[asa] AGU 2008: Evidence that Antarctica has warmed significantly over past 50 years

From: Rich Blinne <rich.blinne@gmail.com>
Date: Fri Dec 19 2008 - 20:23:49 EST

From Nature Blogs:
http://blogs.nature.com/climatefeedback/2008/12/agu_2008_evidence_that_antarct.htmlNew
research presented at the AGU today suggests that the entire Antarctic
continent may have warmed significantly over the past 50 years. The study,
led by Eric Steig of the University of Washington in Seattle and soon to be
published in Nature, calls into question existing lines of evidence that
show the region has mostly cooled over the past half-century.

Steig and colleagues combined satellite thermal infra-red collected over 25
years with weather station data for the region. Although the satellite data
span a shorter time period and are accurate only for blue sky days i.e. when
there is no cloud cover, they provide high spatial coverage of the region,
which cannot be obtained from discrete ground measurements. In contrast, the
weather station data provide complete temporal resolution over the past
half-century.

Using an iterative process to analyse the data, they found warming over the
entire Antarctic continent for the period 1957-2006. Restricting their
analysis to 1969 to 2000, a period for which other studies have found a net
cooling trend, Steig's study found slight cooling in east Antarctica, but
net warming over west Antarctica.

As well as uncovering evidence of warming over a wider region than previous
studies have shown, the researchers found that warming occurred throughout
all of the year and was greatest in winter and spring. In contrast, cooling
over east Antarctica was restricted to autumn.

They independently confirmed these trends by using data from automatic
weather stations, and excluding the satellite data.

Overall, the study suggests that warming is not limited to the Antarctica
peninsula region. Steig says their findings are backed up by recent results
from David Bromwich of the Byrd Polar Research Centre at Ohio State
University also presented at this meeting and by a climate modelling study
using data assimilation from Hugues Goosse of the Université Catholique de
Louvain in Belgium and colleagues, which is due to be published in the
journal Climate Dynamics.

The authors speculate that the warming trend may be due to shifts in
circulation coupled with sea ice changes.

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Received on Fri, 19 Dec 2008 18:23:49 -0700

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