Ice-free Arctic summers now very likely even with climate action

https://www.theguardian.com/world/2020/apr/21/ice-free-arctic-summers-now-very-likely-even-with-climate-action

Damian Carrington Environment editor
Tue 21 Apr 2020 07.00 EDT


The loss of summer sea ice in the Arctic is now very likely before 2050, new research shows, even if the carbon emissions driving the climate crisis are cut rapidly.

The result has alarmed scientists but they said slashing greenhouse gases remained vital as this would determine whether Arctic summer ice vanished permanently or could recover over time. If emissions remain very high, there is a risk the Arctic could be ice-free even in the dark, cold winter months, a possibility described as “catastrophic”.

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Since satellite records began in 1979, summer Arctic ice has lost 40% of its area and up to 70% of its volume, making it one of the clearest signs of human-caused global heating. In 2019, it shrank to its second lowest extent on record.

The loss of the ice exposes the dark ocean, which absorbs more of the sun’s heat and further ramps up temperatures. These changes are also being increasingly linked to more extreme weather including severe winters, deadly summer heatwaves and torrential floods at lower latitudes such as in Europe and the US.

“Alarmingly the models repeatedly show the potential for ice-free summers in the Arctic Ocean before 2050, almost irrespective of the measures taken to mitigate the effects of climate change,” said Ed Blockley, who leads the UK Met Office’s polar climate programme and was one of the team behind the new research. “The signal is there in all possible futures. This was unexpected and is extremely worrying.”

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The models are not perfect and struggle to match closely the ice loss and global warming seen in historical data. “There is still a lot of uncertainty,” Blockley said. “But all the models are clear that the sea ice will continue to decline. At some point, it will be gone, but when that happens is still uncertain.”

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Prof James Screen, at the University of Exeter, UK, said: “It is important to keep in mind that although we might see an ice-free Arctic in all scenarios by 2050, the expected frequency of ice-free summers differs between scenarios. Under a higher emissions scenarios there may be ice-free summers every year, but in lower emissions scenarios they might be occasional.”

Blockley said the new research showed cutting carbon emissions remained vital to prevent the worst impacts on the Arctic, adding: “We are showing there is still hope.”