African Press International (API)

Photo: NASA

Cyclone Nargis captured by the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite over the Bay of Bengal between India and Myanmar on May 2, 2008

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JOHANNESBURG,  – As the level of carbon dioxide increases in the atmosphere, we will probably see fewer but more intense storms, a group of the world’s top experts on tropical cyclones and climate change have concluded.

The update of the possible impact of climate change on tropical cyclones has been published in the March 2010 issue of the peer-reviewed journal, Nature Geoscience.

The Expert Team on Climate Change Impacts on Tropical Cyclones at the World Meteorological Organization (WMO) projects that these storms will intensify from 2 to 11 percent by 2100.

The study also projects decreases in the global average frequency of tropical cyclones by between 6 to 34 percent over the same period.

The wide range in the percentages reflects the large uncertainty that looms over predicting tropical cyclone activity in a changing climate, explained Thomas Knutson, the co-chair of the expert
team and the lead author of the study.

Hurricanes, cyclones and typhoons are tropical cyclones with a maximum sustained wind speed of more than 119km per hour near their centres.

The Expert Team noted in their last assessment, in 2006, that there was “substantial disagreement” between global and regional projections on the impact of climate change on tropical cyclone intensity.

Knutson said that while fewer tropical cyclones overall will be expected in the future, there was more that a 50 percent chance that the frequency of the most intense tropical cyclones, like the category four and five cyclones with a maximum sustained wind speed of more than 212 km per hour, will increase.

The frequency of the most intense tropical cyclones, like the category four and five cyclones with a maximum sustained wind speed of more than 212 km per hour, will increase

Cyclone Nargis, one the world’s deadliest storms, which killed more than 140,000 people and ruined countless lives and livelihoods in Myanmar in 2008 was a category four cyclone.

The development of better climate models that can predict changes in cyclone activity under projected climate scenarios has helped raise the confidence levels of the expert team.

“About 15 percent of the world’s tropical cyclones occur in the northern Indian Ocean, but because of high population densities along low-lying coastlines, the storms have caused nearly 80 percent of cyclone-related deaths around the world,” according to the US government’s National Aeronautics and Space Administration (NASA).

After Cyclone Nargis struck, a NASA team used three-dimensional satellite imagery and atmospheric profiles from the Atmospheric Infrared Sounder (AIRS) instrument aboard NASA’s Aqua satellite to see into the heart of the cyclone and plot its course, according to a news feature on their website.

NASA hopes the improved modelling made possible by the AIRS instrument will help forecast the path of cyclones and provide enough warning for people to be evacuated.

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