Friday, July 24, 2009

Look to the skies

Consulting with clouds: A clear role in climate change

Interesting story on new research on clouds and their likely future role in global warming. The news doesn't sound great:
Using observational data collected over the last 50 years and complex climate models, the team has established that low-level stratiform clouds appear to dissipate as the ocean warms, indicating that changes in these clouds may enhance the warming of the planet.
Furthermore, this is something that a lot of current models don't show this, apparently:
...most of the state-of-the-art climate models from modeling centers around the world do not reproduce this cloud behavior. Only one, the Hadley Centre model from the U.K. Met Office, was able to reproduce the observations. "We have a long way to go in getting the models right, but the Hadley Centre model results can help point us in the right direction," said co-author Burgman, a research scientist at the University of Miami.

Together, the observations and the Hadley Centre model results provide evidence that low-level stratiform clouds, which currently shield the earth from the sun's radiation, may dissipate in warming climates, allowing the oceans to further heat up, which would then cause more cloud dissipation.

Presumably, poor modelling of cloud behaviour could have something to do with the recently reported study that CO2 alone did not account for anywhere near enough warming at PETM, 55 million years ago. Skeptics took the uncertainty from that study as encouragement. People like me took as more of a sign that we should be uneasy that warming from CO2 could be at the high end of the current estimates due to poorly unstood feedbacks.

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