Can cleaner air lead to more hurricanes?

Global efforts to improve the quality of air could be resulting in more hurricanes as a side-effect, according to a new study.
"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, according to the study by the UK's national weather service.
However, the frequency of storms increased after moves to fight pollution led to "sharp declines" in aerosol levels from 1990, 'The Australian' reported.
Researchers say their findings corroborate 2012 research which linked 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 can reduce the strength of storms by seeding clouds and encouraging rain. But the research found that aerosols had also helped prevent hurricanes by reducing North Atlantic surface temperatures.
During the modelling, the researchers found that aerosols were responsible for a 0.2 degree Celsius decline in average sea surface temperatures between about 1880 and 1980.
Scientists had been "uncertain" about the effect of airborne particles on tropical storms, said Johannes Quaas, a theoretical meteorologist at the University of Leipzig in Germany.

Previous research has predicted greenhouse emissions will reduce Atlantic hurricane activity, partly because atmospheric temperatures are likely to rise faster than sea surface temperatures, and partly because of increased wind speed variability at different altitudes.
The study was published in the journal Nature Geoscience.