Global warming is fueling stronger hurricanes according to a new Geophysical Research Letters study that revises that database of historic hurricanes.

Previously the hurricane database was considered inconsistent for measuring the record of tropical storms since there have been significant improvements in the technology to measure storms since recording-keeping began. Before the development of weather satellites, scientists relied on ship reports and sailor logs to record storms. The advent of weather satellites in the 1960s improved monitoring, but records from newer technology have never been squared with older data. The new study “normalizes” the hurricane record since 1983.

“The debate is not about scientific methods, but instead centers around the quality of hurricane data,” said lead author James Kossin, a research scientist at UW-Madison’s Cooperative Institute for Meteorological Satellite Studies. “So we thought, ‘Lets take the first step toward resolving this debate.'”

Warm ocean waters fuel hurricanes, and there was plenty of warm water for Katrina to build up strength once she crossed over Florida and moved into the Gulf of Mexico. This image depicts a 3-day average of actual sea surface temperatures (SSTs) for the Caribbean Sea and the Atlantic Ocean, from August 25-27, 2005. Every area in yellow, orange or red represents 82 degrees Fahrenheit or above. A hurricane needs SSTs at 82 degrees or warmer to strengthen. The data came from the Advanced Microwave Scanning Radiometer (AMSR-E) instrument on NASA’s Aqua satellite. The GOES satellite provided the cloud data for this image. Image Credit: NASA/SVS.

“This new dataset is unlike anything that’s been done before,” he continued. “It’s going to serve a purpose as being the only globally consistent dataset around. The caveat of course, is that it only goes back to 1983.”

Kossin and co-authors Daniel Vimont, a UW-Madison atmospheric scientist, Ken Knapp, a scientist at the NCDC, and Richard Murnane, a scientist at the Bermuda Institute of Ocean Sciences, used the new dataset to assess two controversial studies (published in Nature and Science) that argued climate change is causing more frequent and intense hurricanes.

The authors found that the conclusions hold for the Atlantic but not other parts of the world.

“The data says that the Atlantic has been trending upwards in hurricane intensity quite a bit, but the trends appear to be inflated or spurious everywhere else, meaning that we still can’t make any global statements,” said Kossin. “The average conditions in the Atlantic at any given time are just on the cusp of what it takes for a hurricane to form. So it might be that imposing only a small (man-made) change in conditions, creates a much better chance of having a hurricane.”

Hurricanes require temperatures of around 27 degrees Celsius (81 degrees Fahrenheit) to develop. Because the Atlantic Ocean is cooler than other areas where hurricanes (known as typhoons in the Western Pacific and cyclones elsewhere) form, it is more susceptible to small changes in ocean temperature say the researchers.

While the new research has normalized the satellite-based hurricane records, other scientists are working to develop alternative ways to measure historic hurricanes including tropical caves and tree rings

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This article used quotes and information from a University of Wisconsin-Madison news release