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While sea ice grows, Antarctica sheds land ice

The airstrip is MELLLLTING!

A new satellite survey of Antarctica suggests that some of the continent’s contribution to sea-level rise may be overestimated. However, the land ice melt on the frozen continent is still sufficient to put Australia’s multi-million dollar airstrip at risk.

However the University of Tasmania-led study, based on GRACE (Gravity Recovery and Climate Experiment) satellite data, has found that some areas of the Antarctic are not only losing ice mass rapidly, but also at an accelerating rate.

Professor Matt King, who led the study, described the study as “re-calibrating the scales”, explaining that estimates of the mass of Antarctic land ice need to take into account the land mass underneath. Scientists’ estimate of the total mass is affected by phenomena as small as the millimetres-per-year that the continent is moving.

That recalibration, he says, puts the Antarctic’s current contribution to sea level rise at the “lower end of the ice-melt spectrum”, he said. However, “the parts of Antarctica that are losing mass most rapidly are seeing accelerated mass loss and this acceleration could continue well into the future.

“The sea level change we’re seeing today is happening faster than it has for centuries with just a small contribution from the massive Antarctic ice sheet. What is sobering is that sea levels will rise even faster if Antarctica continues to lose … more ice into the oceans.”

The study, published in Nature, is a joint project with the UK’s National Environment Research Council.

The land ice melt, which incidentally far outweighs the small sea-ice gain at the periphery of the continent, is proving inconvenient for Australian research in Antarctica. Fairfax reports that the $AU46 million airstrip opened in 2008 is becoming unusable due to the melt.

The Wilkins airstrip, near Australia’s Casey research station, has managed only six landings in the last two summers rather than the planned 20 landings per summer. Alternative – but expensive – sites are under investigation.

Explaining the problem, the Antarctic Division’s chief scientist, Nick Gales, has told a parliamentary committee that melting trends outpaced “almost any records”. ®

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