soil mechanics

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Agriculture and Climate Change

• Eugene S. Takle
• Agronomy Department
• Geological and Atmospheric Science Department
• Iowa State University
• Ames, Iowa 50011
• gstakle_at_iastate.edu

Underwriting/Marketing Seminar, 30 March 2005
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Outline

• Evidence for global climate change
• Future atmospheric carbon dioxide concentrations
• Simulations of global climate and future climate
  change
• Impacts of climate change for the US Midwest
• Climate surprises
• Social inequities and ethical issues
• surrounding climate change
• Summary

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Carbon Dioxide and Temperature
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Carbon Dioxide and Temperature
2005
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Carbon Dioxide and Temperature
2040
(440 ppm)
2005
(375 ppm)
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Carbon Dioxide and Temperature
Stabilization at 550 ppm
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Carbon Dioxide and Temperature
Business as Usual (fossil intensive) 2100
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Associated Climate Changes

• Global sea-level has increased 1-2 mm/yr
• Duration of ice cover of rivers and lakes
  decreased by 2 weeks in N. Hemisphere
• Arctic ice has thinned substantially, decreased
  in extent by 10-15
• Reduced permafrost in polar, sub-polar,
  mountainous regions
• Growing season lengthened by 1-4 days in N.
  Hemisphere
• Retreat of continental glaciers on all continents
• Poleward shift of animal and plant ranges
• Snow cover decreased by 10
• Earlier flowering dates
• Coral reef bleaching

Source Intergovernmental Panel on Climate
Change, 2001 Report
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Mann, M. E., R. S. Bailey, and M. K. Hughes,
1999 Geophysical Research Letters 26, 759.
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El Chichon (1982)
Agung, 1963
Mt. Pinatubo (1991)
Hansen, Scientific American, March 2004
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Source Jerry Meehl, National Center for
Atmospheric Research
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Source National Center for Atmospheric Research
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The planet is committed to a warming over the
next 50 years regardless of political decisions
Source National Center for Atmospheric Research
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Source Intergovernmental Panel on Climate
Change, 2001 Report
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40 Probability
5 Probability
Source Intergovernmental Panel on Climate
Change, 2001 Report
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Climate Change Projected for 2100
Rapid Economic Growth
Slower Economic Growth
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Source IPCC, 2001 Climate Change 2001 The
Scientific Basis
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Source IPCC, 2001 Climate Change 2001 The
Scientific Basis
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IPCC Summary for Policy Makers

• An increasing body of observations gives a
  collective picture of a warming world and other
  changes in the climate system

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IPCC Summary for Policy Makers

• An increasing body of observations gives a
  collective picture of a warming world and other
  changes in the climate system
• Emissions of greenhouse gases and aerosols due to
  human activities continue to alter the
  atmosphere in ways that are
  expected to affect the climate

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IPCC Summary for Policy Makers, contd

• Confidence in the ability of models to project
  future climate has increased

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IPCC Summary for Policy Makers, contd

• Confidence in the ability of models to project
  future climate has increased
• There is new and stronger evidence that most of
  the warming observed over the last 50
  years is attributable to human
  activities

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IPCC Summary for Policy Makers, contd

• Anthropogenic climate change will persist for
  many centuries

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IPCC Summary for Policy Makers, contd

• Anthropogenic climate change will persist for
  many centuries
• Further action is required to address remaining
  gaps in information and understanding

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Climate SurprisesLow Probability but
High-Impact Events

• Breakdown of the ocean thermohaline circulation
  (Greenland melt water)
• Breakoff of the West Antarctic Ice Sheet

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Antarctica
Greenland
Ice Volume
0
Warm
Cold
Climate
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Meltwater flows into a large moulin on
Greenland and down to the bedrock to
"lubricate" the sheet
BBC News World Edition http//news.bbc.co.uk/2/h
i/science/nature/2558319.stm
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For the Midwest

• Warming will be greater for winter than summer
• Warming will be greater at night than during the
  day
• A 3oF rise in summer daytime temperature triples
  the probability of a heat wave
• Growing season will be longer (8-9 days longer
  now than in 1950)
• More precipitation
• Likely more soil moisture in summer
• More rain will come in intense rainfall events
• Higher stream flow, more flooding

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Sub-Basins of the Upper Mississippi River Basin
119 sub-basins Outflow measured at Grafton, IL
Approximately one observing station per
sub-basin Approximately one model grid point per
sub-basin
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RegCM2 Simulation Domain
Red global model grid point
Green/blue regional model grid points
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Ten-Year Mean Monthly Stream Flow Generated by
the RegCM2 Regional Climate Model Driven with
HadCM2 Global Model Results for the Contemporary
and Future Scenario (2040s) Climate
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Relation of Runoff to Precipitation for Various
Climates
More precip goes to streamflow in a future climate
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Warming Hole
C
DTmax (JJA)
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Source IPCC, 2001 Climate Change 2001 The
Scientific Basis
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Social Inequities due to Climate Change

• Agricultural production
• Freshwater availability
• Sea-water innundation
• Intergenerational equities

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Social Inequities due to Climate Change

• Agricultural production
• Freshwater availability
• Sea-water innundation
• Intergenerational equities

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Impact on US Agriculture(my speculations)

• The US is a large enough country at a high enough
  latitude that it will have regional winners and
  losers
• Areas now marginal for agriculture may become
  less suitable
• Some areas now having abundant water but limited
  growing seasons may be winners
• Areas with good soils and robust climate, like
  Iowa, may be impacted less
• The US Midwest may experience more variability
  from
• year to year, which would make agricultural
  yields
• more variable (flooding, water-logging, drought)
• Changes in consumption and agricultural
  production
• in other nations may affect US agriculture more
• than changes to US climate
• Environmental refugees?

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Social Inequities due to Climate Change

• Agricultural production
• Freshwater availability
• Sea-water innundation
• Intergenerational equities

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http//www.grida.no/climate/vital/37.htm
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http//www.grida.no/climate/vital/38.htm
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Social Inequities due to Climate Change

• Agricultural production
• Freshwater availability
• Sea-water innundation
• Intergenerational equities

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Sea-Water InnundationExample The Maldives

• Area 115 square miles
• Population 143,000
• Highest point 20 ft above sea level

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Social Inequities due to Climate Change

• Agricultural production
• Freshwater availability
• Sea-water innundation
• Intergenerational inequities

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Intergenerational Inequities

• Sustainable Development To meet the needs of
  the present without compromising the ability of
  future generations to meet their needs.
• Energy sources?
• Non-renewable earth resources?
• Agricultural productivity?
• Fresh water supplies?
• Heavy metal contamination of soil
• and water?

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Summary

• Climate change is real and we need to be doing
  something about it
• The longer we wait, the fewer our options
• Regional patterns of warming will be complicated
• Climate surprises cant be discounted
• Climate change will create regional
• agricultural winners and losers
• Climate change carries ethical
• implications

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For More Information

• See my online Global Change course
• http//www.meteor.iastate.edu/gccourse
• Contact me directly
• gstakle_at_iastate.edu
• http//www.meteor.iastate.edu/faculty/takle/