Challenges in Assessing Impacts of Extreme Temperatures Under Global Warming

The impact of increasing greenhouse gases will cause the climatological temperature to increase throughout the calendar year. In addition, global climate models (as well as regional models driven by the output from global models) project the variability in temperature will increase as the average temperature warms, greatly compounding the likelihood of extreme heat and droughts. The causes of the increase in temperature variability have been traced to changing land-atmosphere interactions. Unfortunately, the same models that project increasing temperature variance with global warming typically have too much temperature variability in their (control) simulations of present day climate. In this presentation, we analyze the causes of these biases in the control integrations of the climate models and evaluate the consequences for the projections of the changes in temperature variability and extremes due to global warming.