Global Dimming?

I first heard of this only a few months ago, I thought at first this was contradicting the global warming argument and didn't think to much about it. After watching the documentary below my powers of paranoia began tingling.

The basic premise is that the visible pollution we see from our exhaust, industry or even fires is filling the atmosphere with small particles of matter that when high in the atmosphere collect water molecules and reflect sunlight away from the earth.

So we have less sunlight hitting the earth while in contradiction the climate is warming. Is pollution holding back the bigger effects of GW? The problem is cleaning up the atmosphere will result in increased warming.
Or has this contributed to GW already due to efforts to stem the flow of pollution?

Is the so called chemtrail phenomena connected to this? are more particles being released into the atmosphere, to increase the effect? if so to what purpose? is it for combating GW or to seed secondary catastrophic effects in Africa and Asia by way of effecting rainfall. Some are blaming this for the massive drought followed by the tragic famine in Ethiopia in the 80s. (hence my paranoia about population reduction.)

So what do think? is this just another angle for the GW fear mongers or is this a real concern? Why aren't we hearing about this?

Sorry for all the questions but that's all I'm left with after watching this.

Global Dimming

I'll just add that I'm not a believer in man made GW, There are plently of threads here for that argument, this is not my intention here. Although that may be unavoidable because regardless of your opinion about GW I think there is no denying we are responsible for this.




[edit on 15-5-2007 by squiz]

Considering some of the threads on here I would have to agree and say global dimming has been going on for a long time.

Oh you mean light from the sun don't you?

As I understand it this phenomena was first noticed during some atmospheric observations taken in the days immediately after 9/11 when America's skies were plane free. Interesting stuff and one of the reasons I believe that when it comes to man's contribution to global warming CO2 is just a part of the equation... particle pollution is another.

Originally posted by grover
Interesting stuff and one of the reasons I believe that when it comes to man's contribution to global warming CO2 is just a part of the equation... particle pollution is another.

This was the contradiction I was talking about, technicaly particle pollution has a cooling effect.

Your right about the clear skies post 9/11. That is covered in the documentary.

Squizzy, yes, in places with problems with fine particulate pollution (especially China), this phenomenon is a big problem. In most developed countries which are using catalytic converters and other measures to take care of fine particulates, global warming is fully manifest (it's still manifest in places experiencing global dimming, just not so much so is my understanding) and global dimming is not an issue.

Well it seems that while particles do block light from getting in.... they work in conjuncture with CO2 to prevent heat from escaping. I was roundly ridiculed on one thread by a regular poster for connecting particle pollution and global warming... he was trying to use it to prove that I didn't know what I was talking about and all it did was highlight what an ass he is.

'Global Dimming' (daft name if you ask me) is the reason, for example, why during the 1960s and 70s carbon emissions were rising yet global temps were falling. Aerosols being emitted by industry were having a bigger cooling effect than the CO2 was with warming.

However, from the 80s onwards we started decreasing aerosol emissions - especially sulphur - because of pollution and acid rain concerns.

Also, whilst aerosols last only a few years in the atmosphere, CO2 lasts for decades.

Thus, since the 80s, aerosol emissions have fallen and those already in the atmosphere have rained out. But CO2 emissions have continued to rise, and the CO2 emitted in the past century is still around. So now it's the warming effect of the carbon that is winning.

Persistent contrails (misidentified as chemtrails by certain disinformationists) are not really part of this - like all high level clouds, they have a net warming effect, adding to that of CO2.

Of course, there are also other factors behind climate change, some natural, some - deforestation for example - very much down to us. Deforestation is thought by some to be a major factor in changes in rainfall distribution.

Thanks for the replies people, some good points raised. I agree with most of the comments. I'm not to sure about particle pollution trapping heat though, this would refute the studies done in the days following 9/11, with the planes down and no contrails filling the skies the temperature did rise.

Historical accounts of large volcanoe erruptions have shown that the reflection of sunlight had a bigger effect in cooling the planet rather than trapping the heat. As stated in the documentary many smaller particles reflect better than fewer larger particles.

As I said this is new to me, I've never heard this being brought up in GW debate before, but it seems it plays a major role in whats happenning to the climate.