A new analysis of temperature records indicates
that the Western Antarctic Ice Sheet is warming nearly twice as fast as
previously thought.US researchers say they found the first evidence of warming during the southern hemisphere's summer months. They are worried that the increased melting of ice as a result of warmer temperatures could contribute to sea-level rise.
The study has been published in the journal Nature Geoscience.The scientists compiled data from records kept at Byrd
station, established by the US in the mid-1950s and located towards the
centre of the West Antarctic ice sheet (WAIS).Previously scientists were unable to draw any conclusions from the Byrd data as the records were incomplete. The new work used a computer model of the atmosphere and a numerical analysis method to fill in the missing observations.
The results indicate an increase of 2.4C in average annual temperature between 1958 and 2010.
"What we're seeing is one of the strongest warming signals on
Earth," says Andrew Monaghan, a co-author and scientist at the US
National Centre for Atmospheric Research.
"This is the first time we've been able to determine that there's warming going on during the summer season." he added.
Top to bottom
It might be natural to expect that summers even in Antarctica
would be warmer than other times of the year. But the region is so cold,
it is extremely rare for temperatures to get above freezing
Top to bottom
It might be natural to expect that summers even in Antarctica
would be warmer than other times of the year. But the region is so cold,
it is extremely rare for temperatures to get above freezing.
“This place has very variable weather, some of it is influenced by human acts and some of it isn't ”
Prof David Bromwich Ohio State University
According to co-author Prof David Bromwich from Ohio State University, this is a critical threshold.
"The fact that temperatures are rising in the summer means
there's a prospect of WAIS not only being melted from the bottom as we
know it is today, but in future it looks probable that it will be
melting from the top as well," he said.
Previous research published in Nature
indicated that the WAIS is being warmed by the ocean, but this new work
suggests that the atmosphere is playing a role as well.
The scientists say that the rise in temperatures has been
caused by changes in winds and weather patterns coming from the Pacific
Ocean.
"We're seeing a more dynamic impact that's due to climate
change that's occurring elsewhere on the globe translating down and
increasing the heat transportation to the WAIS." said Dr Monaghan.
But he was unable to say with certainty that the greater warming his team found was due to human activities.
"The jury is still out on that. That piece of research has
not been done. My opinion is that it probably is, but I can't say that
definitively."
This view was echoed by Prof Bromwich, who suggested that further study would be needed.
source: bbc.com
