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Evidence for the Jumping Jet Hypothesis of abrupt climate Change

Evidence for the Jumping Jet Hypothesis of abrupt climate Change. Evidence of Abrupt Climate Change- DO Events from GISP 2. Warmer. At least 20 DO (Dansgaard-Oeschger) events recorded in the last 120 Kyears (Rahmstorf, 2003) Rapid warming followed by slow cooling then rapid cooling.

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Evidence for the Jumping Jet Hypothesis of abrupt climate Change

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  1. Evidence for the Jumping Jet Hypothesis of abrupt climateChange

  2. Evidence of Abrupt Climate Change- DO Events from GISP 2 Warmer • At least 20 DO (Dansgaard-Oeschger) events recorded in the last 120 Kyears (Rahmstorf, 2003) • Rapid warming followed by slow cooling then rapid cooling (Stuiver and Grooves, 2000) (Stuiver and Grooves, 2001) TIME

  3. Dust In Greenland During AbruptClimate Change Warmer More Dust Time Cold times in Greenland are dustier (order of magnitude) Courtesy of Stephen Barker

  4. High resolution abrupt warming Temperature More Dust Warm Dust Less Dust 50 years Time Cold Dust changes are more abrupt and precede temperature changes Fuhrer, 1999

  5. Scatter Plot of ice core oxygen isotope and calcium concentration More Dust Stadial (Cold) Data Points Interstadial (Warm) Data Warmer [Fuhrer,1999] • Temperature (oxygen isotopes) overlap between regimes but calcium does not • CLIMATE REGIME IS BEST CHARACTERIZED BY ATMOSPHERC DUST LOAD – FACTOR OF 10 change

  6. Ideas that do NOT explain dust changes • Strength of Deposition- Wet deposition is dominant [Steffenson, 1997] • Change in source area- all dust is from Asia [Svenson, 2000] • Change in size of source area- Greenland change is too quick [Fuhrer, 1999] • Stronger winds- sea salts in core change moderately [Mogenson, 2002]

  7. Could the Laurentide Ice Sheet Cause the Jet Stream to Jump? Jet flows to the south of the topography- similar to the Modern day circulation Jet flows to the north of the topography

  8. Force A General Circulation Model with glacial conditions and two different ice sheets Courtesy Camille Li

  9. How does the atmospheric circulation change- Stationary waves

  10. How does the Atlantic JetAnd storm track change? Small Ice Contours = Jet speed (m/s) At 300 hPa Colors = Storm activity (V’T’ at 700 hPa) Big Ice K m/s

  11. Back Trajectories from Greenland Small Ice Back Trajectories From Summit Big Ice Origin (15 days At 500 hPa) The Dust Highway

  12. How sensitive is the transitionin atmospheric circulation to theice sheet topography? Courtesy Joe Barsugli

  13. Conclusions • The dust changes in Greenland during abrupt climate change are more rapid and precede the temperature changes • We speculate these changes indicate a change in the atmospheric circulation regime • A general circulation model shows that the Jet Stream may jump during the glacial in a way which may be consistent with the change in dust loading

  14. Courtesy Stephen Barker

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