extreme climate in the 21 st century noah s. diffenbaugh department of environmental earth system...
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![Page 1: Extreme climate in the 21 st century Noah S. Diffenbaugh Department of Environmental Earth System Science and Woods Institute for the Environment Stanford](https://reader035.vdocuments.us/reader035/viewer/2022062511/5514beb355034640138b5779/html5/thumbnails/1.jpg)
Extreme climate in the 21st century
Noah S. Diffenbaugh
Department of Environmental Earth System Science
and
Woods Institute for the Environment
Stanford University
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IPCC SRES Scenarios
Raupach et al., 2007
A2: > 800 ppm CO2 in 2100
Simulations test difference between:
1961-1989
2071-2099
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General Circulation Model
Australia Government BOM
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Nested High-Resolution Climate Model
Driver Variables• Temperature• Pressure• Winds• Geopotential Height• Specific Humidity
Driver variables passed to nested model at lateral boundaries every 6 model hours
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Walker and Diffenbaugh, 2009
Diffenbaugh and Ashfaq, in review
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• Increases of 100 to 560 % in occurrence and 50 to 550 % in duration
Change in Extreme Hot Event Occurrence
Diffenbaugh et al., 2005
2071-2099minus
1961-1989
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Change in Extreme Cold Events
∆ Extreme Cold Frequency ∆ Extreme Cold Magnitude
2071-2099minus
1961-1989Diffenbaugh et al., 2005
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Poumadere et al., 2005
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Magnitude of 2003
Heat Stress
Giorgi and Diffenbaugh, 2008
2071-2099minus
1961-1989
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Trapp, et al., PNAS, 2007
Change in Severe Thunderstorm Environments
• Inceases in CAPE overcome decreases in shear
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Harshvardhan et al., in revision
Air Stagnation Events
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IPCC SRES Scenarios
Raupach et al., 2007
A1B
Simulation between:
1950-2039
5 ensemble members=> “physically uniform”
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Ensemble Mean
• Exceedence of 1951-1999 3-month maximum value
Diffenbaugh and Ashfaq, in review
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Summary and Conclusions
• High-resolution nested climate models often project larger changes in health-relevant metrics than global climate models.
=> is this a real feature of the climate system?
• Near-term (decadal), local-scale climate prediction is of high value as a climate service, but is at best very challenging (and at worst impossible) from a scientific perspective.