New study links rise in number of hurricanes to improved quality of air news
24 June 2013

The rise in the number of hurricanes could be a side effect of the global efforts to improve the quality of air, according to a new study.

The study by the UK's national weather service said ''anthropogenic aerosols'' - tiny airborne particles emitted by vehicles, factories and households - helped keep a lid on the number of tropical storms in the North Atlantic for most of the twentieth century.

However, the frequency of storms rose after moves to fight pollution led to ''sharp declines'' in aerosol levels from 1990, The Australian reported.

According to researchers, their findings corroborated 2012 research linking aerosols with hurricanes.

''Continued mitigation of aerosols may lead to further increases in tropical storm frequency,'' the report said.

''External factors, particularly anthropogenic aerosols, could be the dominant cause of historical tropical storm variability,'' said the report.

Airborne particles could cut the strength of storms by seeding clouds and encouraging rain, however, according to research, aerosols had also helped prevent hurricanes by reducing North Atlantic surface temperatures.

During the modelling, the researchers found that aerosols had been responsible for a 0.2 degree Celsius decline in average sea surface temperatures between about 1880 and 1980.

According to Johannes Quaas, a theoretical meteorologist at the University of Leipzig in Germany, scientists had been  ''uncertain'' about the effect of airborne particles on tropical storms.

 The journal Nature Geoscience has published the study.

Hurricanes, powerful rotating tropical storms affect the Atlantic, Gulf of Mexico and eastern Pacific; in other parts of the world similar storms known as typhoons or cyclones.

The storms form over warm ocean water and reach up to 600 miles across with spiralling winds reaching speeds of 200 mph. On an average around 90 tropical storms occur each year globally.

The North Atlantic has seen a clear rise in the frequency of tropical storms and hurricanes, increasing from an average of 10 per year between 1850 and 1990 to 15 per year between 1998 and 2007.

The number of storms powerful enough to be classed as hurricanes has risen from five per year to eight per year during the same periods.

Several studies had shown a global trend towards hurricanes and other cyclonic storms becoming stronger and more destructive, with the clearest evidence of growing storm intensity seen in the North Atlantic and Indian Ocean.

The possibility of a link between increased tropical  storm activity and global warming has been the subject of an ongoing scientific debate.

The Intergovernmental Panel on Climate Change (IPCC) said in 2007, that it was "more likely than not" that since the 1970s, humans had contributed to hurricane intensification.

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New study links rise in number of hurricanes to improved quality of air