#CLIMATE CHANGE: WEST #ANTARCTICA ICE SHEET (WAIS) WARMING AT 3x RATE OF REST OF PLANET

 

WAISResearchers’ analysis focuses on the temperature record from Byrd Station (indicated by star), the only source of long-term temperature observations in the area.  Black circles indicate locations of the continent’s other permanent recording stations.  The map uses color intensity to indicate the extent of warming on the ice sheet itself.    Image credit:  Julien Nicolas, courtesy of OSU

A new study by Ohio State University researchers, based on 50 years of temperature recording at Byrd Station, determines that the West Antarctica ice sheet (WAIS) is melting nearly twice as much as scientists had estimated and at triple the rate the rest of the planet is warming.

Byrd Station temperature records show an increase of 4.3 degrees F in annual temperature since 1958.

NASA-WAIS1Graphic representation of ice shelf thickness changes in meters per year   Image credit NASA

“Our record suggests that continued summer warming in West Antarctica could upset the surface mass balance of the ice sheet, so that the region could make an even bigger contribution to sea level rise than it already does,” said David Bromwich, professor of geography at Ohio State University and senior research scientist at the Byrd Polar Research Center.

“Even without generating significant mass loss directly, surfaces melting on the WAIS could contribute to sea level indirectly, by weakening the West Antarctic ice shelves that restrain the region’s natural ice flow into the ocean.”

Added to melting caused by a rise in surface temperatures, a recent study using NASA satellite data shows the WAIS is, according to the AP, “being eaten away from below by warm water.”   What’s being eaten away are the ice shelves that hold back a lot of Antarctic glacial ice from reaching the sea.

A separate study published earlier in the year in Nature about the basal melting of ice shelves concluded “It is reduced buttressing from the thinning ice shelves that is driving glacier acceleration and dynamic thinning.

“This implies that the most profound contemporary changes to the ice sheets and their contribution to sea level rise can be attributed to ocean thermal forcing that is sustained over decades and may have already triggered a period of unstable glacier retreat.

Bromwich concurs.  “Lots of melting can do lots of damage to the ice shelves, . . ” and that can ramp up Antarctica’s contribution to sea level rise worldwide.  “We know that these melting events can happen today, and we are likely to see more melting events.”

He believes more and reliable data about the WAIS is needed.   Nearly one third of temperature observations was missing for the time period of the study, partly because the station hasn’t always been occupied.  An automated station installed in 1980 experiences frequent power outages, usually during the long polar nights, when its solar panels can’t recharge.

The scientist says, “West Antarctica is one of the most rapidly changing regions on Earth, but it is also one of the least known.  Our study underscores the need for a reliable network of meteorological observations through West Antarctica so that we can know what is happening—and why—with more certainty.”

Sources:  Science 2.0, December 26, 2012      SmartPlanet Daily, December 26, 2012      Think Positive, December 27 and April 27, 2012       Study published in Nature Geoscience, December 23, 2012

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