It is “virtually certain” that future extreme events in Antarctica will be worse than the extraordinary changes already observed, according to a new scientific warning that stresses the case for immediate and drastic action to limit global heating.
A new review draws together evidence on the vulnerability of Antarctic systems, highlighting recent extremes such as record low sea ice levels, the collapse of ice shelves, and surface temperatures up to 38.5C above average over East Antarctica in 2022 – the world’s largest ever recorded heatwave.
Records for Antarctic sea ice, which varies every year between a February minimum and a September maximum, “have been tumbling in recent years”, said study co-author Dr Caroline Holmes, a polar climate scientist at the British Antarctic Survey.
“One clear metric of how things are changing is that the summer minimum has broken a new record three times in the past seven years,” she said at a press briefing.
Sea ice extent in July 2022 hit a record low for that time of year, but was surpassed by a new record this July – one that was “three times further away from the average than what we’ve seen previously”, Holmes said.
Antarctic land ice – which contributes to sea level rise when it melts – has also declined since the 1990s, said Assoc Prof Anna Hogg of the University of Leeds, a study co-author.
Between 1992 and 2020, the Antarctic and Greenland ice sheets have contributed a 2.1cm rise to the global mean sea level.
The rate of ice sheet loss from Antarctica “matches the IPCC worst case” for predicted ice loss under high greenhouse gas emissions scenarios, Hogg said. “The observations show we’re tracking [along] the most extreme prediction of what might happen.” This is despite global emissions currently tracking closer to an intermediate emissions pathway.
Ice shelves, which fringe three-quarters of the Antarctic coastline, have also retreated in recent decades. Large sections of the Larsen-A, Larsen-B, and Wilkins ice shelves “collapsed catastrophically” in 1995, 2002 and 2008 respectively, the study noted. Ten Antarctic ice shelves have also experienced major ice calving events since 2009.
“We should be deeply concerned about the environment of Antarctica in the years that are coming under continued fossil fuel burning,” said the study’s lead author, Prof Martin Siegert of the University of Exeter.
“This is the most extreme natural laboratory on the planet. Our ability to measure and observe is very difficult … but we really must try harder to understand the processes that are causing these extreme events and their interconnectivity.”
The study noted that given additional global heating of at least 0.4C was now unavoidable, to limit heating to 1.5C as per the Paris agreement, “it is virtually certain that future Antarctic extreme events will be more pronounced than those observed to date”.
Prof Tim Naish, director of the Antarctic Research Centre at the Victoria University of Wellington, who was not involved in the research, said the increasing occurrence of extreme Antarctic events showed that “the policy response so far has been inadequate to address the climate crisis”.
“Antarctica is experiencing more and more extreme events,” he said in a statement. “In some cases we are getting dangerously close to tipping points, which once crossed will lead to irreversible change with unstoppable consequences for future generations.”
The research was published in the journal Frontiers in Environmental Science.
