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Threat of Sea Level Rise Intensifies as Antarctica's Melting Ice Sheet at 'Point of No Return'

Climate

British researchers have reinforced recent evidence that melting in the Antarctic caused by the warming of the Southern Ocean could ultimately lead to global sea levels rising by around 3 meters or nearly 10 feet.

Their findings are in line with the results of a study that said six more decades of ocean warming could destabilize the ice beside the Amundsen Sea, starting a cascade of ice loss that would continue for centuries.

Mount Tyree, in the Ellsworth mountains, is Antarctica’s second highest peak. Photo credit: Christian Stangl / Wikimedia Commons

That 2015 study, which used computer simulations, was the work of scientists from the Potsdam Institute for Climate Impact Research in Germany.

But the UK scientists used a much more direct method of assessing the landscape to establish how the West Antarctic ice sheet might respond to increasing global temperatures. They just examined the mountain tops that stick up above the ice.

Levels of Ice

In what they say is the first study of its kind, the researchers were able to work out how the levels of ice covering the land have changed over hundreds of thousands of years by examining the peaks protruding through the ice in the Ellsworth Mountains, on Antarctica’s Atlantic flank.

The team from the University of Edinburgh, Northumbria University and Scottish Universities Environmental Research Centre assessed the changes on slopes at various heights on the mountainside, which showed the levels previously reached by the ice sheet.

They also plotted the distribution of boulders on the mountains deposited by melting glaciers and used chemical technology—also known as exposure dating—to show how long rocks had been exposed to the atmosphere and how old they were.

The scientists report in Nature Communications that their results show how, during previous warm periods, a substantial amount of ice would have been lost from the West Antarctic ice sheet by ocean melting.

But it would not have melted entirely, which they say suggests that ice would have been lost from areas below sea level, but not on upland areas. The study shows that parts of the West Antarctic ice sheet have existed continuously for at least 1.4 million years.

John Woodward, professor of physical geography at Northumbria University, is one of the leaders of the study, which was supported by the UK’s Natural Environment Research Council and the British Antarctic Survey.

He said: “It is possible that the ice sheet has passed the point of no return. If so, the big question is how much will go and how much will sea levels rise.”

His fellow leader, Dr. Andrew Hein, research fellow and manager of the University of Edinburgh’s Cosmogenic Nuclide Laboratory, said: “Our findings narrow the margin of uncertainty around the likely impact of the West Antarctic Ice Sheet on sea level rise. This remains a troubling forecast since all signs suggest the ice from West Antarctica could disappear relatively quickly.”

Massive Consequences

If the West Antarctic ice sheet were to melt altogether—something that is not likely to happen this century—the world’s sea levels would rise by 4.8 meters. That would have massive consequences for coastal communities worldwide. The melting of the West Antarctic glaciers accelerated threefold over the 21 years to 2014.

What happens to the ice sheets of the Antarctic continent could cause even more profound changes to the Earth. The East Antarctic sheet had for decades been thought to be more stable than its western neighbor, but that is now less certain.

Two scientists from Potsdam Institute for Climate Impact Research reported in 2014 that they had identified how a relatively small loss of ice there could ultimately trigger a discharge of ice into the ocean that would result in unstoppable sea-level rise for thousands of years ahead.

Another study, published in 2015, predicted a doubling of the rate at which the ice shelves across Antarctica will melt by 2050.

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"Based on the information we have, we do not believe there are any survivors on the island," the police said in their official statement. "Police is working urgently to confirm the exact number of those who have died, further to the five confirmed deceased already."

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At the time of the eruption on Monday, about 50 passengers from the Ovation of Seas were on the island, including more than 30 who were part of a Royal Caribbean cruise trip, according to CNN. Twenty-three people, including the five dead, were evacuated from the island.

The eruption occurred at 2:11 pm local time on Monday, as footage from a crater camera owned and operated by GeoNet, New Zealand's geological hazards agency, shows. The camera also shows dozens of people walking near the rim as white smoke billows just before the eruption, according to Reuters.

Police were unable to reach the island because searing white ash posed imminent danger to rescue workers, said John Tims, New Zealand's deputy police commissioner, as he stood next to Prime Minister Jacinda Ardern in a press conference, as The New York Times reported. Tims said rescue workers would assess the safety of approaching the island on Tuesday morning. "We know the urgency to go back to the island," he told reporters.

"The physical environment is unsafe for us to return to the island," Tims added, as CNN reported. "It's important that we consider the health and safety of rescuers, so we're taking advice from experts going forward."

Authorities have had no communication with anyone on the island. They are frantically working to identify how many people remain and who they are, according to CNN.

Geologists said the eruption is not unexpected and some questioned why the island is open to tourism.

"The volcano has been restless for a few weeks, resulting in the raising of the alert level, so that this eruption is not really a surprise," said Bill McGuire, emeritus professor of geophysical and climate hazards at University College London, as The Guardian reported.

"White Island has been a disaster waiting to happen for many years," said Raymond Cas, emeritus professor at Monash University's school of earth, atmosphere and environment, as The Guardian reported. "Having visited it twice, I have always felt that it was too dangerous to allow the daily tour groups that visit the uninhabited island volcano by boat and helicopter."

The prime minister arrived Monday night in Whakatane, the town closest to the eruption, where day boats visiting the island are docked. Whakatane has a large Maori population.

Ardern met with local council leaders on Monday. She is scheduled to meet with search and rescue teams and will speak to the media at 7 a.m. local time (1 p.m. EST), after drones survey the island, as CNN reported.