The Irony Of Global Dimming

[The Eagle]

Hi all

How interesting is the theory of GD, the process where by pollutents block out sunlight. I think everyone agrees Global Warming exists, only whether it is man-made or not is up for debate. However it is very ironic that the process which, some say, leads to Global Warming, i.e the burning of fossil fuels also leads to Global Dimming which apparently is actually keeping the Earth cool!!!! What a funny world we live in

Edited November 9, 2005 by Darkman

[Typhoon John]

There's a Horizon on Global Dimming, was fairly interesting. Perhaps we should pump a load of dust into the atmosphere for a few years to get the winter we really want.

[The Eagle]

There's a Horizon on Global Dimming, was fairly interesting. Perhaps we should pump a load of dust into the atmosphere for a few years to get the winter we really want.

Hi fozi, i actually saw that progam, a bit of scaremongering toward the end but nonetheless interesting. It really is a catch 22 situation

[Guest Mike W]

Global Dimming is not happening anymore, it was referring to high amounts of SO2/Sulphur Dioxide emmisions that we used to pump out up into the amotsphere along with the CO2 before we decided to only sink the SO2 which causes coastal erosion because they use limestone from Dover Cliffs to sink the SO2, becasue their sinking something that cools they are leaving the CO2 which warms. So ever since that we have a situation were SO2 emmisons are almost non-existent and CO2 emmisons are very high causing a brightening and UV increases which casues warming aswell as CO2 warming, not the cleverest idea of the Goverment. If you ask me they should be only emmiting SO2 from tall chimmney stacks and sinking CO2 only, thus casuing a warming, that and switching to Nuclear and Hydrogen fuel,mixed with SO2 to limit the explosive effect of Hydrogen. But they stupidly won't do that. In fact it is well known that the main reason for the 62/63 winter many other famous winters was high amounts of Sulphur Dioxide causing big reduction of incoming radiation, becasue their was high amount of sunspots and hurricane activity which would have otherwise casued a mild winter, but he SO2 caused cold winter and on the same month that 62/63 winter started they had the last pea-souper in London, just look at the graphs availible on the net, you will notce that as SO2 levels have gone right done, CO2 levels have shot right up. Bring back mass SO2 emmisions using loads of tall-chimmney stacks, preferbly away from heavyly populated areas. If Blair and Bush are desperate enough for cooling they would do this.

[su rui ke]

Bring back mass SO2 emmisions using loads of tall-chimmney stacks, preferbly away from heavyly populated areas. If Blair and Bush are desperate enough for cooling they would do this.

Not sure 'bring back acid rain' would be a vote-winner though.

[Summer of 95]

I have my own theory about Global Dimming and how it affected the climate of 20th Century Britain.

IMO aircraft pollution at the tropopause and just below is one of the main culprits: Horizon mentioned a bit about this but seemed to think it's a more recent phenomenon than it really is. After the cold winters of the 1890s (the last gasp of the LIA I think) Britain warmed fast, especially in winter. For the first 40 years of C20 not one month had a subzero CET (it's only 19 years since the last one at present) and some winter months were of the kind that would raise eyebrows even among today's GW-conscious observers with their extreme mildness (eg Feb 1903, Jan 1916, Feb 1923, Dec 1934).

Car traffic and oil burning had steadily increased during this time, sowing the first seeds of dimming. However as the aircraft factor had not yet appeared, warming from greenhouse gases had the upper hand. Until World War 2 when suddenly vast numbers of polluting vehicles got into the upper air for the first time. Cue a start to dimming proper. and an immediate reversal to the warming. Cold winters in the 40s by the bucketload. From 1940-1970, coinciding with the cold period, air and road traffic increased many fold and industry continued to belch out other dimming chemicals. Then in the early 1970s suddenly we had an oil crisis. Less car and aircraft pollution for a while. And a run of incredibly mild winters followed by the hot 75/6 summers. Warming moves ahead on points again. Late 70s-late 80s: Oil crisis over. Air travel booms. New life breathed into dimming. A few more 1940-70 style winters.

Then in the late 80s the catalytic converter, and possibly green petrol too, eliminated the dimming chemicals from cars while they continued to belch out the warming ones. Aircraft continued to flourish, however the increasing contrails did not eliminate the warming having lost their cohorts from the ground polluters, but instead did the job they do best more so than ever- namely lowering the daily, monthly and annual temperature range. We haven't had much cold weather since.....

[Guest Mike W]

As I mentioned earlier it wasn't so much SO2 from cars that did the main cooling, it was factory's with their chimmney stacks and later tall chimmney stacks, but around the mid to late 80's they decide to stupidly concentrate first on sinking all the So2 they could while still belching out the greenhouse gas warming pollutants, CO2 and other such warming gases, end result boring years with little or no variation whatsoever and no chane of a snowy cold or severe winter, something which has increased especially post 1996. Acid rain is bad aswell as emphasima,but you have ask how desperate are you for a quick fix cooling solution, i.e return to our mass SO2 emmiting ways while at the same time sinking and surpression of CO2, which would cause a marked decreese in tempretures, just as temporary stop gap while new clean technologies become more availible and widespread, anyway SO2 mixed with Hydrogen would help lessen the explosive element in Hydrogen aparently according to chemical experts. If things are really bad and the warming increases like it is, it may come down to a quick fix and use cooling pollutents like SO2 unfotunately in order to stem the warming and induce cooling, even though I'm not massivley keen on the idea, but if the negatives of going into Iraq didn't stop Blair I don't see how SO2 emmiting will way to heavily on his mind. I think when CO2 levels have been cut back to 280ppm then we can satrt cutting back So2 emmisions because CO2 stays longer than SO2.

[Guest Mike W]

Don't get me wrong by the way I do not personally advocate emmiting vast amounts SO2, I was just saying that if our goverment send loads of people to get snipered to death day in day out to get more Oil supply's then they wouldn't think twice about emmiting loads of cooling pollutants that cause load of acid rain and crop failures aswell as emphasima, I personally would not condone this as aI think going towards the Hydrogen, Bio-fuel using manure [not Oil seed or trees, unless fast growing] aswell as Nuclear with wind, solar and water and wehere possible geo-thermal is the best solution.

[BLAST FROM THE PAST]

As I mentioned earlier it wasn't so much SO2 from cars that did the main cooling, it was factory's with their chimmney stacks and later tall chimmney stacks, but around the mid to late 80's they decide to stupidly concentrate first on sinking all the So2 they could while still belching out the greenhouse gas warming pollutants, CO2 and other such warming gases, end result boring years with little or no variation whatsoever and no chane of a snowy cold or severe winter, something which has increased especially post 1996.

All this is of course assuming that CO2 is causation and not consequence of warming. That has not been proved...remember last ice age had CO2 concentrations much, much higher than now.

Also it was my belief that global dimming was as a result of more sun energy being absorbed by Earth and less reflected? This according to NASA satellites has recently reversed.

BFTP

[Guest Mike W]

other way round i think, global dimming was caused by us reflecting more of the sun's energy not absorbing, sun's energy refelcted by SO2, and as a result of sinking SO2 whch is well known to help lessen the explosive nature of petroland deisel aswell as hydrogen, we now have rubbish winter after rubbish winter and hot year after hot, along with above average month after above average month, no variation. Still it was always a bad pollutant, not now though, cause it's virtually non-existent.

[jennyberki]

Was it that same Horizon programme that checked pan evaporation rates, and discovered that on the three days in recent history when there were no aircraft airborne (9th - 12th September 2001), the evaporation rates hugely increased? Therefore suggesting that air pollution (from aircraft anyway) is actually acting as a braking mechanism on GW, reducing the amount of heat reaching the earth's surface?

[Summer of 95]

Was it that same Horizon programme that checked pan evaporation rates, and discovered that on the three days in recent history when there were no aircraft airborne (9th - 12th September 2001), the evaporation rates hugely increased? Therefore suggesting that air pollution (from aircraft anyway) is actually acting as a braking mechanism on GW, reducing the amount of heat reaching the earth's surface?

Yes and no. What that study showed was that the diurnal temperature range over the USA increased dramatically, in the busiest air corridors by 3C or more, in the three days without air traffic.

http://www.wired.com/news/technology/0,1282,52512,00.html

[SNOW-MAN2006]

Hi all

How interesting is the theory of GD, the process where by pollutents block out sunlight. I think everyone agrees Global Warming exists, only whether it is man-made or not is up for debate. However it is very ironic that the process which, some say, leads to Global Warming, i.e the burning of fossil fuels also leads to Global Dimming which apparently is actually keeping the Earth cool!!!! What a funny world we live in

i dont think 'global warming' is the right terms. i agree the summers are getting warmer but i think that if the heat can get perfectly well through the atmosphere so it must be able to get back out just as easily. climate is changing but how long till the next ice age and we become cold again???

global dimming is very fascinating. it is keeping us cool and without it we could get warmer. but that may be a reason why we may be getting warmer. we are using less fuels and recycling more so therefore less gas/emmisions are being let into the air. so 30 years ago we didnt care about gw and therefore we had cold winters. now the amount of polluted air is decreasing meaning more sunlight getting through which then alternativly means more heat.

its just a theory and there are many more

*sm06*

[The Eagle]

i dont think 'global warming' is the right terms. i agree the summers are getting warmer but i think that if the heat can get perfectly well through the atmosphere so it must be able to get back out just as easily. climate is changing but how long till the next ice age and we become cold again???

global dimming is very fascinating. it is keeping us cool and without it we could get warmer. but that may be a reason why we may be getting warmer. we are using less fuels and recycling more so therefore less gas/emmisions are being let into the air. so 30 years ago we didnt care about gw and therefore we had cold winters. now the amount of polluted air is decreasing meaning more sunlight getting through which then alternativly means more heat.

its just a theory and there are many more

*sm06*

Yes GW is a theory yet to be backed up by credible evidence