Humans 'may have lost control' of rate of Antarctic ice sheet melting

Melting in West Antarctic expected to 'accelerate dramatically' regardless of cuts in fossil fuel, study author warns

Warming oceans are eroding the West Antarctic Ice Sheet from underneath. Getty Images

One of the Antarctic’s most important ice features faces inevitable melting that will contribute to climate change, researchers said on Monday.

They fear humans “may have lost control” of the West Antarctic Ice Sheet, meaning that even if efforts to control emissions are successful, its loss will continue to accelerate this century, a study published in Nature Climate Change found.

Study lead author Dr Kaitlin Naughten, from the British Antarctic Survey, said other research points to it contributing to a sea level increase of about one metre by 2100.

“Our study suggests that regardless of how much we reduce fossil fuels, melting of West Antarctic ice shelves – the floating parts of the ice sheet around the edges – can be expected to accelerate dramatically over the next century,” she told The National.

Warming oceans erode the ice sheet from underneath and this effect is most pronounced on the western side of the continent.

“The West Antarctic Ice Sheet is the most vulnerable part of Antarctica because most of it is below sea level,” Dr Naughten added.

“This means the ocean could melt its way beneath the glaciers and melt them from the bottom up. Even a tiny increase in ocean temperatures would lead to ice loss.”

If the entire West Antarctic Ice Sheet melted, it would contribute to a roughly five-metre rise in sea levels, though that scenario is considered unlikely, BAS said.

East Antarctica, which contains about 95 per cent of the continent’s ice, remains stable as far as scientists can see.

“It appears we may have lost control of the West Antarctic Ice Sheet melting over the 21st century,” she said.

“Our actions today likely will make a difference further down the line in the 22nd century and beyond, but that’s a timescale that probably none of us here will be around to see.”

A recent study found the amount of ice has been increasing there over the past 30 years, though it is rapidly melting in the west, with a net loss of about 7.5 trillion tonnes of ice.

“This is a sobering piece of research,” said Prof Alberto Naveira Garabato, an oceanographer at the University of Southampton.

“It illustrates how our past choices have likely committed us to substantial melting of the West Antarctic Ice Sheet and its consequent sea level rise – to which we will inevitably have to adapt as a society over coming decades and centuries.

“However, it should also serve as a wake-up call. We can still save the rest of the Antarctic Ice Sheet, containing about 10 times as many metres of sea level rise, if we learn from our past inaction and start reducing greenhouse gas emissions now.”

How much the melting will contribute to rising oceans is not as well understood as other polar regions such as the Greenland glaciers.

For the current study, Dr Naughten’s BAS team simulated four scenarios for the 21st century, imagining that emissions are either controlled to rein in the global temperature rise to 1.5°C or 2°C above pre-industrial levels or that emissions continue at a medium or high level.

Each scenario showed there would be widespread warming of the Amundsen Sea, which borders West Antarctica, resulting in faster melting of the ice sheets.

The various emissions pathways did not show much difference until around 2045 when the high-emissions simulation began to increase the rate of melting faster than the other scenarios.

The study suggests an inevitable rise of sea levels that will likely devastate many coastal communities if they do not adapt.

Millions of people around the world, who live by the coast, will either have to “build around” or abandon areas, Dr Naughten said,

Already in the UK the Welsh village of Fairbourne is scheduled for abandonment in the 2050s.

Other scientists cautioned against viewing the results of the study as being conclusive as they are based on a single model, but that it is in line with other similar studies.