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None More Black
An aerosol known as "black carbon," a primary component in soot, looks to be a key driver of anthropogenic global warming in tropical locations around the world -- most notably, in the Himalayan region.
...new research, by NASA’s William Lau and collaborators, reinforces with detailed numerical analysis what earlier studies suggest: that soot and dust contribute as much (or more) to atmospheric warming in the Himalayas as greenhouse gases. This warming fuels the melting of glaciers and could threaten fresh water resources in a region that is home to more than a billion people.[...] Nicknamed the “Third Pole”, the region in fact holds the third largest amount of stored water on the planet beyond the North and South Poles. But since the early 1960s, the acreage covered by Himalayan glaciers has declined by over 20 percent. Some Himalayan glaciers are melting so rapidly, some scientists postulate, that they may vanish by mid-century if trends persist. Climatologists have generally blamed the build-up of greenhouse gases for the retreat, but Lau’s work suggests that may not be the complete story.
He has produced new evidence suggesting that an “elevated heat pump” process is fueling the loss of ice, driven by airborne dust and soot particles absorbing the sun’s heat and warming the local atmosphere and land surface.
Globally, black carbon looks to be the second most-important warming agent after CO2.
Here's the twist: much of the production of black carbon comes from the combustion of biofuels and diesel, the two leading "greener" fuel technologies.
Aerosols last for months in the atmosphere, as opposed to the decades that greenhouse gases can last. This is good, as it means that policies that reduce the production of black carbon can start showing positive results in a matter of weeks.
Comments
Aren't the "biofuels" in question mostly traditional wood fires for cooking and heating, rather than biologically-derived liquid fuels? I didn't get that from the linked article but that was my understanding.
Wood burning in developing countries is pretty obviously unsustainable with current population levels & projections anyway.
Diesel is a very problematic technology because of particulates and air pollution. There is a reason why California's air quality standards effectively banned diesel cars for a while there. Sadly they didn't do much about trucks, especially older trucks, though I guess the Port of LA (? I think) effort to replace old trucks with newer, cleaner trucks has worked well, although at the cost of further reducing the ability of independent operators to participate in the trucking market. The Port of Oakland could certainly use some cleaner trucks, and it's not just an Oakland problem - when I was working near a stretch of I-80 in the city anything left near an open window would rapidly grow a layer of fine black dust.
Gasoline has its own share of problems but it seems to be easier to make it cleaner than it is for diesel. Natural gas is still better.
(If there is one thing I find more frustrating than anything else, it is the reluctance to accept natural gas as a transition fuel to replace coal and (some) oil on the grounds that, well, it's just another fossil fuel. We could be on a completely different path both for CO2 and for smog pollutants if all the coal plants built in the last 15 years had been gas plants instead. The perfect being the enemy of the good, as usual.)
Posted by: Jacob Davies | December 18, 2009 3:20 PM
So let's raise the standard of living for many of the poorest people in the world by designing more effective cooking stoves and reduce black carbon at the same time. Ancillary benefits would include better health for the women who cook and the children with them when they do it.
As for natural gas as a bridge fuel, an associate has heard that a couple of times this week at MIT. Looks like the idea may be catching on. Now, if only there is an effort to engineer a zero methane emissions system in its use I'll be happy.
Posted by: gmoke | December 18, 2009 4:46 PM