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Three Trillion Tonnes of Ice Lost from Antarctica Since 1992

Antarctica has lost about 3 trillion tonnes of ice since 1992, enough to raise global sea levels by 8 mm, according to a report published in Nature (https://goo.gl/kqK28p).

Antarctica’s ice sheets contain enough water to raise global sea level by 58 metres. Understanding the current ice-sheet mass balance — the net balance of mass gains and losses — is key to estimating potential future changes in ice-sheet mass as the global climate warms. More than 150 calculations of ice-mass loss from Antarctica have been made since 1989.

Using 24 different satellite-based estimates, an international team of researchers found that warm oceans have driven a tripling of ice loss – from 53 billion to 159 billion tonnes per year – in Western Antarctica between 1992 and 2017.

Ice loss on the Antarctic Peninsula alone increased from about 7 billion to 33 billion tonnes per year. However, East Antarctica’s mass balance remains highly uncertain and is indistinguishable from zero.

A separate report in Nature (https://goo.gl/Q6XZQq) led by Dr Steve Rintoul of CSIRO’s Centre for Southern Hemisphere Oceans Research explored how Antarctica and the Southern Ocean will change over the next 50 years depending on greenhouse gas emissions over that time. This study warned that if emissions remain unchecked, by 2070 major ice shelves will have collapsed, sea level rise will have accelerated to rates not seen in 20,000 years, and ocean acidification and over-fishing will have altered Southern Ocean ecosystems. However, if strong action is taken to limit emissions then Antarctica’s ice shelves will remain intact and will make only a small contribution to sea level rise.

“Continued high greenhouse gas emissions risk committing us to changes in Antarctica that will have long-term and far-reaching consequences for Earth and humanity,” Rintoul said. “Greenhouse gas emissions must start decreasing in the coming decade to have a realistic prospect of following the low emissions narrative and so avoid global impacts, such as substantial sea level rise.”

Co-author Prof Steven Chown of Monash University’s School of Biological Sciences added: “Global sustainability depends on a rapidly closing window of opportunity. If we take action now to limit greenhouse gas emissions, Antarctic environments will remain much as we have come to know them over the past 200 years. If we do not, they will change dramatically, and through their connections to the rest of the Earth system, result in global impacts with irreversible consequences.”