The effects of climate change will likely cause smaller but stronger storms in the United States.
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Thsi is according to a new framework for modeling storm behavior developed at the University of Chicago and Argonne National Laboratory.
Though storm intensity is expected to increase over today's levels, the predicted reduction in storm size may alleviate some fears of widespread severe flooding in the future.
The new approach uses new statistical methods to identify and track storm features in both observational weather data and new high-resolution climate modeling simulations.
When applied to one simulation of the future effects of elevated atmospheric carbon dioxide, the framework helped clarify a common discrepancy in model forecasts of precipitation changes.
"Climate models all predict that storms will grow significantly more intense in the future, but that total precipitation will increase more mildly over what we see today," said senior author Elisabeth Moyer, associate professor of geophysical sciences at the University of Chicago and co-PI of the Center for Robust Decision-Making on Climate and Energy Policy (RDCEP).
"By developing new statistical methods that study the properties of individual rainstorms, we were able to detect changes in storm frequency, size, and duration that explain this mismatch."
While many concerns about the global impact of climate change focus on increased temperatures, shifts in precipitation patterns could also incur severe social, economic, and human costs.
Increased droughts in some regions and increased flooding in others would dramatically affect world food and water supplies, as well as place extreme strain on infrastructure and government services.
Most climate models agree that high levels of atmospheric carbon will increase precipitation intensity, by an average of approximately 6 percent per degree temperature rise.
These models also predict an increase in total precipitation; however, this growth is smaller, only 1 to 2 percent per degree temperature rise.
Understanding changes in storm behavior that might explain this gap have remained elusive.
In the past, climate simulations were too coarse in resolution (100s of kilometers) to accurately capture individual rainstorms.
More recently, high-resolution simulations have begun to approach weather-scale, but analytic approaches had not yet evolved to make use of that information and evaluated only aggregate shifts in precipitation patterns instead of individual storms. ■