Jonathan Overpeck's (University of Arizona) presentation at the January CLIMAS Colloquium on January 24, 2014.
Title: "The emerging new reality of megadrought risk - from the globe down to the Southwest"
Increased drought risk is (and will be) arguably one of the most certain and troubling aspects of anthropogenic climate change for many parts of the world. At the same time, it is emerging in the scientific literature that state-of-the-art climate and Earth system models are not able to simulate the full range of drought, whether decade-scale droughts like seen recently in both the SW US, and Australia, or multidecadal “megadroughts” that eclipse droughts of the instrumental era in both duration and severity. Evidence for this assertion will be examined, particularly as it comes from the paleoclimatic record of several continents, in both semi-arid and wetter regions. The implications for decision-making will also be discussed, including the on-going operational use, in the United States, of no-regrets drought planning strategies that incorporate paleoclimatic data. Fortunately, because droughts will still occur for natural reasons as well as anthropogenic, increased drought preparedness is a clear “no-regrets” climate change adaptation strategy.