Original URL: http://www.theregister.co.uk/2009/12/15/soot_bigger_than_co2/

Soot warming 'maybe bigger than greenhouse gases' - NASA

Forget Copenhagen CO2 cuts, tune your diesel properly

By Lewis Page

Posted in Science, 15th December 2009 12:16 GMT

Researchers from NASA's Goddard Space Flight Centre, also the home of famous carbopocalypse doom-prophet James Hansen, have repeated earlier assertions that atmospheric soot may be as important as greenhouse gases in driving global warming.

This could be good news for humanity, as atmospheric soot levels would be much easier to reduce. Filtering soot out of exhausts from diesel engines and coal burners is simple compared to removing and sequestering CO2, and as an added benefit the effects would be rapid: soot doesn't persist in the atmosphere for long periods the way greenhouse gases do, as it is washed out by rain or snow. However, many environmental campaigners would resist the idea of soot taking centre stage, fearing that this could lead to a reduced emphasis on greenhouse-gas emissions reductions.

Himalayan glaciers feed many of the great rivers of southern Asia. Credit: NASA

Ice running off the gutters of the 'roof of the world'.

Earlier investigations including the effect of soot had focused on the Arctic, where Goddard scientists have previously suggested that "the impact of aerosols is just as strong as that of the greenhouse gases". Aerosols include soot, which tends to heat the atmosphere, plus sulphates and others which cool it. Unfortunately sulphates also cause acid rain, and clean-air regs in the US and Europe have seen them massively reduced - and the Arctic warm up.

Now, Goddard researchers have carried out new investigations into the effects of sooty aerosols on the glaciers of the Himalayas - sometimes known as the planet's "Third Pole". Glacial melting in the Himalayas has received a lot of play in the greenly-inclined media lately against the background of the COP15 international climate talks underway in Copenhagen; it is widely felt that the mountain ice is disappearing much faster even than CO2-alarmist climate models predict, and that this is a reason to suggest that the Copenhagen talks - focused entirely on greenhouse-gas emissions - may be the last chance for humanity to save itself from a disastrous climate apocalypse.

Forget about burping cows, airliners and green IT - just tune up your diesel engine and chip in towards modern stoves for everyone

But according to NASA this week:

The 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.

"We need to add another topic to the climate dialogue," says Lau.

Hal Maring of NASA headquarters goes further, though he cautions that more field results from the "roof of the world" are necessary to validate Lau's modelling.

"Even at this stage we should be compelled to take notice," says Maring. “Airborne particles have a much shorter atmospheric lifespan than greenhouse gases, so reducing particle emissions can have much more rapid impact on warming.”

One of the most troublesome types of aerosol is "black carbon", dark particulate soot emitted when fuel is incompletely burned. Diesel engines are a particular villain here, but coal burning and primitive cooking are also big contributors. If the new research is right, huge reductions in warming are on offer from comparatively easy initiatives such as better stoves, more efficient modernised diesel engines and cleaner coal powerplants, boilers etc. These measures would also take effect much more quickly than comparatively difficult, expensive and unpopular cuts in emissions of greenhouse gases like CO2 or methane.

Even Lau's Goddard colleague Dr James Hansen, who has spent the last several decades relentlessly bigging-up the greenhouse gas threat and pushing for emissions cuts, now admits that soot is a major issue - though he can't bear to suggest it might actually be bigger than greenhouse gases.

"Black soot is probably responsible for as much as half of the glacial melt," he says.

It seems that the assembled, warring delegates at the Copenhagen greenhouse-gas talks - trying to prevent global temperature rises in the next few decades, ie in the fairly short term - may be arguing over the wrong things. According to the latest NASA research the human race might achieve more by sorting out its soot emissions first, a thing which would be comparatively easy to do, and get to the much more difficult, unpopular and less effective greenhouse gas cuts afterwards. ®