There will be no Noon Balloon Lecture on Tuesday Oct 19 due to midterms.

The next lecture will be on:

Tuesday, October 26 
12:15 p.m. - 1:00 p.m. 
417 Schermerhorn

Richard Seager - The past and future of hydroclimate in southwest North America

Summary: Southwest North America (SWNA) has experienced a series of severe multiyear droughts in the period since European settlement some of which have seriously impacted the social history of the region.

Climate modeling has recently revealed that these droughts were caused by small, naturally occurring changes in tropical sea surface temperatures. The modern era droughts, however, pale in comparison with a series of megadroughts of multidecadal duration during the Medieval period. The megadroughts are clear from tree ring reconstructions and are still visible in the western landscape. The causes of the megadroughts are unknown but I'll speculate on them anyway. As for the future, SWNA is robustly projected to become more arid as a consequence of rising greenhouse gases and global warming and general drying and poleward expansion of the subtropical dry zones. The mechanisms for this are distinct from those of naturally-occurring drought. Drying of SWNA, including Mexico, is going to place severe stress on water resources in a place where existing supplies are already stretched.

Full Fall Noon Balloon Schedule
http://eesc.columbia.edu/student-life/undergraduate-student-life/noon-balloon-lecture-series