Will climate change lead to widespread hunger and conflict?

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Will climate change lead to widespread hunger and
conflict? David Lobell Feb. 28, 2008 Program
on Food Security and the Environment Stanford
University dlobell_at_stanford.edu
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We know (1)The world is warming
Low CO2 emissions
High CO2 emissions
Average warming from 20 global climate models
(C)
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(2) Crops prefer cooler temperatures
Because warmer temperatures -shorten the growing
season -increase water stress -increase plant
respiration rates
Effect of Temperature on U.S. Corn Yields
(Schlenker and Roberts, 2006)
30C 86 F 35C 95 F
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(3) Some factors will reduce impacts

• -Crops like higher CO2
• Farmers will adapt to new climates, by switching
  to new crop varieties, new locations, etc.

But these factors are unlikely to make climate
change a net benefit, especially beyond 30 years.
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(4) Effects will be worst in poorer regions
Because -they are mostly warmer to begin
with -they have less capacity to adapt
Global change in cereal production resulting from
climate change
3 different climate models (Rosenzweig and Parry,
1994)
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Summary
It is possible but not probable that climate
change will lead to widespread hunger. This will
be more likely if -CO2 fertilization effects
are smaller than we thought -Adaptation is
relatively slow or ineffective -Large numbers
of people remain poor and on the brink of
hunger These last two are effectively choices we
will make about how aggressively to pursue the
goals of climate adaptation and poverty reduction
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Impacts depend a lot on socio-economic assumptions
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Impacts depend a lot on socio-economic assumptions
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Impacts depend a lot on socio-economic assumptions
Future hungry for several socio-economic
scenarios (no effects of climate change)
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Impacts depend a lot on socio-economic assumptions
Future additional hungry from climate change
no CO2 fertilization
warmest
coolest
with CO2 fertilization
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Impacts depend a lot on socio-economic assumptions
Future CO2 for several emission scenarios
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Impacts depend a lot on socio-economic assumptions
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The biggest unknowns are socio-economic
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Will Climate Change lead to widespread hunger and
conflict? David Lobell dlobell_at_stanford.edu
Program on Food Security and the Environment