Ice in the Arctic staged a surprise revival in 2013, bucking the long-term trend of decline, according to the first analysis of the entire ice cap’s volume. The revival was the result of cooler temperatures that year and suggests that, if global warming was curbed, the Arctic might recover more rapidly than previously thought.

The shrinking Arctic ice cap is one of the best known impacts of climate change. The indication that it could be reversible is rare good news for a region where climate change has driven up temperatures far faster than the global average.

The extent of Arctic ice has shrunk by 40% since the late 1970s, when satellite measurements began. But getting comprehensive data on the thickness of the ice, rather than just its area, was difficult until the European Space Agency launched the Cryosat satellite in 2010.

The satellite’s 88 million measurements, analysed in Nature Geoscience, show that from 2010-12 the Arctic ice volume fell by 14%, in step with the warming trend of the last few decades. But in 2013, the ice volume jumped up by 41%.

Average thickness of Arctic sea ice in spring as measured by CryoSat-2 between 2010 and 2015. Photograph: CPOM/ESA

“It’s fair to say that none of us were really expecting that,” said Rachel Tilling, at University College London and who led the study. But she dismissed the idea of a wider recovery of the ice cap, saying that climate change is still driving average temperatures up, despite significant variation from one year to the next. “It was a cold year – that happens.”



In fact, while colder than recent years, the temperature in 2013 would have been regarded as normal as recently as the late 1990s. “This allowed thick sea ice to persist northwest of Greenland because there were fewer days when it could melt,” said Tilling.

The research is significant as it shows the Arctic ice cap may be more resilient than expected. Tilling said: “You see Arctic sea ice as dwindling and in decline, but then there is a cold year and you get some of the ice back. It shows there is hope for Arctic sea ice, if you can turn the clock back to colder temperatures, which would need huge reductions in carbon emissions.”

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In 2014, the melting trend continued with a fall of 6% in volume compared to 2013. The latest data on the extent of Arctic ice, from the US National Snow and Ice Data Center, shows that the cap in June was the third smallest recorded by satellite measurements. The NSIDC warned that: “Persistently warm conditions and increased melting late in June may have set the stage for rapid ice loss in the coming weeks.”

Scientists usually consider a few decades of data is required to assess climate trends. “You can’t look at the long term trend with only five years of data, which is why we can’t talk about an Arctic recovery,” said Tilling.

She is concerned that Cryosat-2 data collection is set to stop after just seven years: “We need Arctic-wide thickness measurements of the ice, but Cryosat is only commissioned until 2017.”

Co-author Professor Andy Shepherd, also at UCL said: “Understanding what controls the amount of Arctic sea ice takes us one step closer to making reliable predictions of how long it will last, which is important because it is a key component of Earth’s climate system.”