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NeedToUseYou -> RE: Global Dimming (4/20/2006 12:24:42 AM)
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I saw or hmmm, downloaded it a while back I think I still have it, don't have cable anymore.
It's pretty compelling evidence really, it actually explains alot of the reasons global warming hasn't become apparent thus far.
The premise is that the particle pollution has caused less sunlight to reach the surface of the earth. This is documented worldwide, and isn't scientific theory. They were able to prove this using pan evaporation rates. It's pretty basic really, it's just how much water evaporates from a pan in a day. This has been tracked for decades, today less water evaporates from the pan than it had in the 60's, which implies there is less energy being transferred to the water. That's the first evidence.
Second, Scientist in the US, russia, Israel, just the ones I remember from the show. Have recorded and measured sunlight intensity periodicly over the last 50 or so years. They do this in order to plan irrigation projects as a means to predict water needed etc... Going back to the measurements in the 50's -60's there is about a 10% reduction in overall sunlight reaching the surface. This is also the exact amount of sunlight reduction that would account for the evaporation reduction in the pan evaportation rate. So two long-term scientifc measurements, spread among several countries around the world show the same data. Third after 9/11 when the planes were grounded it was the first time most air traffic was shut down and just those particles being removed from the equation raised the average temperature range for the day a few degrees compared to comparable conditions previous years.
Why is this caused. Well, it turns out that particles in pollution like smog and jet engine emissions etc.. once inside clouds cause the clouds to become more reflective, because they cause the natural formation of the rain drops to become much larger than if it naturally occurred. Usually rain drops begin by forming around dust or pollen. When water bonds with the pollution particles the drops tend to get larger. Overall effect is since it takes longer for water droplets to drop from the clouds, there are more clouds, and clouds reflect light back into space.
So the conclusion is that the Global dimming effect has been offsetting the Global warming effect to a large degree. It's pretty conclusive beyond any other documentary or evidence I've seen anyway. The show also goes into how the Amazon rain forest also has been acting as a Carbon reserve, if you measure the Carbon based gases entering the rain forest versus the air exiting. The rainforest is actually holding on to way more carbon than it releases due to vegetation dying and decomposing. In total the rainforest is absorbing 50 percent of excess carbon based gas production we are releasing. obviously the rain forest can't become denser and denser forever. Once the rain forest reaches it's capacity to absorb more carbon(become more dense). Then they speculate that it will be a dramatic shift in climate as twice as much carbon based gases will remain in the air. Adding that to the fact that we are cutting down the rainforest, it doesn't paint a pretty picture.
So, the conclusion is two factors are suppressing the effects of Global warming. 1 global dimming. 2. The fact that the rainforest is absorbing way more carbon based gases than previously thought. The rainforest will reach it's limit within the next 50 years, once that happens a spike should occur in global temps, raising the temp of the frozen depths of the ocean just a couple of degrees and releasing huge deposits of methane gas. These gases are the worst green house gases raising temps further. Once that happens, you can't stop it.
I thought the whole green house debate was pretty much crap before these explanation actually backed by real data. However, seeing the data and explanations, and the reason for the suppression of temps. It is really concerning me now. Not much we can do except abandon fossil fuels immediately and protect the rain forest which isn't going to happen anytime soon. The timeline for this to occur is within most of our lifetimes to so I guess we'll know if it's bullshit or not.
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