A satellite image of pollution haze over Eastern China captured in February 2004. The haze, consisting of a major fraction of soot and sulfate aerosols, was created from coal and wood burning and persisted throughout the winter season.
Credit: NASA MODIS
WASHINGTON: Pollution from Asia is helping generate stronger storms over the North Pacific, according to new research.
Changes in the track followed by storms in the North Pacific could have a knock-on impact on weather across the Northern Hemisphere. This is the first time researchers have detected a direct effect of pollution on clouds.
Studies have previously hinted that global warming could be increasing the ferocity of hurricanes, but the new finding adds to the evidence that man is having a profound influence on Earth's weather systems as a whole.
The research team, led by Renyi Zhang of Texas A&M University, in College Station, came to their conclusions by studying pollution and cloud patterns in the region between 1984 and 2005.
Satellite measurements have shown an increase in tiny particles generated from coal burning in China and India in recent decades - largely soot and sulfate from burgeoning industry. Zhang's team conclude that increasing particles cause a chemical reaction have enhanced cloud updraft to generate more intense thunderstorms.
Comparing 1984 to 1994 with 1994 to 2005 they found an increase of 20 to 50 per cent in 'deep convective clouds' - typified by several kilometres deep cumulonimbus clouds that can create powerful storms.
They report their findings today in the U.S. journal Proceedings of the National Academy of Sciences.
"The intensified storms over the Pacific in winter are climatically significant," the researchers wrote. The growing intensity of the track "can also impact the global general circulation."
The Pacific storm track, they noted, plays a critical role in global atmospheric circulation - and altering this weather pattern could have a significant impact on the climate. A particular threat, they added, is the potential for increased warming of polar regions.
As pollution from Asia increases with development, the problem may be further exacerbated.
In more positive climate news, another report in the same issue of PNAS reports that - in addition to protecting the ozone layer - the ban on ozone-depleting chemicals has slowed the rate of global warming.
The Montreal Protocol, signed in 1987, led to a reduction in the release of these chemicals into the atmosphere. The ban was an effort to preserve the ozone layer that screens out many of the Sun's damaging rays.
However, those same chemicals are also potent contributors to the greenhouse effect, and their reduction has resulted in a slowdown in global warming.
The savings in trapped heat are equivalent to about 10 years of growth in carbon dioxide concentrations, according to a team led by Guus J. M. Velders of the Netherlands Environmental Assessment Agency in Bilthoven.
