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http://www.cleanmpg.com/photos/data/2/AmericanFlag.jpg Black carbon may be 18% of AGW....fortunately it last a few months - not centuries (http://www.time.com/time/health/article/0,8599,1938379,00.html)

http://www.cleanmpg.com/photos/data/501/co2.jpgBrian Walsh - TIME (http://www.time.com) - Nov 13, 2009

Black carbon is the sooty stuff from coal, biomass, and diesel --Ed.

That soupy brown air is the result of so-called black carbon expelled into the atmosphere in and around the Indian capital, from the burning of biomass for cookstoves and of black coal for electricity, and the incomplete combustion in the old diesel engines that propel most of the cars and trucks in the city. Breathing here isn't all that good for you — there's a reason the city is home to the "Delhi cough" — and now scientists are discovering that the sooty air isn't good for the climate either. According to some estimates, black carbon may be responsible for as much as 18% of the planet's warming, making it the No. 2 contributor to climate change after carbon dioxide, which accounts for 40%. "The world could think that we just cut CO2 and the problem is solved and we all go home, but it's not," says Veerabhadran Ramanathan, a climatologist from the Scripps Institution of Oceanography and an expert on black carbon. "That's my nightmare."... http://www.time.com/time/health/article/0,8599,1938379,00.html

I thought we were being told not long ago that PM is responsible for mitigating GW/GCC/WTF by reflecting light back into space? And that emissions regulations were de-masking the problem? Confused again.

Brick, yeah,I remember exactly that also.
Yes, I remember reading just that.All the wood/coal/dung/tree/forest fires in the east were supposed to be mitigating CW.

Frankly,I don't remember the details of how it was decreasing the temp, but I'll take a stab at it.Maybe, maybe the particles were absorbing the sunlight high in the atm and then re-radiating it back into space? The idea being that instead of all the photons hitting the earth-as they normally would-some hit the carbon-and then get radiated out in all directions-and some of the directions are spaceward??

Well, I don't remember the details, but I distinctly remember the implication was that CO2 caused GW would be much worse once all those cooking fires(and other fires) were decreased.

I usually slightly favor the possibility of man released CO2 causing increased temps, but speaking out of both sides of their mouths-hmmmm.

Of course what I think has no bearing on what will happen.It won't be put up for a vote(well, it might be in some respects).I don't think we will manage to decrease CO2 production anytime soon.

Charlie

Based on my incomplete understanding, there are still major unknowns about aerosols. But here's a short summary. Black carbon aerosols heat the troposphere directly by absorbing visible light at re-radiating the energy as heat (long IR). Sulfate and similar aerosols cool the troposphere indirectly by acting as cloud condensation nuclei. The puffy white clouds reflect some of the incoming visible light so that energy exits the earth balance. Clouds that form at different atmospheric levels can have different energy-balance effects, and that's where my understanding runs out.

Black carbon aerosols can also settle out on terrestrial surfaces. If those surfaces have a high albedo (reflectivity) like snow, then the BC increases heat absorbed at the surface. Particles that have albedo similar to the surface they deposit on won't change energy balance.

I have a pdf of Shindell and Faluvegi 2009 from Nature Geoscience that I can (sub-legally) share in response to PM requests. It is mostly outside my comprehension but maybe you'll do better with it.

As usual, I would not agree with a popular media assessment that the most important thing is that BC is little talked about. The important things are that we can't yet pin down all the mechanisms, that the sources in time and space are poorly constrained, and that the technology. politics and economics of source reduction are not at all worked out. 2/3 of those apply to CO2 as well.

I completely agree with phoebeisis that CO2 emissions will continue and increase because that' s where the big money is. Conservation and renewables will at best slow the rate of CO2 emissions growth for two decades (+/-). Whether we use biology, geology, or space technology to mitigate changes is totally undecided at this point. Possible climate scenarios for this century cover a wide range, especially if one includes the perspectives of "CO2 enthusiasts". But for sure we're going to find out, because the great experiment is already underway.

DAS

I like that your 666th post is an explanation of black carbon emissions. :D But thanks for that. It sounds plausible enough.