Ocean heatwaves ‘virtually certain’ in Antarctic, bringing global impacts

Extreme events in Antarctica such as ocean heatwaves and accelerating ice loss will almost certainly become more common with severe knock-on impacts globally, according to a major study of the polar region.

It brings together for the first time evidence on how extreme events have affected Antarctica, and shows how they are influencing every environmental aspect of the world’s fifth largest continent, disturbing its weather, increasing dust storms and causing ice shelf collapse that could soon trigger cascading effects throughout the planet, UK researchers conclude.

Antarctica’s fragile environments “may well be subject to considerable stress and damage in future years and decades” and could take centuries to recover, their study warns.

The Antarctic is a colossal store of land ice that is 4km deep with a vast white surface deflecting sunshine to the atmosphere which keeps the Earth cool. It experienced the world’s largest recorded ever heatwave in March 2022 when temperatures were 38.5 degrees higher than normal (minus 10 degrees).

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Coastal communities throughout the world will be vulnerable to flooding and storm surges of increasing frequency and intensity, the study finds, though sea level rise of 1.8cm since the early 1990s may seem small.

As a result of ecosystem impacts the loss of marine species has increased in the Antarctic, there has been an invasion of non-native plants and, in recent years, a lack of winter sea ice formation which is currently the lowest on record.

Dust storms due to tiny particles of sand and gravel being exposed by melting ice are increasingly darkening the ice and further increasing warming, the study finds. Extreme weather events in the Antarctic will be more likely under global heating and the burning of fossil fuels in particular.

“Antarctic change has global implications,” said lead author Prof Martin Siegert of the University of Exeter. “Reducing greenhouse gas emissions to net zero is our best hope of preserving Antarctica, and this must matter to every country – and individual – on the planet.”

Prof Siegert said rapid changes happening there could place many countries in breach of an international treaty: “Signatories to the Antarctic Treaty (including the UK, US, India and China) pledge to preserve the environment of this remote and fragile place.” They “must understand that by continuing to explore, extract and burn fossil fuels anywhere in the world the environment of Antarctica will become ever more affected in ways inconsistent with their pledge”.

Their study published in the journal Frontiers in Environmental Science reviews evidence of extreme events in Antarctica and the Southern Ocean, including weather, sea ice, ocean temperatures, glacier and ice shelf systems, and biodiversity on land and sea. It examines the vulnerability of Antarctica to a range of extreme events to understand causes and likely future changes.

Extreme events can also affect biodiversity. High temperatures have been linked to years with lower krill numbers, leading to breeding failures of krill-reliant predators – evidenced by many dead fur seal pups on beaches.

Co-author Prof Anna Hogg of the University of Leeds, said: “Our results show that while extreme events are known to impact the globe through heavy rainfall and flooding, heatwaves and wildfires, such as those seen in Europe this summer, they also impact the remote polar regions. Antarctic glaciers, sea ice and natural ecosystems are all impacted by extreme events. Therefore it is essential that international treaties and policy are implemented to protect these beautiful but delicate regions.”