Global Dimming

I dug up some numbers for the effect that particulate pollution is having on the amount of sunlight reaching the Earth's surface. It is not trivial. I quote following piece from an article on View Post.

The effect was first spotted by Gerry Stanhill, an English scientist working in Israel. Comparing Israeli sunlight records from the 1950s with current ones, Stanhill was astonished to find a large fall in solar radiation. "There was a staggering 22% drop in the sunlight, and that really amazed me," he says.

Intrigued, he searched out records from all around the world, and found the same story almost everywhere he looked, with sunlight falling by 10% over the USA, nearly 30% in parts of the former Soviet Union, and even by 16% in parts of the British Isles. Although the effect varied greatly from place to place, overall the decline amounted to 1-2% globally per decade between the 1950s and the 1990s.

Gerry called the phenomenon global dimming, but his research, published in 2001, met with a skeptical response from other scientists. It was only recently, when his conclusions were confirmed by Australian scientists using a completely different method to estimate solar radiation, that climate scientists at last woke up to the reality of global dimming.

Dimming appears to be caused by air pollution. Burning coal, oil and wood, whether in cars, power stations or cooking fires, produces not only invisible carbon dioxide (the principal greenhouse gas responsible for global warming) but also tiny airborne particles of soot, ash, sulphur compounds and other pollutants.

The bottom line is that the radiation is absorbed into the atmosphere rather than the land and ocean. Although the comment is made that the portion reflected back into space is altered, that is pure speculation at this time. It is mostly absorbed by the particulate and associated water droplets and then reradiated as heat.

Although some have been quick to draw conclusions and wave around guesses masquerading as fact, the only thing we can be sure of is that the shift is significant and we surely are to blame for it.

And once again it is wise husbandry to end the causative practices. The atmosphere has turned out to be a far less forgiving sponge than we ever guessed for all our wastes. Just as a factory can destroy the ecology of a river, it appears that industrial man can amazingly disturb the global atmosphere in unwanted ways.

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