LONDON—Willis Group Holdings Ltd. has joined researchers in the United Kingdom and Japan in an effort to measure the impact of climate change on the frequency and severity of natural catastrophes using a Japanese supercomputer.

With guidance from Willis Research Network, a unit the broker created last September, researchers will use the NEC Earth Simulator computer in Yokohama, Japan, to develop catastrophe projections useful to international insurance and reinsurance markets.

The power of the Earth Simulator, with a sustained processing speed of 27 trillion operations per second, will allow much more detailed projections of changing weather patterns than have been possible on other systems, said Rowan Douglas, London-based chairman of Willis Research Network and executive director of Willis Re.

"The scale difference is an order of magnitude different from where we were before," he said.

The project "has the advantage of having the most resolution of any of the models available for climate study," said Christopher Landsea, science and operations officer for the National Oceanic and Atmospheric Administration's National Hurricane Center in Miami. Mr. Landsea is not involved with the Willis project.

Global climate models typically don't capture hurricanes well because the storms are too small—at, say, 100 miles in diameter—for those models to make their features recognizable, Mr. Landsea said. The finer resolution possible with the Earth Simulator should pick out those features more readily, he said.

The first results of the research are expected in about a year and will be publicly available in published academic papers, Mr. Douglas said. The data should be useful in its published form to insurers assessing their exposures, and may also be used in future updates of catastrophe modeling programs, Mr. Douglas said.

"We are right at the first stages of it," he said.

The Earth Simulator was built by the Japanese government in 2002 and is managed by the Japanese Agency for Marine-Earth Science and Technology. With 640 processor nodes, the computer occupies a space roughly equivalent to four tennis courts, Mr. Douglas said.

In 2005, academic and government researchers formed the U.K.-Japan Climate Collaboration, and began using the Earth Simulator to run a global climate model developed by the U.K. government's Hadley Centre for Climate Change. The Hadley Centre model, known as HadGEM, provided data for the Intergovernmental Panel on Climate Change's recent report concluding that human activity is causing global warming.

Now, Willis Research Network is working with these scientists and the University of Reading's Walker Institute for Climate System Research in Reading, England, to tailor the HadGem model to the needs of insurers and reinsurers.

The three-year research project aims to use the Earth Simulator to analyze the likely frequency and severity of hurricanes and typhoons, along with changes in rainfall patterns, under different climate change scenarios. The project will provide better data for catastrophe modeling programs and will improve seasonal forecasts and climate change projections, those involved say.

While the Earth Simulator models global climate patterns, its power and improved simulation techniques will allow researchers to model regional weather and extreme events such as hurricanes, according to Willis.

Insurers, in turn, will be able to use the data to prepare for the levels of catastrophe exposure that may come with climate change.

"We expect to give the market a much better view of likely events from realistic climate change scenarios," Mr. Douglas said.

Willis formed the Willis Research Network to collaborate with scientific institutions involved in studies of natural hazards and their impact. Partners in the network include seven U.K. universities.