From: "Glenn Meadows" 

Hmm....so global warming is a NATURAL thing?  We'd warm faster without
human intervention?  Methinks that it's possible that our contribution to
global warming might be an insignificant factor, and we might have actually
slowed it for a time?

--

Glenn M.
"Rich Gauszka"  wrote in message
news:427b7a5c{at}w3.nls.net...
> Clean air enhances global warming? Al Gore in shock at news? 
>
> http://www.nature.com/news/2005/050502/full/050502-8.html
>
> Our planet's air has cleared up in the past decade or two, allowing more
> sunshine to reach the ground, say two studies in Science this week.
>
> Reductions in industrial emissions in many countries, along with the use
> of particulate filters for car exhausts and smoke stacks, seem to have
> reduced the amount of dirt in the atmosphere and made the sky more
> transparent.
>
> That sounds like very good news. But the researchers say that more solar
> energy arriving on the ground will also make the surface warmer, and this
> may add to the problems of global warming. More sunlight will also have
> knock-on effects on cloud cover, winds, rainfall and air temperature that
> are difficult to predict.
>
> The results suggest that a downward trend in the amount of sunlight
> reaching the surface, which has been observed since measurements began in
> the late 1950s, is now over.
>
> The researchers argue that this trend, commonly called 'global dimming',
> reversed more than a decade ago, probably following the collapse of
> communist economies and the consequent decrease in industrial pollutants.
>
> The widespread brightening has remained unnoticed until now simply because
> there wasn't enough data for a statistically significant analysis, says
> Martin Wild, an atmospheric scientist at the Swiss Federal Institute of
> Technology in Zurich and an author on one of the reports.
>
> Sunny days
>
> Wild and his team looked at data on surface sunshine levels from hundreds
> of devices around the planet. They found that since the 1980s there has
> been a transition from decreasing to increasing solar radiation nearly
> everywhere, except in heavily polluted areas such as India and at
> scattered sites in Australia, Africa, and South America1.
>
> A second study, led by Rachel Pinker from the University of Maryland,
> College Park, found a similar trend by looking at satellite data, although
> their research suggests the extent of the brightening is smaller2. Unlike
> ground stations, satellites can sample the whole planet, including the
> oceans. However, satellite data are difficult to calibrate, and so are
> considered less accurate than measurements from the ground.
>
> Surprisingly, Wild's study shows a brightening trend in China, despite the
> fact that there is a booming, fossil-fuel-intensive industry in that
> country. Wild says he can only speculate that the use of clean-air
> technologies in China might be more widespread and efficient than has been
> thought.
>
> In contrast, India's vast brown clouds of smog, which result from
> wildfires and the use of fossil fuels, have reduced the sunlight reaching
> the ground.
>
> Researchers will now focus on working out the long-term effects of clearer
> air. One thing they do know is that black particulate matter in the air
> has been contributing a cooling effect to the ground. "It is clear that
> the greenhouse effect has been partly masked in the past by air
> pollution," says Andreas Macke, a meteorologist at the Leibniz Institute
> of Marine Sciences in Kiel, Germany.
>
>

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