I cannot imagine how adding soot to the atmosphere would lead to cooling instead of warming.
On the use of sulfates, indeed there were problems as a result of deposition. The worst problems occurred when the sulfate was not lofted and so dispersed, as opposed to local, concentrated deposition. Sometimes this occurred well down some particular trajectories (such as UK to Scandinavia). The question is whether there might be a way, by selectively determining locations and the particular weather, to build up sulfate concentrations over dark oceans rather than over land and forests. Certainly there would still be (and likely are now) some adverse consequences, but one would seek to minimize those. Then the question is how these impacts would compare with the effects of the warming that is being alleviated--and how this would compare with the balance for other approaches and the costs and challenges of implementing the various approaches. Mike MacCracken On 12/23/08 4:31 AM, "Andrew Lockley" <[email protected]> wrote: > Thanks, I hope others with opinions about this and other categories > will put their views forward. > > I'm concerned by the use of sulphur in this way. It caused terrible > damage to the forests of Europe in the 70s and 80s. At this time it > was apparently difficult to establish exactly which sources were > causing the problem. How can we ensure that this does not happen > again? > > Furthermore, I understand that tropospheric soot is also very > significant, and that some have proposed using 'dirty burn' in ships > and aircraft to promote cooling. Smoke from rainforest fires in SE > Asia is apparently sufficient to promote regional cooling. Should > this go on the IN list? > > A > > 2008/12/23 Mike MacCracken <[email protected]>: >> Dear Andrew-- >> >> Although not done intentionally (well, in many cases we have chosen not to >> use the technology that would maximally limit emissions), we are already, >> quite fortunately, creating a significant cooling influence with >> tropospheric sulfate aerosols. While there are negative side effects, >> comparing those against the impacts this cooling presently alleviates >> (resulting from about the 0.5 C cooling influence) has not been done, but >> might not be clear-cut. >> >> In that there is no overwhelming negative influence of the tropospheric >> sulfate aerosols, one could well imagine increasing their amount, at least >> to generate additional sulfate aerosols in regions where ecological impacts >> are likely to be minimal. So, increasing tropospheric sulfur dioxide >> emissions from the elevated stacks of coal-fired power plants or by some >> other means of lofting the sulfur dioxide to above the boundary layer (where >> its lifetime is long enough to allow conversion to sulfate aerosol) would >> seem to be an option to be included in the IN category. Indeed, there may be >> adverse impacts in terms of deposition and human health, but it may well be >> possible to manage the emissions to that they occur only for trajectories >> that take the sulfates out over the oceans or to other locations where >> deposition would not be problematic. >> >> In fact, given the apparently increasing SO2 emissions from the new >> coal-fired power plants in China (as evidenced by the high sulfate levels >> shown in the figure in the IPCC WG I report), this approach to limiting >> warming may already be having some effect--indeed, maybe, as in the mid 20th >> century, sulfates may be what seems to be somewhat slowing the warming over >> the past decade. >> >> Mike MacCracken >> >> >> On 12/22/08 8:37 PM, "Andrew Lockley" <[email protected]> wrote: >> >>> >>> Can anyone else help me 'rank' the technologies? Just because people >>> talk about a tech lots doesn't mean it's actually any good! I'm >>> getting the impression that the following are basically in/out >>> >>> IN >>> Sea water spraying >>> Sulphur stratospheric seeding >>> Ocean fertilisation with iron/urea >>> White roofs (nice but not very effective) >>> >>> DON'T KNOW >>> Limestone powder into the sea >>> Fake plastic trees >>> Biochar >>> Removing HCl from oceans >>> >>> OUT >>> Nuclear bombs >>> Space mirrors >>> Shiny balloons >>> Sea albedo from litter/pykrete >>> Low level soot and sulphur burning >>> >>> This is obviously just a list based on my bar stool expertise. If >>> anyone with more knowledge could help that would be appreciated. Any >>> references to an objective ranking system that I can put in the wiki >>> would be appreciated. >>> >>> A >>> >>> >>> >> >> >> --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "geoengineering" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/geoengineering?hl=en -~----------~----~----~----~------~----~------~--~---
