Image courtesy of NASAGSFC Global Climate Change What
Image courtesy of NASA/GSFC
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 gstakle@iastate. edu i. Plant 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 Fourth. PROJECT Assessment Report Summary for Policy. CLIMATE 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 (25 N-40 N, 95 W-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 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 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 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 CO 2 (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)
Grain and oilseed consumption has exceeded production 7 of last 8 years 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 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 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 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 21 st 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
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