I see the 'net is abuzz with the new discoveries about soot. But so far it seems that only a few environmentalists and bloggers have caught onto the news, and just a handful of pundits. Again the blogosphere is way ahead of the pack.
Perhaps it's not too puzzling that James Hansen of NASA GISS has known about soot's role in the Arctic since 2003. In earlier papers Hansen, et al, published, it had appeared that though soot was a major culprit in the Arctic ice loss, the net partial effect of total global AGW was only 25%. That left the other 75% to worry about, leading climatologists to recommend curtailing both CO2 & soot emissions. I don't think anyone in climatology - or in the opposition skeptic's corner - anticipated this past summer's (2007) discoveries of airborne soot's surprising heat-trapping characteristics.
Recap:
1. 90% of the Arctic, tundra & taiga net melt-offs are due to soot deposition (see my blog). Most of the soot may originate in Asia, but the expanding Russian oil fields also cast a pall of soot across the Arctic. The past century's Arctic ice loss represents 25% of total global AGW (see my blog).
2. 50% of atmospheric warming *within* brown clouds is due to soot's heat-trapping properties. This had heretofore been attributed soley to CO2 as it had been believed that soot was cooling agent (causing regional dimming) - by an equal margin of minus 50 percent (-50%). The science on soot has almost functionally reversed itself overnight w/ the role of soot as a heat-trapping particulate. (ibid).
3. 40% of atmospheric warming in the Pacific is caused by dispersed airborne soot (most of it originating in Asia). 75% of the soot airborne over the Western USA is still from Asia (e.g. China's soot may account for about 30% of extra forced warming in springtime Oregon). (ibid)
4. The bulk of airborne soot comes from coal-burning, diesel motors and biomass/wood fires. I might note that in 2001 the current president (anagrammatically, Herbage Glue Works) did instate new regulations to clean up off-road diesel soot emissions, a regulatory initiative long neglected by his ... erm ... predecessors. I might not take exception to anyone pointing out the irony that by pure happenstance that GW-B has done more to fight A-GW ... ;-)
Soot travels worldwide and is a problem worldwide, it just happens to be at its worst in the notorious Asian Brown Cloud and eastward across the Pacific. Were we to assume that soot dispersal is almost universally global, and fairly even (and at this point I don't know if anyone really knows for certain), we might take that net 40% heat-trapping role, apply it to the warmer & damper (not cooler & drier) latitudes where CO2's warming effects are lessened & soot's effects are most pronounced.
Back of the napkin calculation: 40% + 25% = 65% of all observed human-caused global warming might be due to soot. Too high a figure? OK, shave 15% off - 25% airborne soot heating instead of 40% - we're still looking @ 50% soot vs. 50% CO2. That's a lot of atmospheric greenhouse effect!
That 40% global average for soot might not be so far off the mark, however. There are major non-point source soot emissions in the subtropics and tropics with vast seasonal slash-and-burn forest fires from itinerant farmers in Yucatan, throughout Amazonia, Indonesia, Malaysia and Africa. The Yucatan burns can reduce visibility to less than 5 miles in locale as far as Austin, TX & beyond (I can tell you it looks like hell & is miserable - as bad as 1960's L.A.).
What's great about this news is this: Soot disperses within months *AND* once the dirtied Arctic ice falls into the sea, so there is great promise that the Arctic would recover as soon as Arctic sootfall sufficiently abated.
Records suggest there was a big Arctic melt-off during the late 19th & early 20th century that as late as the mid-1920's saw wide-open morraines of gravel & rock and major glacial recessions north of the Arctic circle. Recent studies in Greenland found those very soot deposition layers that diminished in the mid-1920's, establishing the link between the anecdotal accounts from the era to the actual deposition of soot (from wood-burning fires, etc.).
This does cast some doubt on the state of the art of climatology, that such a broad assumption that soot's effect of dimming the surface also suggested it was an atmospheric coolant. That the soot-coolant notion had stood unchallenged for so long, and that its newly discovered role is so absolutely contrary to the prior conventional wisdom, does suggest that there's more research to do w/ the other big atmospheric unknowns like aerosols, etc. Maybe score one for the milder skeptics? :-)
However, it does proffer win-win opportunities for everyone, industrialists & environmentalists alike. As Prof. Ramanathan of the Scripps Inst. for Oceanography points out, this could help us out of our conundrum. It gives nations and industrialists a phased alternative, it gives environmentalists a tangible gain & both parties a chance at good faith cooperation with each other.
Technically speaking, soot's not a greenhouse gas, nor is it an aerosol - it's a particulate. It's actually good to make this distinction for a few reasons. Soot disperses very quickly, within months, whereas gases like methane & CO2 persist for years (so the chronic problem w/ CO2 will still be there for continued study & solutions).
Soot-scrubbing tech is readily at hand, a worldwide initiative could start abating soot emissions tomorrow. There are also other side benefits such as mitigating smog and some heavy metals that may bind to soot.
And depending on what the gross heat-trapping role of soot is determined ... whether it's 40% or 65% of total global AGW, dealing with it readily may help us dodge a bullet in a very manageable way. Kyoto was a marginal pilot program at best, the EU carbon trading scheme is going to need a total restructuring after its carbon trading price crash earlier this year (2006-2007) and last week's Vienna climate meeting's recommendations were non-binding (and didn't make any kind of definite statement about soot...).
See also my blog:
http://leebert.newsvine.comI've contacted a handful of think tank fellows about this, explicated at depth, many are not aware of this yet. I'm trying to spread the word. Xithras, if you'd like to collaborate on this, please contact me. If you're interested in working w/ me on this I'll check my messages - I can't send private messages, I'm freshmeat on DU.
Best regards,
/leebert
(edited for grammar, clarification, additional commentary)