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Rapid Climate Change
Rapid Climate Change
Lauren ElmegreenESP Seminar
April 28, 2006
Lauren ElmegreenESP Seminar
April 28, 2006
Past Climate: Lake Agassiz
Teller, JT and DW Leverington, 2004
Teller, JT and DW Leverington, 2004
IncreasedSeasonality
Winters becomeeven colder
Less heat is transportedto high latitudes
Sea ice is formed inNorthern Atlantic
Thermohaline circulationslows or shuts down
Sea Ice and Abrupt Climate Change
Denton GH et al, 2005
Possible scenario in current conditions…
IncreasedSeasonality
Thermohaline circulationslows or shuts down
Temperature increases
Sea ice is formed inNorthern Atlantic
Winters becomeeven colder
Less heat is transportedto high latitudes
Schmittner, A., M.Latif and B. Schneider, 2005
Future Climate: Models
Latif, M. et al, 2000
Latif, M. et al, 2000
Rapid climate change in the media
• “Britain faces big freeze as Gulf Stream loses strength” The Times (Britain), Dec 2005
• “Failing ocean current raises fears of mini ice age” New Scientist, Nov 2005
• “Shifting currents renew fears of freezing” The Montreal Gazette, Dec 2005
Summary
• Possible reasons for past rapid climate change– Sea ice formation in North Atlantic– Lake Agassiz
• Model predictions for the future– Models predict gradual changes in THC without a
rapid shutdown– Increased salinity may compensate for density
decreases in Atlantic Ocean
References
• CCNet http://www.staff.livjm.ac.uk/spsbpeis/CCNet-homepage.htm• Denton, G.H., et al, 2005. The role of seasonality in abrupt climate
change. Quaternary Science Reviews, 24, 1159-1182.• Gregory, J.M., et al, 2005. A model intercomparison of changes in the
Atlantic thermohaline circulation in response to increasing atmospheric CO2 concentration. Geophysical Research Letters, 32, L12703.
• Latif, M. et al, 2000. Tropical stabilization of the thermohaline circulation in a greenhouse warming simulation. Journal of Climate, 13, 1809-1813.
• Schmittner, A., M. Latif and B. Schneider, 2005. Model projections of the North Atlantic thermohaline circulation for the 21st century assessed by observations. Geophysical Research Letters, 32, L23710.
• Teller, J.T. and D.W. Leverington, 2004. Glacial Lake Agassiz: A 5000 yr history of change and its relationship to the d18O record of Greenland. GSA Bulletin, 116, 729-742.
Gregory JM et al, 2005