Global warming: is the jury still out

1
Global warming is the jury still out?
2
(No Transcript)
3
The star marks the summer of 2003, when thousands
of Europeans died heat-related deaths Stott et
al., Nature, 2004
4
According to listeners of Car Talk
But is it our fault?
5
(No Transcript)
6
Short-term evidence

• The weekend effect
• In cities of northeastern US and Japan, nights
  are warmer during the week than on the weekend, a
  difference correlated best with reduced weekend
  driving.

Forster and Solomon, PNAS, 2003
Forster Solomon, PNAS, 2003
7
Long-term evidence
8
Temperature
9
Greenhouse gases CO2, water vapor, HFCs, N2O,
CH4
10
Consequences for California two scenarios
The do-nothing scenario (high emissions)
The clean-up-our-act scenario (low emissions)
11
(No Transcript)
12
More hot days per year
High emissions
Low emissions
13
Consequences deaths due to heat stress
. . .about 4,700-6,300 deaths could be avoided
in the 2090s by following a lower-emissions
pathway
14
Consequences for the chuckwalla?
Photo by Evan Baker (Occidental 04)
15
Will organisms be able to adapt?

• Depends on
• Suitable genetic variation
• Sufficient time

16
Los Angeles Times Dec. 7, 2004
17
Predicted sea level rise of 8 12 inches by 2100
in San Francisco.
Two causes . . .
18
Consequences for beach dwellers
19
Consequences for water users
Precipitation may actually increase, but
widespread drought is predictedwhy?
20
Decreasing Sierra Nevada snowpack
21
Los Angeles Times, Oct. 3, 2004
And its not just drought in CA that affects CA .
. .
22
Oh nooowhat will happen to the price of food?
23
Grapes in particular are sensitive to heat and
drought
24
Another consequence for California
118 Freeway October, 2003
25
Me thought the woods began to move
26
Some organisms have already undergone range
shifts

• Trees into the tundra
• Cardinals into Alaska
• Turdus migratoriusno longer migratory in
  much of U.S.

• For otherswhich ones?range shifts not an option.

27
Changes in marine fish populations in southern CA
28
Fish populations are in decline in coastal waters
of southern California for many reasonsbut how
are they affected by global warming?
29
Reduced upwellings, particularly in southern
California
Northern CA Southern CA
30
Ediths checkerspot moving north and upward
Or disappearing altogether
31
Is it too late?
Remember the two scenarios . . .
32
(No Transcript)
33
6CO2 6H20 C6H12O6 6O2
Photosynthesis, photorespiration, and the missing
carbon sink
Or why things arent even worse (yet)
34
(No Transcript)
35
LA? No way . . .
36
Carmakers May Test Exhaust Law
But it wont come easy . . .
Companies prepare suit that would challenge
Californias authority to force them to reduce
emissions linked to global warming. Los Angeles
Times, Dec. 7, 2004
37
Acknowledgements Information based on two
scenarios comes chiefly from Emissions
pathways, climate change, and impacts on
California. PNAS 10134, Field et al.,
2004 Also, two publications by the Union of
Concerned Scientists and the Ecological Society
of America Confronting Climate Change in
California (1999) Choosing our future Climate
change in California (2004) Access on web
http//www.climatechoices.org/