NASA and Global Warming: a New Study

A new NASA study has found that sunlight blocked by dust, pollution and aerosol particles appears to have lost ground. This finding, published in the journal Science, may lead to an improved understanding of the recent climate change on the earth. In a related study published last week, Scientists have found that "opposing forces of global warming and the cooling by the use of aeorsol-induced global dimming can actually occur at the same time.

The study uses the longest uninterrupted sattelite record of aerosols in the lower atmosphere, which since the 1990's could have given an extra push to the rise of the global temperatures;

"When more sunlight can get throught the atmosphere and warm Earth's surface, you're going to have an effect on climate and temperature", said Author Michael Mishchenko of NASA'S Goddard Institute for Space Studies (GISS), New York. "Knowing what aerosols are doing globally gives us that important missing piece of the big picture of the forces at work on climate."

The GISS reseach team conducted one of the most comprehensive experiment to date using computer simulations of the Earth's 20th-century climate to investigate the dimming trend. The combined results from nine state-of-the-art climate models, including three from GISS, showed that due to increasing greenhouse gases and aerosols, the planet warmed at the same time that direct solar radiation reaching the surface decreased. The dimming in the simulations closely matched actual measurements of sunlight declines recorded from the 1960's to the 1990's.

The combined effect of global dimming and warming may account for why one of the major impacts of a warmer climate - the spinning-up of the water cycle of evaporation, more cloud formation and more rainfall - has not yet been observed. "Less sunlight reaching the surface counteracts the effect of warmer air temperatures, so evaporation does not change very much," said Gavin Schmidt of GISS, a co-author of the paper. A major complicating factor is that aerosols are not uniformly distributed across the world and come from many different sources, some natural and some produced by humans.

This report has shown the important counter-balance to the Earth's warming by greenhouse gases however, finding out whether the recent rise and falls of aerosols is due to human activity or by natural changes will have to wait until the planned launch of NASA'S glory mission in 2008. With the importance of this find and the rapid rate of global warming surely NASA should push forward the 2008 glory mission immediately.