A Hard Rain’s A-Gonna Fall

Extreme precipitation in the tropics comes in many forms: thunderstorm complexes, flood-inducing monsoons, and wide-sweeping cyclones like the recent Hurricane Sandy.

Global warming is expected to intensify such precipitation generally, but the rate at which it does so in the tropics has remained unclear. Now an MIT study based on simulations and observations has estimated that with every 1 °C rise in temperature, tropical regions will see their heaviest rainfalls intensify by 10 percent, which could lead to flooding in populous regions.

Paul O’Gorman, an assistant professor of atmospheric science, looked at simulated patterns in various climate models and compared the patterns with actual weather observations from satellites over a 20-year period. He found that climate change has a bigger impact on extreme rainfall in the tropics than it does in other regions. Results from the study are published online in the journal Nature Geoscience.

“Unfortunately, the results of the study suggest a relatively high sensitivity of tropical extreme rainfall to global warming,” O’Gorman says. “But they also provide an estimate of what that sensitivity is, which should be of practical value for planning.”