Stéphane ORJOLLET –
As Antarctica became the latest place on Earth to smash its high temperature record, new studies are alerting humanity to the risks of continuing to warm the continent that is home to enough frozen water to lift global sea levels dozens of metres.
On February 9, a team of researchers on Seymour Island, part of an archipelago curving off the northern tip of Antarctica, measured 20.75 degrees Celsius (69.35 Farenheit), the first time anywhere on the continent had broken the 20-C barrier.
“We’d never seen a temperature this high in Antarctica,” Brazilian scientist Carlos Schaefer said.
That record came hot on the heels of an already alarming temperature peak, with the mercury hitting 18.3C at the Argentinian Esperanza research base on February 7.
“We can’t use this to anticipate climatic changes in the future. It’s a data point,” said Schaefer.
“It’s simply a signal that something different is happening in that area.”
While it can be tricky to definitively link climate change to individual weather events there is little doubt that such high temperatures aren’t good news for Antarctica.
And they fit a long-term trend of global warming.
The last decade was the hottest in recorded history, and the last five years have been the five hottest on record.
January 2020 was the hottest January scientists had ever witnessed, and Earth’s poles are warming quicker than much of the rest of the planet.
Two studies this week sounded the alarm on what rising land and sea temperatures could mean for the continent’s vast ice sheets.
One published on Friday in the Earth System Dynamics review found that Antarctic melting could raise sea levels up to 58 centimetres by the end of this century — constituting a trebling of last century’s pace.
“The ‘Antarctica Factor’ turns out to be the greatest risk, and also the greatest uncertainty, for sea-levels around the globe,” said lead-author Anders Levermann from the Potsdam Institute of Climate Impact Research. The team behind the study said that rapid cuts to greenhouse emissions in line with the Paris Agreement on climate change could help limit the ice-sheet loss.
But with emissions creeping higher every year, the world is likely to have to grapple with significant disruption to coastal communities by 2100.
“What we know for certain is that not stopping the burning of coal, oil and gas will drive up the risks for coastal metropolises from New York to Mumbai, Hamburg or Shanghai,” said Levermann.
A second study by Australian researchers published on Wednesday in the PNAS journal, looked into the deep past to predict future sea-level rises. They studied the last of Earth’s interglacial periods, between 129,000 and 116,000 years ago.
Measuring isotopes from volcanic ash in ice samples, the team identified a gap in the ice sheet record that indicated mass sea-level rise as temperatures warmed.
At the time, Earth’s oceans were roughly 2C hotter than currently, and the team estimated the effect that had on Antarctica’s vast western ice sheet.
The sheet rests on the sea bed and so is extremely vulnerable to temperature rises.
“The melting was likely caused by less than 2°C ocean warming — and that’s something that has major implications for the future, given the ocean temperature increase and West Antarctic melting that’s happening today,” said Chris Turney, professor in Earth and Climate Science at UNSW Sydney and lead author of the study.
The United Nations Intergovernmental Panel on Climate Change says that melting ice sheets have already contributed 15 centimetres to sea levels since the start of the 20th Century. As a consequence, by mid-century more than one billion people will live in areas particularly vulnerable to storm surges made worse by higher seas. — AFP