How Will Future Hurricanes Respond to Climate Change?

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There is no question the recent uptick in hurricane number and intensity is at least partially influenced by climate change. Why and how much will be the subject of a new long-term study unveiled last week by the National Center for Atmospheric Research (NCAR) and National Science Foundation (NSF); working with government agencies and several businesses in the insurance and energy industries, NCAR will examine how the pattern of hurricanes in the Gulf of Mexico region will change by mid-century.

According to the Times-Picayune's Mark Schleifstein, the study will combine NCAR's powerful computer models and estimates of future greenhouse gas production to predict future hurricane activity. The models, which will help reconstruct past weather patterns in the Atlantic Ocean, Caribbean Sea and Gulf, will focus on the following three 10-year periods: 1995-2005, 2020-2030 and 2045-2055. The first results are expected to be available as early as next January, with the first fully fleshed-out assessment due by mid-2009.

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Rainfall and hurricane intensity likely to increase, though overall consequences remain uncertain
The project's goal is to inform the decisions of local governments, offshore drilling firms and other businesses likely to be put at risk by an increase in hurricanes. While many have linked the recent surge in hurricane intensity to the warming of sea surface waters, several reports, conducted by the U.S. Climate Change Science Program and Intergovernmental Panel on Climate Change (IPCC), have said that there is still much uncertainty about future trends -- though they conclude that rainfall and intensity will probably increase.

Its immediate benefits will be providing local officials and managers with a better understanding of hurricanes, which could help the energy industry mitigate the risk associated with its operations in the Gulf. In addition to examining the impact of climate change on hurricanes, the project will also look at how a rise in future GHG emissions will affect the regional climate -- and how the hurricanes themselves might affect it as well.

NCAR ready to deploy supercomputer models to get the job done
To do this, NCAR will use an approach called Nested Regional Climate Modeling (NRCM), which allows it to "nest" a version of its high-res weather model inside its lower-res global climate model. This lets it study specific weather patterns for a particular region while also incorporating the elements of the global climate. The research institution will use its latest supercomputer, IBM's Bluefire, to do the heavy number-crunching. Schleifstein has a nice description of the model design:

The new study starts with a coarser, global model -- meaning one in which data points for calculations are spaced many miles apart. Then, the researchers use a modeling technique called nesting, in which a smaller grid pattern is used within the larger grid to provide greater detail in selected areas.

The smallest pattern -- with grid points only about 2 1/2 miles apart -- will be laid across the Gulf of Mexico and westernmost Caribbean Sea, to capture the most detailed results about the intensity and frequency of hurricanes.

A second smaller grid pattern will lie over the western United States, where it will pick up information about frontal patterns that might affect hurricanes. But the data there also will help predict rainfall and snowfall patterns that will guide planners dealing with the potential for drought or flooding.

Via ::NSF: Future Risk of Hurricanes: The Role of Climate Change (press release)

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