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Global Dimming
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Our Days Are Getting Darker - Literally

By James Donahue

There is another aspect of global warming that few are talking much about. It is called global dimming.

It seems that the more carbon and other chemical compounds we spew into the atmosphere the less light is getting through. Thus our days are getting dimmer and dimmer.

The change is so gradual that we don't notice it. But scientists note that there is a change going on. And it is beginning to have its effect on the world as well.

The change was first recorded in 1985 by Atsumu Ohmura, a researcher at the Swiss Federal Institute of Technology, who was recording levels of sunlight as part of a study of climate and atmospheric radiation. Ohmura discovered, to his shock, that the levels of solar radiation striking the Earth's surface between the 1960s and then had declined by more than 10 percent.

Ohmura was the first to document an effect that science now calls global dimming. It has now been established that over the past 50 years the average amount of sunlight reaching the ground has decline by about three percent a decade.

While it is going unnoticed because the change is gradual, the loss of light has implications for everything from solar power systems to plant photosynthesis. It also may be playing a major role in the climate changes we are experiencing. Yet for some strange reason the media has not picked up on this issue, nor have governmental reports dealing with Climate Change.

Graham Farquhar, climate scientist at the Australian National University, has picked up the ball since Ohmura's discovery. He has concluded that global dimming could explain one of the most puzzling mysteries of climate science. As the Earth warms, he noted that we might expect the rate of water evaporation to increase. But he says studies have shown that the rate of evaporation has diminished.

While there is less light, scientists are also alarmed because the rate of radiation and ultraviolet light now penetrating our dwindling ozone layer is not affected by the pollutants. Thus we are receiving less benefit from sunlight, while we are subjected to more harm.

Farquhar notes that global dimming also is having an effect on computer simulations designed to help meteorologists predict weather patterns and make accurate forecasts. The computer models are not designed to account for dimming sunlight.

Another burning question is how far will this solar dimming go and what are the future effects on our planet and our lives going to be?

This new threat is just one more important reason why we need to get our population and the polluting of our planet under control as quickly as possible. Failure to do so will only speed up the looming extinction of every species now in existence.

--January 2007