NASA scientists determined eastern U.S. summer daily high temperatures that currently average in the low-to-mid-80s Fahrenheit will most likely soar into the low-to-mid-90s by the 2080s.

The global model, one of the models used in the recently issued climate report by the Intergovernmental Panel on Climate Change (IPCC), was utilized in this study to identify future changes in large-scale atmospheric circulation patterns due to the build up of greenhouse gases. This information was then fed into the weather prediction model to forecast summer-to-summer temperature variability in the eastern United States during the 2080s.

"Relatively cool waters in the eastern Pacific often result in stubborn summer high-pressure systems over the eastern states that block storms, reducing the frequency of precipitation below normal," said study co-author Richard Healy of the Woods Hole Oceanographic Institution. "Less frequent storms result in higher surface and atmospheric temperatures that then feed back on the atmospheric circulation to further reduce storm frequency and raise surface temperatures even more."

The global model simulated rainfall too frequently, so that its surface temperatures were not appropriately sensitive to interannual changes in Pacific sea surface temperatures. "Since the weather prediction model simulated the frequency and timing of summer precipitation more reliably than the global model, its daily high temperature predictions for the future are also believed to be more accurate,” added co-author Leonard Druyan, NASA Goddard Institute for Space Studies and Columbia University.