What's this? Global Dimming?

www.guardian.co.uk... Very fascinating story. Goodbye sunshine Each year less light reaches the surface of the Earth. No one is sure what's causing 'global dimming' - or what it means for the future. In fact most scientists have never heard of it. By David Adam Thursday December 18, 2003 The Guardian In 1985, a geography researcher called Atsumu Ohmura at the Swiss Federal Institute of Technology got the shock of his life. As part of his studies into climate and atmospheric radiation, Ohmura was checking levels of sunlight recorded around Europe when he made an astonishing discovery. It was too dark. Compared to similar measurements recorded by his predecessors in the 1960s, Ohmura's results suggested that levels of solar radiation striking the Earth's surface had declined by more than 10% in three decades. Sunshine, it seemed, was on the way out.

Nothing to worry about. It's balanced by the Earth losing it's orbit and "hurling" towards the sun...

www.abovetopsecret.com...

Interesting how this really hasn't made the mass media hasn't jumped on this like it has Global Warming.

With both of these occuring we could be further undermining the stability of the climate. At least it seems that perhaps the reductions in pollution over the last decade may have rectified this somewhat.

Must be all those aerosols the governments have been spraying to reduce global warming effects. Instead they increased atmospheric albedo so much that the climatic pendulum is now swinging the other way. These scientists and officials need a slap on the wrist, like when a mother takes her child into a store full of fragile items. DON'T TOUCH! YOU BREAK, YOU BUY!

Why haven't they investigated the obvious -- pollution?

When I take a jet around the country (or to other countries), I can *always* tell when I'm over the ocean or far away from cities by the way the brown smog in our atmosphere diminishes. It's very obvious on flights across the Pacific.

You still see some brownishness at lower levels, but it's nothing like the brown air you see flying into Los Angeles and other places.

I think that very very strong evidence can be made for "smog" being the cause.

Actually Byrd, I'm going to have to disagree that smog is responsible. However, I do agree that other pollutants have affected the atmosphere.

Smog is a relatively low lying phenomenon that only acts to increase warming by insulating a city or region by trapping radiant energy from the sun. On the flip side, sulfur dioxide (the molecule responsible for acid rain) increases the atmospheres ability to reflect the suns rays.

The same thing occurs after a volcano errupts as sulfur is released in copious quantities into the atmosphere. For example, the Filipino Mt. Pinatubo erruption in 1991 reduced global surface temperatures by as much as 4 degrees celcius in some regions in the Northern Hemisphere. Southern Hemisphere volcanoes are known to affect both hemisphere's surface temperatures while the effects of Northern Hemisphere volcano erruptions on surface temperature seem to be localized to the Northern Hemisphere. It is still unknown why the North recieves a "double whammy" in terms of being effected by both hemispheres volcanoes.

Points to consider:

1. A lot of the locations experiencing low light levels were in the Northern Hemisphere according to the article.

2. Europe is also plagued with acid rain and many sculptures/gargoyles dating back many centuries are becomming pock marked because of the sulfuric acid.

3. The Northern Hemisphere has more land mass than the Southern Hemisphere meaning greater chance of population sprawl and atmospheric pollution.

4. The Southern Hemisphere has more water than the North, consequently the South could be warmer as a result of retained heat by the water.

5. The Southern Hemisphere is actually closer to the sun on its Summer solstice than the North. Thus, radiant energy is less abundant in the north regardless of time of year leading to skewed approximations of what an "average" global temperature should be.

Following the chain of logic one can conclude that sulfur dioxide (S02) in the atmosphere must be primarily responsible for the decrease in temperature. And the scientists agree, sort of:

From SO's article:
The few experts who have studied the effect believe it's down to air pollution. Tiny particles of soot or chemical compounds like sulphates reflect sunlight and they also promote the formation of bigger, longer lasting clouds.

[Edited on 12-18-2003 by insite]

Man-made polution is very small. We just do not have the capacity to polute such a huge amount of space (being several times the size of the surface of the earth).

Volcanos on the other hand, create huge amounts of polutants (figures we could never hope to match).

No, man made polutants really only affect one thing, people.

We poisen ourselves.

Originally posted by KrazyJethro
No, man made polutants really only affect one thing, people.

Good one Jethro

[Edited on 12-18-2003 by insite]

I agree 100%, and here is why. There is less radiation because it is being absorbed by stuff in the air.

-P

Originally posted by Byrd
Why haven't they investigated the obvious -- pollution?

When I take a jet around the country (or to other countries), I can *always* tell when I'm over the ocean or far away from cities by the way the brown smog in our atmosphere diminishes. It's very obvious on flights across the Pacific.

You still see some brownishness at lower levels, but it's nothing like the brown air you see flying into Los Angeles and other places.

I think that very very strong evidence can be made for "smog" being the cause.

Originally posted by Byrd
Why haven't they investigated the obvious -- pollution?

Pollution makes the planet darker

But isn't this a good thing actually... Don't you think it may be the earth combating the lose of some of it ozone. It would seem to me that here we are worried that global warming is going to heat the earth and melt the polar caps, put wouldn't less light/radiation actually mean that the earth or something is trying to counteract the damage that is being done and is preventing less light in now. Could be that the oceans are warmer than they previously were and more water vapor is in the air. No disputing that water vapor/molecules reflect sunlight just as clouds darken the sky on a day that was sunny. I think this may be what is happening and with more water vapor in the mid atmosphere, the planet is protecting itself. Would explain the strange weather also...

I wonder if this has anything to do with everyone's perception that the sun is setting earlier.

www.abovetopsecret.com...

Hi SkepticOverloard. Sorry for double posting an article about the same thing! Guess it was too dim for me to see.

"It has nothing to do with changes in the amount of radiation arriving from the sun." This scares me. So really, the amount of polution that we are pumping into the atmosphere is the real culprit.

The relationship between Global Warming and Global Dimming needs a good study. Funny how it is tied to 'aerosols' and 'airborne particualtes' chemtrails anyone??? (lol I had to get that one in there