Transcript iPlant-1 - Department of Geological & Atmospheric Sciences

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Global Climate Change:
What About Agriculture?
Eugene S. Takle
Director, Climate Science Initiative
Professor of Atmospheric Science
Department of Geological and Atmospheric Sciences
Professor of Agricultural Meteorology
Department of Agronomy
Iowa State University
Ames, Iowa 50011
[email protected]
iPlant Collaborative
Biosphere II
27 September 2008
PROJECT TO INTERCOMPARE REGIONAL CLIMATE SIMULATIONS
Source: IPCC, 2001: Climate Change 2001: The Scientific Basis
Source: IPCC, 2001: Climate Change 2001: The Scientific Basis
http://www.ncdc.noaa.gov/img/climate/research/2006/ann/glob_jan-dec-error-bar_pg.gif
Source: Jerry Meehl, National Center for Atmospheric Research
IPCC Fourth Assessment Report Summary for Policy Makers
Energy intensive
Reduced Consumption
Energy conserving
Mitigation
Possible
Adaptation
Necessary
TO INTERCOMPARE
REGIONAL
IPCC FourthPROJECT
Assessment
Report Summary
for PolicyCLIMATE
Makers SIMULATIONS
PROJECT TO INTERCOMPARE REGIONAL CLIMATE SIMULATIONS
PROJECT TO INTERCOMPARE REGIONAL CLIMATE SIMULATIONS
Projected changes in
precipitation between
1980-1999 and 2080-2099
for an energy-conserving
scenario of greenhouse
gas emissions
IPCC 2007
Precipitation minus Evaporation for Western US
(25N-40N, 95W-125 W)
R. Seager, et al.,2007. Model Projections of an Imminent Transition to a More Arid Climate in
Southwestern North America. Science, Vol. 316. no. 5828, pp. 1181 - 1184
Projected Changes* for the
Climate of the Midwest
Temperature
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Longer frost-free period (high)
Higher average winter temperatures (high)
Fewer extreme cold temperatures in winter (high)
Fewer extreme high temperatures in summer in short term
but more in long term (medium)
Higher nighttime temperatures both summer and winter
(high)
More freeze-thaw cycles (high)
Increased temperature variability (high)
*Estimated from IPCC reports
Follows trend of last 25 years and projected by models
No current trend but model suggestion or current trend but model inconclusive
PROJECT TO INTERCOMPARE REGIONAL CLIMATE SIMULATIONS*Estimated from IPCC reports
Projected Changes* for the
Climate of the Midwest
Precipitation
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More (~10%) precipitation annually (medium)
Change in “seasonality”: Most of the increase will come in the first half of the
year (wetter springs, drier summers) (high)
More water-logging of soils (medium)
More variability of summer precipitation (high)
– More intense rain events and hence more runoff (high)
– Higher episodic streamflow (medium)
– Longer periods without rain (medium)
Higher absolute humidity (high)
Stronger storm systems (medium)
More winter soil moisture recharge (medium)
Snowfall increases (late winter) in short term but
decreases in the long run (medium)
*Estimated from IPCC reports
Follows trend of last 25 years and projected by models
No current trend but model suggestion or current trend but model inconclusive
PROJECT TO INTERCOMPARE REGIONAL CLIMATE SIMULATIONS
Projected Changes* for the
Climate of the Midwest
Other
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Reduced wind speeds (high)
Reduced solar radiation (medium)
Increased tropospheric ozone (high)
Accelerated loss of soil carbon (high)
Phenological stages are shortened high)
Weeds grow more rapidly under elevated atmospheric CO2
(high)
Weeds migrate northward and are less sensitive to
herbicides (high)
Plants have increased water used efficiency (high)
*Estimated from IPCC and CCSP reports
Follows trend of last 25 years and projected by models
No current trend but model suggestion or current trend but model inconclusive
PROJECT TO INTERCOMPARE REGIONAL CLIMATE SIMULATIONS
Suitability
Index for
Rainfed
Agriculture
IPCC 2007
PROJECT TO INTERCOMPARE REGIONAL CLIMATE SIMULATIONS
Suitability
Index for
Rainfed
Agriculture
IPCC 2007
PROJECT TO INTERCOMPARE REGIONAL CLIMATE SIMULATIONS
Projected changes in
precipitation between
1980-1999 and 2080-2099
for an energy-conserving
scenario of greenhouse
gas emissions
IPCC 2007
US Corn Yields (Bushels/Acre)
Tostle, Ronald, 2008: Global Agricultural Supply and Demand: Factors Contributing to the Recent
Increase in Food Commodity Prices WRS-0801 May 2008. USDA/ERS
Lingering Questions Relating to Food
Production and Climate Change
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What regions now suitable for rainfed agriculture will
become marginally suitable or unsuitable due to
climate change?
What regions now unsuitable for rainfed agriculture
might become suitable?
PROJECT TO INTERCOMPARE REGIONAL CLIMATE SIMULATIONS
Lingering Questions Relating to Food
Production and Climate Change

By how much will technological advances reduce the
impact of climate change on agriculture?
– Continued advances in drought tolerance for corn
– Drought or excess-water tolerance for all crops
– Availability (e.g., water), sustainability and political
acceptance of expanded irrigation for agriculture
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What dietary changes will occur that will
impact demand?
– Relative amount of meat in diets?
– New crops?
– More locally produced food?
PROJECT TO INTERCOMPARE REGIONAL CLIMATE SIMULATIONS
Summary
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Global temperature change of the last 30 years cannot
be explained on the basis of natural radiative forcing
alone. Only when anthropogenic effects are considered
can we explain recent temperature trends
Mitigation efforts, although urgently needed, will have
little effect on global warming until the
latter half of the 21st century
Adaptation strategies should be
developed for the next 50 years
Impact of climate change on global food
production is yet to be evaluated with the
most recent generation of global climate
models
PROJECT TO INTERCOMPARE REGIONAL CLIMATE SIMULATIONS