Less Fog Explains Warming Europe, Study Says

Date: 19-Jan-09

Country: UK

Author: Michael Kahn

LONDON - Fewer foggy, misty and hazy days help explain why Europe's temperatures have risen so fast over the past 30 years, a finding that could help predict future climate change, researchers said on Sunday.

Clearer skies due to changing weather patterns and less air pollution have contributed on average to about 5 to 10 percent of the region's warmer temperatures during this period, said Geert Jan van Oldenborgh, a researcher at the Royal Netherlands Meteorological Institute.

"The temperatures in Europe have been going up twice as fast as climate models had predicted in the past decades. Less fog means more sunshine on the ground and hence higher temperatures," Van Oldenborgh, who worked on the study said in a telephone interview.

The U.N. Intergovernmental Panel on Climate Change, a group of hundreds of scientists, has predicted global temperature increases this century of 1.8 to 4 degrees Celsius.

Governments and researchers across the world are exploring ways to try to slow rising temperatures that experts say will bring heat waves, droughts, more powerful storms, species extinctions and higher sea levels.

In Europe, however, temperatures have been outpacing climate models and Van Oldenborgh and colleagues wanted to find out why.

They collected data from 342 weather stations at airports across Europe and measured the levels of fog, mist and haze going back to 1976.

The number of days with visibility less than 2 kilometers are half of what they were 30 years ago, falling to an average 10 days from 20 days, the researchers reported in the journal Nature Geoscience.

Changes in weather patterns and better air pollution policies play a role in the clearer skies but the researchers do not know how big an impact each contributes on its own, Van Oldenborgh said.

The warming trend due to less fog will ease, however, in the future because when it comes to air pollution governments can only make the skies so clean, he added.

"Climate is not simple and this is a new factor," Van Oldenborgh said.

"It doesn't explain everything but it explains a lot.

(Editing by Maggie Fox and Sophie Hares)

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