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Global warming – faster and hotter than we thought?

Future warming likely to be on high side of climate projections, analysis finds  , Eureka Alert 8 Nov 12 BOULDER—Climate model projections showing a greater rise in global temperature are likely to prove more accurate than those showing a lesser rise, according to a new analysis by scientists at the National Center for Atmospheric Research (NCAR). The findings, published in this week’s issue of Science, could provide a breakthrough in the longstanding quest to narrow the range of global warming expected in coming decades and beyond.

NCAR scientists John Fasullo and Kevin Trenberth, who co-authored the
study, reached their conclusions by analyzing how well sophisticated
climate models reproduce observed relative humidity in the tropics and
subtropics.

The climate models that most accurately captured these complex
moisture processes and associated clouds, which have a major influence
on global climate, were also the ones that showed the greatest amounts
of warming as society emits more greenhouse gas into the atmosphere.

“There is a striking relationship between how well climate models
simulate relative humidity in key areas and how much warming they show
in response to increasing carbon dioxide,” Fasullo says. “Given how
fundamental these processes are to clouds and the overall global
climate, our findings indicate that warming is likely to be on the
high side of current projections.”

The research was funded by NASA.

—–Moisture, clouds, and heat—–

The world’s major global climate models, numbering more than two
dozen, are all based on long-established physical laws known to guide
the atmosphere. However, because these relationships are challenging
to translate into software, each model differs slightly in its
portrayal of global climate. In particular, some processes, such as
those associated with clouds, are too small to be represented
properly.

The most common benchmark for comparing model projections is
equilibrium climate sensitivity (ECS), or the amount of warming that
eventually occurs in a model when carbon dioxide is doubled over
preindustrial values. At current rates of global emission, that
doubling will occur well before 2100…..
http://www.eurekalert.org/pub_releases/2012-11/ncfa-fwl110512.php

November 9, 2012 - Posted by Christina Macpherson | climate change