Transcript PPT File - Regional Climate Modeling Laboratory

Climate Change and Possible
Impacts on Soil and Water
Eugene S. Takle
Professor of Agricultural Meteorology, Department of Agronomy
Professor of Atmospheric Science, Department of Geological and
Atmospheric Sciences
Iowa State University
[email protected]
ISU Soil and Water Conservation Club, 12 September 2005
Climate Change
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What is changing?
How much is it changing?
Why is it changing?
How might it affect soil and water?
What should we do about it?
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Source: IPCC, 2001: Climate Change 2001: The Scientific Basis
Source: IPCC, 2001: Climate Change 2001: The Scientific Basis
JJA Daily Maximum Temperature Trends, 1976-2000
“Warming Hole”
˚C
DTmax (JJA)
Surface Energy Balance
Solar
IR
IR
T
Soil
Latent
Conv & Cond
Surface Energy Balance
Solar
IR
IR
T
Soil
Latent
Conv & Cond
Agung, 1963
El Chichon (1982)
Mt. Pinatubo (1991)
Hansen, Scientific American, March 2004
Carbon Dioxide and Temperature
Carbon Dioxide and Temperature
2004
(377
ppm)
Carbon Dioxide and Temperature
“Business as Usual”
(fossil intensive)
2100
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http://www.earth-policy.org/Indicators/CO2/2004.htm
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Source: Jerry Meehl, National Center for Atmospheric Research
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Tropical Atlantic Ocean
Hurricane Power Dissipation Index (PDI)
Sea-surface temperature
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V
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Emanual, Kerry, 2005: Increasing destructiveness of tropical cyclones over
the past 30 years. Nature, 436, 686-688.
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Sea-Surface Temperatures in August 2005
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Weather Underground: http://www.wunderground.com/tropical/
Source: National Center for Atmospheric Research
The planet is committed to
a warming over the next
50 years regardless of
political decisions
Source: National Center for Atmospheric Research
40% Probability
5% Probability
Source: Intergovernmental Panel on Climate Change, 2001 Report
For the Midwest**
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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 Frost-free 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
+ already observed
** North American Regional Climate Change Assessment Program is underway
but results for impacts won’t be available for several months.
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
Hydrologic Budget Components
Simulated by SWAT under Different Climates
Hydrologic budget
components
Calibration
(19891997)
Validation
(19801988)
NNR
(19801988)
CTL
(around
1990s)
SNR
(around
2040s)
% Change (SNR-CTL)
Precipitation
856
846
831
898
1082
21
Snowfall
169
103
237
249
294
18
Snowmelt
168
99
230
245
291
19
Surface runoff
151
128
151
178
268
51
GW recharge
154
160
134
179
255
43
Total water yield
273
257
253
321
481
50
Potential ET
947
977
799
787
778
-1
Actual ET
547
541
528
539
566
5
All units are mm
Yield is sum of surface runoff, lateral flow, and groundwater flow
Climate Change Impacts on Soil and
Water (my speculations)
• Increase in CO2
– increase in water-use efficiency by plants and
accelerated growth
• Increase in night-time temperatures
– Higher night-time respiration by plants
– Higher soil respiration and loss of soil carbon
– Less dewfall
• Increase in daytime maximum temperatures
– More heat waves
Climate Change Impacts on Soil and
Water (my speculations)
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Higher absolute humidity
More freeze-thaw cycles
Decreased mean wind speed
Altered large-scale weather patterns, storm tracks
Changes in precipitation
– Increased amount -> more soil erosion, more nitrate leaching
– Larger fraction of total rain will come in heavy rain events
and may produce more floods and droughts
– Possible changed seasonality
– Possible changed diurnal patterns -> changes in soil
moisture
Mitigation vs. Adaptation:
Since we are already committed to a global
warming of about 2-4o F over the next 40 years
we need to focus on:
• Adaptation to climate change for soil and water
conservation in the next half decade
• Mitigation of continued rise in greenhouse
gases so our (great)n -grand children will have
as many opportunities as we have had.
• More dialog between soil/water/conservation
scientists and climate scientists to help
prioritize climate research efforts.
For More Information
For peer-reviewed evidence supporting these slides
(except some of my speculations), see my online Global
Change course:
http://www.meteor.iastate.edu/gccourse
Contact me directly:
[email protected]
For a copy of this presentation:
http://www.meteor.iastate.edu/faculty/takle/