Glacier retreat caused by soot?

Published December 15, 2009 by Sean

New research from NASA (not sure if it’s peer reviewed, but it seems likely) suggests that soot is a major contributor to the retreat of glaciers in the Himalayas. A quick glance at William Lau’s webpage shows that dust is having several effects, directly on sunlight in the atmosphere, by darkening snow and allowing it to melt faster, and also by interacting with clouds and rainfall. Rainfall in the right location is essential for glacier mass balance to be maintained by replenishing the snowpack at the top of the mountain. The magnitude of the effect is estimated (presumably only in localised areas) as equivalent to the CO2 forcing (which must presumably then have been overestimated).

Now, this is important because carbon neutral energy is not necessarily soot free. Burning bio-fuels is maybe just as bad or worse. Diesel may be worse than petrol since the nature of the soot is different. This is a perfect example of a mechanism where fixing the wrong problem might actually make the problem worse.
Of course, from a policy point of view, this is bad news. Particulate emission is easy to manage, without the need to tax or ration energy use. Providing any electricity (clean or not) to third world countries could be a massive improvement over insisting that they can only have access to modern energy technology if it is 100% clean (otherwise they can burn dung, because that is natural).

Even if not proven, this shows how large the uncertainties are in our current understanding of climate science. If CO2 is only half the problem, maybe we should look to identify the other half as well, since fixing half of a critical issue is probably a waste of effort.

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  1. Sean says:

    Other sources suggest that he effects of sunspots are equivalent to co2 forcing as well, so does this mean that that we got the magnitude wrong by a half or that they are a third each 😉
    Sean: Come up with a provable causal mechanism for sunspots having an effect, and you’ll be famous. Until then, it’s just wiggle matching. Svensmark’s experiments appear to be inconclusive so far, and the albedo data does not reliably span enough of a cycle to draw much in the way of conclusion. CLOUD and the next 11 years will be interesting.

    Posted December 16, 2009 @ 11:04 am (UK)

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