Hurricanes from three million years ago give us clues about present storms

Robert Korty, associate professor in the Department of Atmospheric Sciences at Texas A&M, along with colleagues from China, Norway, and the University of Wisconsin, have had their work published in the current issue of PNAS (Proceedings of the National Academy of Sciences).

The team studied storm development from the Pliocene era, roughly three million years ago, and chose that time period because it was the last time Earth had as much carbon dioxide as it does now, and the changes in climate from it can play a major role in storm formation and intensity.

Using computer models and simulations, the team found an increase in the average intensity during the period and the storms most often moved into higher latitudes -- to a more northward direction.

"There seems to be a limit on how strong these ancient storms might be, but the number getting close to the limit appears to be larger during warmer periods," Korty explains.

"They reached their peak intensity at higher latitudes, following an expansion of tropical conditions with warming. It is consistent with smaller changes in the same patterns that we have observed over recent decades and project to continue over the next 100 years. I think it gives us greater confidence in some trends we are witnessing about how storms may change in future years."

Researchers today know that the oceans continued to be relatively warm during the Pliocene era, though there has been some uncertainty where waters were warmest. Their study found that the increase in average intensity and in the poleward expansion occurred regardless of where the greatest change in temperatures occurred in the Pliocene.

Korty says the study adds more evidence "that future storms are likely to be stronger in their intensity and to remain strong even as they move out of the tropics."