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Earth's air is clean but this may worsen the greenhouse effect
Air polution may be a good thing! I love comedies!
 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.
| Yeah. We were damned when we didn't. Now we're damned when we did. |
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.
| That means there wasn't grant money available, I'd guess... |
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 smaller. 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.
Posted by: Sobiesky 2005-05-06 |
