Antarctica has lost about three trillion tonnes of ice since 1992 and scientists say the window of opportunity to prevent major meltdown of the icesheets is narrowing.
Summer clouds swirl in around the Staccato Peaks of Alexander Island, Antarctic Peninsula. Between 2012 and 2017 Antarctica lost 219 billion tonnes of ice per year. Photo: Hamish Pritchard
The ice loss corresponds to a sea level rise of around 8mm, according to a major climate assessment known as the Ice Sheet Mass Balance Inter-comparison Exercise, published in the journal Nature.
The findings show that before 2012, Antarctica lost ice at a steady rate of 76 billion tonnes per year - a 0.2mm per year contribution to sea level rise. However, since then there has been a sharp, threefold increase.
Between 2012 and 2017 the continent lost 219 billion tonnes of ice per year - a 0.6mm per year sea level contribution.
The ice sheets of Antarctica hold enough water to raise global sea level by 58 metres and knowing how much ice it is losing is key to understanding the impacts of climate change today and in the future, according to the assessment.
Andrew Shepherd of the University of Leeds, who leads the Ice sheet Mass Balance Inter-comparison Exercise (Imbie), said it had long been suspecting changes in Earth's climate would affect the polar ice sheets.
"According to our analysis, there has been a step increase in ice losses from Antarctica during the past decade, and the continent is causing sea levels to rise faster today than at any time in the past 25 years. This has to be a concern for the governments we trust to protect our coastal cities and communities."
Icebergs grounded near Adelaide Island, Antarctica Peninsula. Photo: Associate Professor Nick Golledge
Another study, also published in Nature, explores how Antarctica and the Southern Ocean will change over the next 50 years, and what impact the changes will have on the rest of the globe.
It considers the future if emissions continue to rise unchecked, and one where strong action is taken to limit emissions and manage human activity on Antarctica.
It predicts that if emissions remain high, 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. The Antarctic environment will have degraded from the failure to manage increased human pressures on the continent.
However, if emission were low, the ice shelves would remain intact, Antarctica would make a small contribution to sea level rise, and the continent would remain a "natural reserve, dedicated to peace and science" as agreed by Antarctic nations in the late 20th century.
Professor Tim Naish from the Antarctic Research Centre at Victoria University said the good news is there was still time to prevent major meltdown of the icesheets, but that timeframe is short.
He said emissions would have to peak in the next decade, then reduce to zero before the end of the century.
"Urgent action is needed. Put simply if we cannot collectively tackle climate change, then it's unlikely we will maintain Antarctica as a place for peace, nature and science."
Unusual iceberg at Rothera Research Station, Antarctic Peninsula. Scientists say the Antarctic ice melt is causing sea levels to rise faster today than at any time in the past 25 years. Photo: Andrew Shepherd
Leeds University scientists ice coring at George VI Ice Shelf, Antarctica Photo: Ian Potten
