Temperatures on the northern Antarctic Peninsula can reach a balmy 5C on a warm summer’s day. It’s not quite T-shirt weather, but this is Antarctica, after all. So at first glance, the two Antarctic temperature records set last week – 18.3C at the Argentine Esperanza base on 6 February and 20.8C at Brazilian base Marambio on 9 February – appear extraordinary.
And they are – but these records need context. Both highs are associated with a weather phenomenon called “foehn”, German for “hairdryer”, which occur all over the world when air is forced over steep terrain. When winds blow over the Antarctic Peninsula’s high mountains, it can produce a warming, drying “foehn effect” on the other side, which can cause temperatures to soar by 20-30C for hours or days at a time.
However, while these two new temperature records – hit within days of each other – are related to a natural weather phenomenon, they are set against a backdrop of ongoing Antarctic climate change. According to NASA, 2019 was the second warmest on record, and in the entire historical record, we have not seen a warmer January than this year’s recorded temperature. Until recently, the Antarctic Peninsula was the fastest-warming region on Earth, heating by 3C since the mid-20th-century. Warmer average conditions mean foehn events increase temperatures from a warmer starting point, so records can continually be broken.
That warming comes with consequences, too. Since the 1940s, more than half of the peninsula’s floating ice shelves have collapsed, and more than 90 per cent of the region’s glaciers have retreated. In fact, the loss of two of the peninsula’s floating ice shelves in 1995 and 2002 (Larsen A and B) has been linked to the increasing frequency of foehn winds, which can destabilise ice shelves enough to cause them to collapse in spectacular fashion. Without ice shelves holding them back, glaciers on the peninsula can flow unrestrained into the sea, contributing to sea level rise.
Across the whole continent, ice loss from glaciers and ice shelves has added around 14mm to global sea level rise since 1979, with 63 per cent of that coming from the West Antarctic ice sheet. And this is happening at an accelerating rate – the amount of ice lost from Antarctica in 2009-2017 was six times higher than in 1979-89. This is especially keenly felt in the West Antarctic, which contains enough ice to raise global sea levels by several metres.
West Antarctica has become a focal point for polar scientists, who are rushing to understand the causes and likely outcomes of rapid change there. The rate of ice loss from Thwaites glacier, the subject of a major international collaboration, has doubled in the last 30 years, while the neighbouring Pine Island Glacier, the fastest shrinking glacier on Earth, spawned an iceberg last week that was half the size of Greater London. Events in the frozen parts of our planet continue to surprise polar scientists, and the key to predicting future change is to understand the present.
I’m a climate scientist, and I deal every day with the kind of worrying truths that induce “climate anxiety”. When you work on the polar regions, the statistics are even more stark because they are where we see the most dramatic and fast-occurring changes. The poles are also the places where we are seeing change at a much faster rate than predicted: for instance, the heatwave of July 2019 in Greenland caused levels of surface melting projected for 2070, not 2019.
Being able to go to Antarctica and be involved in polar research is an immense privilege, and one that sharpens my resolve to tackle the climate crisis. Antarctica is a truly special place, the last great wilderness, and a scientific continent with enormous significance.
What we’ve learned from events like the unexpected collapse of Larsen B or the record-breaking heatwaves seen last week is that events in the polar regions can take you by surprise. There is so much we don’t yet know about Antarctica. Polar science gives us the keys to our past, present and future, and unlocking those answers has never been more important.
Ella Gilbert is an atmospheric physicist at the British Antarctic Survey