K.D. Nelson Lecture Series – Dr. Benjamin Cook

The Department of Earth & Environmental Sciences in the College of Arts and Sciences presents the K.D. Nelson Lecture Series featuring speaker Dr. Benjamin Cook from Columbia University. His talk is titled: The Past, Present, and Future of Megadrought in Western North America. 

Western North America is currently experiencing a severe, widespread multi-decadal “megadrought” that is having significant negative impacts on people, ecosystems, and water resources across the region. Notably, however, such events are common in the paleoclimate record over the past two millennium. How extreme, then, is the current event compared to past megadroughts? And how, if at all, is climate change contributing to the current megadrought, and possible future events? Tree-ring records of past drought variability demonstrate that the current megadrought is the most severe such event of the last 1200 years, comparable only to the major megadroughts of the pre-1500 CE era. Much like previous megadroughts, the ongoing event is forced primarily by an extended period of cold sea surface temperatures in the eastern tropical Pacific. However, climate change, manifesting through warmer temperatures and increased evaporative losses to the atmosphere, has likely contributed ~40% of the magnitude of this event, turning what would have otherwise been a moderate drought into one of the most extreme events of the Common Era. Climate model projections suggest that the risk of similar events will increase substantially with future warming, though some of the worst impacts can likely to be mitigated by reducing emissions.