Political Crossfire Forums

[bob.appleyard]

Okay, so cleaner emissions have reduced the number of aerosols in the atmosphere, which has meant that less sunlight is being reflected out into space as 20 or 30 years ago.

So some bright spakr has come up with a plan... stick some aerosos in there, with massive cannons!!!

Yes, it's nuts, and no, it probably won't work. But the chap who suggested it is a respected atmospheric scientist, so go figure.

Quote: Crutzen is, as you would expect, a brilliant man. He was one of the atmospheric chemists who worked out how high-level ozone is formed and destroyed. He knows more than almost anyone about the impacts of pollutants in the atmosphere. This is what makes his omission so odd.

. . .

He suggests we use either giant guns or balloons to inject sulphur into the stratosphere, 10 kilometres or more above the surface of the earth. Sulphur dioxide at that height turns into tiny particles – or aerosols – of sulphate. These reflect sunlight back into space, counteracting the warming caused by manmade climate change.

. . .

Crutzen recognises that there are problems. The sulphate particles would slightly reduce the thickness of the ozone layer. They would cause some whitening of the sky. Most dangerously, his scheme could be used by governments to help justify their failure to cut carbon emissions: if the atmosphere could one day be fixed by some heavy artillery and a few technicians, why bother to impose unpopular policies?

His paper has already caused plenty of controversy. Other scientists have pointed out that even if rising carbon dioxide levels did not cause global warming, they would still be an ecological disaster(3). For example, one study shows that as the gas dissolves in seawater, by 2050 the oceans could become too acid for shells to form, obliterating much of the plankton on which the marine ecosystem depends(4). In Crutzen’s scheme, the carbon dioxide levels are not diminished. It would also be necessary to keep firing sulphur into the sky for hundreds of years(5). The scheme would be extremely expensive, so it is hard to imagine that governments would sustain it through all the economic and political crises likely to take place in that time. But what I find puzzling is this: that by far the most damaging impact of sulphate pollution hasn’t even been mentioned – by him or, as far as I can discover, any of his critics.

In 2002, the Journal of Climate published an astonishing proposition: that the great droughts which had devastated the Sahel region of Africa had been caused in part by sulphate pollution in Europe and North America. Our smoke, the paper suggested, was partly responsible for the famines which killed hundreds of thousands of people in the 1970s and 1980s(6).

By reducing the size of the droplets in clouds, thereby making them more reflective, the sulphate particles lowered the temperature of the sea’s surface in the northern hemisphere. The result was to shift the Intertropical Convergence Zone southwards. This zone is an area close to the equator in which moist air rises and condenses into rain. The Sahel, which covers countries such as Ethiopia, Sudan, Chad, Niger, Burkina Faso and Senegal, is at the northern limits of the zone. As the rain belt was pushed south, those countries dried up. As a result of the clean air acts, between 1970 and 1996 sulphur emissions in the US fell by 39%(7). This appears to have helped the North Atlantic to warm, allowing the rains to return to the Sahel in the 1990s.

Since then, several studies – published in the Proceedings of the National Academy of Sciences, Geophysical Research Letters and the Journal of Geophysical Research – have confirmed these findings(8,9,10). They show that the 40% reduction in rainfall in the Sahel – which has “few if any parallels in the 20th century record anywhere on Earth” – is explicable only when natural variations are assisted by sulphate aerosols. We killed those people.

I cannot say whether or not Crutzen’s scheme would have a similar outcome. It is true that he proposes to use less sulphur than the industrialised nations pumped into the atmosphere, but does this matter if the reflective effect is just as great? Another paper I have read lists seven indirect impacts of aerosols on the climate system(11). Which, if any, will be dominant? What will their effects on rainfall be? Crutzen suggests that in order to keep the particles airborne for as long as possible they should be released “near the tropical upward branch of the stratospheric circulation system”(12). Does this mean that they will not be evenly distributed around the world? If so, will they shift weather systems around as our uneven patterns of pollution have done? I don’t know the answers, but I am staggered by the fact that the questions are not even being asked.

http://www.monbiot.com/archives/2006/08/29/no-quick-fix/

What do you chaps think? Is this an accurate criticism, or is it a good idea? You know what I think about it.

[ChuckBerry]

I don't think you should solve a man-made problem (if you believe global warming is caused by human activities) by further tinkering with the environment. This reminds me of the Yellow Stone article posted elsewhere on this site; government interference in national park management has caused greater problems than they have solved. If a return to a natural state is desired, then simply seek to reduce human pollution and let nature heal itself. Of course, there is the hysterical contingent that believe that we are already too far gone and runaway global warming is coming even if we stop all activities that contribute to globabl warming. For them, this scheme may make sense.

Not to me though. I don't believe that humans are contributing to global warming on a meaningful scale, and to attempt to reverse global warming will certainly cause unintended consequences. Think globally, act locally, and ONLY locally.

[toddytodd]

CCD wrote: I don't think you should solve a man-made problem (if you believe global warming is caused by human activities) by further tinkering with the environment. This reminds me of the Yellow Stone article posted elsewhere on this site; government interference in national park management has caused greater problems than they have solved. If a return to a natural state is desired, then simply seek to reduce human pollution and let nature heal itself. Of course, there is the hysterical contingent that believe that we are already too far gone and runaway global warming is coming even if we stop all activities that contribute to globabl warming. For them, this scheme may make sense.

Not to me though. I don't believe that humans are contributing to global warming on a meaningful scale, and to attempt to reverse global warming will certainly cause unintended consequences. Think globally, act locally, and ONLY locally.
Quote: If a return to a natural state is desired, then simply seek to reduce human pollution and let nature heal itself. Very well said