Antarctic melt ‘to cause 50cm sea level rise’: new study

A new study suggests a significant increase on previous estimates, uncovering ‘substantial changes’ in atmospheric and oceanic circulation patterns.

Melting of the Antarctic icesheet could “conservatively” cause half a metre of sea-level rise in the coming century, a significant increase on some previous estimates, a new study suggests.

The global collaboration, led by scientists at the University of Tasmania and Australian National University, revealed “substantial changes” in atmospheric and oceanic circulation patterns around the icesheet.

“These changes noticeably affect the Antarctic icesheet and result in sea-level rise,” said lead author Dr Taryn Noble, from UTAS’ Institute for Marine and Antarctic Studies.

“We also highlight that the fastest rates of change occur in portions of the icesheet that cover large basins extending below sea level.

“These regions experience the greatest change because they are the most directly affected by the warming ocean, a condition that exists in both West and East Antarctica.”

Using data and modelling for past warm periods, the assessment suggests that Antarctic ice melt alone – not including melt from the Arctic and other continental glaciers – could contribute about 50cm sea-level rise per century.

Dr Noble said this was significantly higher than the 15cm estimated by the Intergovernmental Panel on Climate Change in 2013.

However, she said there was a high level of certainty around the 50cm figure because it was “quite conservative” and underpinned by knowledge of how the Antarctic icesheet had responded to past periods of warming.

Sea level rise of 50cm would bring major challenges for coastal and island human settlements. “We’re talking increased flooding, coastal erosion, salinisation of agricultural land, impacts on estuaries and ports,” Dr Noble said.

The extra freshwater released from the melting icesheets could have significant implications for climate change and Antarctica’s ocean ecosystems and fisheries.

“Adding all that freshwater to the ocean will change the amount of sea ice, which is something that grows and melts every year and has ecological importance for krill and the big fisheries sustained by Antarctic krill,” she said.

More work was needed to better understand how the Antarctic landmasses may rise as heavy icesheets melted, potentially reducing the rate of ice loss.

“Suddenly, there is a lack of ice and the continent jumps up a bit and that can actually help slow down the rate that ice is lost in certain parts of West Antarctica, in particular,” she said.

The peer-reviewed study examined satellite observations, other observations of the atmosphere, ocean, sea ice and land ice, computer modelling, past variations – based on ice cores and sea floor samples – as well as detailed sea-floor maps, geophysical observations and modelling of the earth structure under the icesheet.