auction Revenues
• 5. Build Green Carbon Neutral by 2030
• 6. Jumpstart Low Polluting Biofuel
• 7. Support Stronger Forests
• 8. Tax Global Warming Pollution
• 9. Cleaner Cars, California-Style
• 10. Get Efficient Cut Energy, Save Money

21
Where Are We? Congress
The energy bill is not enough.
60-80 below 1990 emissions by 2050
Environmental Defense
22
Where Are We? States Cities
Taking the lead on the issue