Global Dimming, Less Light Reaching Us

  • Thread starter Atrayo
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Hello Everyone,

If global warming wasn't enough, we now have "global dimming" to add to the equation. Although i get a funky feeling in the pit of my stomach both global warming and global dimming are inter-connected. :grumpy:

Here's a http://www.guardian.co.uk/life/feature/story/0%2C13026%2C1108853%2C00.html [Broken] at the British media outlet of the Guardian. (article dated December 2003)

But Farquhar had realised that the idea of global dimming could explain one of the most puzzling mysteries of climate science. As the Earth warms, you would expect the rate at which water evaporates to increase. But in fact, study after study using metal pans filled with water has shown that the rate of evaporation has gone down in recent years. When Farquhar compared evaporation data with the global dimming records he got a perfect match. The reduced evaporation was down to less sunlight shining on the water surface. And while Stanhill and Cohen's 2001 report appeared in a relatively obscure agricultural journal, Farquhar and his colleague Michael Roderick published their solution to the evaporation paradox in the high-profile American magazine Science. Almost 20 years after it was first noticed, global dimming was finally in the mainstream. "I think over the past couple of years it's become clear that the solar irradiance at the Earth's surface has decreased," says Jim Hansen, a leading climate modeller with Nasa's Goddard Institute for Space Studies in New York.
More importantly, what impact could global dimming have? If the effect continues then it's certainly bad news for solar power, as darker, cloudier skies will reduce its meagre efficiency still further. The effect on photosynthesis, and so on plant and tree growth, is more complicated and will probably be different in various parts of the world. In equatorial regions and parts of the southern hemisphere regularly flooded with light, photosynthesis is likely to be limited by carbon dioxide or water, not sunshine, and light levels would have to fall much further to force a change. In fact, in some cases photosynthesis could paradoxically increase slightly with global dimming as the broken, diffuse light that emerges from clouds can penetrate deep into forest canopies more easily than direct beams of sunlight from a clear blue sky.

But in the cloudy parts of the northern hemisphere, like Britain, it's a different story and if you grow tomatoes in a greenhouse you could be seeing the effects of global dimming already. "In the northern climate everything becomes light limiting and a reduction in solar radiation becomes a reduction in productivity," Cohen says. "In greenhouses in Holland, the rule of thumb is that a 1% decrease in solar radiation equals a 1% drop in productivity. Because they're light limited they're always very busy cleaning the tops of their greenhouses."
They've stated that it's mostly soot/dust from air pollution to have the most consisent effect on sunlight penetrating through the Earth's atmosphere. There can be also other factors, such as major volanic eruptions. Perhaps what Saddam did to the environment in the first Gulf War of 1991. Lighting up all those oil drills like flares. Perhaps even the decades ago atomic/nuclear bomb testing above the ground.

This kinda reminds me of one of those "Highlander" movies with Christorpher Lambert & Sean Connery set in a futuristic Earth. Where a technology to protect the Earth from a fully depleted ozone actually turns the world to complete darkness in a few decades. Hmm. :uhh:

The good news is i think the article mentions this:

O hmura says that satellite images of clouds seem to suggest that the skies have become slightly clearer since the start of the 1990s, and this has been accompanied by a sharp upturn in temperature. Both of these facts could indicate that global dimming has waned, and this would seem to tie in with the general reduction in air pollution caused by the scaling down of heavy industry across parts of the world in recent years. Just last month, Helen Power, a climate scientist at the University of South Carolina published one of the few analyses of up-to-date data for the 1990s and found that global dimming over Germany seemed to be easing. "But that's just one study and it's impossible to say anything about long-term trends from one study," she cautions.
 
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  • #2
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lol

Yeah it is now so dim that I don't even need to use my sun glasses. JK :rofl: .

Depleted Ozone? Do you even know how it is created?

1% decrease in light yields 1% decrease in productivity? Wow that means that all those people with night jobs get nothing done.

Metal pans filled with water, in what one city? one building? That does not sound scientific.

Atrayo, This is just alarmist pap. Do not get taken in by it.
 

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