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AGU Chapman Conference: Megadrought in Dixieland

AGU Chapman Conference: Megadrought in Dixieland

A never-before-seen megadrought made an appearance this morning at the last day of the AGU Chapman Conference. Paul Aharon of the University of Alabama says his latest observations are the first to suggest that drought affected the southeastern United States from about 13,000 to 11,800 years ago – during the so-called Younger Dryas cool period.  Read more

AGU Chapman Conference: “They walked away”

AGU Chapman Conference: “They walked away”

At the AGU Chapman conference today, Yale archaeologist Harvey Weiss took the prize for an abrupt climate change picture worth a thousand words. Excavating an Akkadian palace in Tell Leilan, Syria, in 2006 and 2008, Weiss’s team found one room with a grain storage vessel smashed on the floor. Lying next to it were a standard litre measure used for rationing grain, and the tablet on which a bureaucrat had been recording the rationing. The artifacts date from about 2190 B.C., when cities and towns of the Akkadian empire in Mesapotamia were being abandoned en masse as the region suffered crushing drought.  Read more

AGU Chapman: Could seafloor vents control atmospheric CO2?

AGU Chapman: Could seafloor vents control atmospheric CO2?

As the Earth has alternated between glacial and inter-glacial periods, the steep climatic ups and downs have gone hand in hand with changes in atmospheric carbon dioxide levels. But where was the CO2 going to and coming from? Scientists have pointed to the ocean – currently a vast sponge for the greenhouse gas.  Read more

AGU Chapman: Meridional madness

AGU Chapman: Meridional madness

Today’s theme at the AGU Chapman Conference on Abrupt Climate Change is that big baddie of climatic tipping points, the shutdown (and rebooting) of the Atlantic Meridional Overturning Circulation, or AMOC. Could this massive system go down again? Tom Delworth of NOAA took on that question and offered up some interesting new modelling evidence.  Read more

AGU Chapman: It’s all about the bumps

A scant 21,000 years ago, Columbus, Ohio, was blanketed by the Laurentide ice sheet. Today it is home to the Byrd Polar Research Centre at Ohio State University, where this morning I sat in a glacially air-conditioned lecture hall watching an animation of that sheet flickering rapidly back and forth across Columbus and the rest of the northern parts of the continent. Such strobe-light climate change from the Earth’s past is the focus of the AGU Chapman Conference on Abrupt Climate Change, being held here this week.  Read more