Polar ice sheets may collapse even if 1.5°C target is met, scientists warn

The polar ice sheets are unlikely to remain intact even if the world manages to keep climate change to within the 1.5°C increase as established under the Paris Climate Agreement.

According to a team of researchers led by Durham University, global temperatures should instead be closer to 1°C above pre-industrial temperatures to avoid significant losses from the polar ice sheets and prevent a further acceleration in sea level rises.

The findings suggest a gloomy future for the world’s ice sheets as global warming is thought to have exceeded the 1°C threshold as far back as 2015. In January, the Copernicus Climate Change Service said 2024 even exceeded the 1.5°C threshold, albeit temporarily.

The Durham team reviewed a wealth of evidence to examine the effect that the 1.5°C target would have on the ice sheets in Greenland and Antarctica, which together store enough ice to raise global sea levels by almost 65 metres.

The mass of ice lost from these ice sheets has quadrupled since the 1990s and they are currently losing around 370 billion tonnes of ice per year. 

The authors argue that further warming to 1.5°C would likely generate several metres of sea level rise over the coming centuries as the Greenland and Antarctic ice sheets melt in response to both warming air and ocean temperatures.

This would make it very difficult and far more expensive to adapt to rising sea levels, causing extensive loss and damage to coastal and island populations and leading to the widespread displacement of hundreds of millions of people.

Currently, around 230 million people live within one metre of sea level and melting ice represents an existential threat to those communities, including several low-lying nations.

The researchers add that further work is urgently needed to more precisely determine a “safe” temperature target to avoid rapid sea level rise from melting ice sheets.

Lead author Professor Chris Stokes said: “There is a growing body of evidence that 1.5 °C is too high for the ice sheets in Greenland and Antarctica. We’ve known for a long time that some sea level rise is inevitable over the next few decades to centuries, but recent observations of ice sheet loss are alarming, even under current climate conditions.

“Limiting warming to 1.5°C would be a major achievement and this should absolutely be our focus. However, even if this target is met or only temporarily exceeded, people need to be aware that sea level rise is likely to accelerate to rates that are very difficult to adapt to – rates of one centimetre per year are not out of the question within the lifetime of our young people.

“We are not necessarily saying that all is lost at 1.5°C, but we are saying that every fraction of a degree really matters for the ice sheets – and the sooner we can halt the warming the better, because this makes it far easier to return to safer levels further down the line.”