‘No statistically significant decline’: Arctic sea ice loss dramatically slows since 2005
Scientists say a dramatic slowdown in Arctic sea ice loss over the past 20 years is “surprising” but consistent with global warming trends.
A dramatic slowdown in Arctic sea ice loss over the past 20 years has been observed by scientists, who say the finding “may sound surprising” but is consistent with human-induced global warming trends.
Researchers from the University of Exeter, in a study published this month in the journal Geophysical Research Letters, analysed Arctic sea ice cover using two different datasets of satellite measurements, from 1979 to the present.
“Over the past two decades, Arctic sea ice loss has slowed considerably, with no statistically significant decline in September sea ice area since 2005,” they wrote.
“This pause is robust across observational data sets, metrics, and seasons.”
Focusing on September, when sea ice cover is at its minimum, they found sea ice declined by 0.35 and 0.29 million square kilometres per decade between 2005 and 2024.
Compared with the longer-term rate of decline since 1979 of 0.78 to 0.79 million square kilometres per decade, that marked a 55 per cent to 63 per cent slowdown.
The 20-year period was the slowest rate of sea ice loss since records began, and four to five times slower than the peak 20-year period of 1993 to 2012.
The researchers said the findings were consistent with climate models that show pauses in sea ice loss across multiple decades can happen, offset by “natural climate variations” even as greenhouse gas emissions continue to rise.
Climate models suggest the chances of such a slowdown were about 20 per cent.
Comparing the current slowdown to similar pauses in model simulations, “we see that it could plausibly continue for another five to 10 years, although the same slowdown makes a faster-than-average sea ice decline more likely in the coming years”, they wrote.
“Summer sea ice conditions in the Arctic are at least 33 per cent lower than they were at the beginning of the satellite record nearly 50 years ago,” Dr Mark England, who led the study while at the University of Exeter and is now at UC Irvine, said in a statement.
“Given this — and the indisputable fact of human-driven climate change — it may seem surprising to find a temporary slowdown in Arctic sea ice loss.
“It is, however, entirely consistent with climate model simulations and is likely due to natural climate variability superimposed on the human-driven long-term trend. This is only a ‘temporary reprieve’ and before long the rate of sea ice decline will catch up with the longer term rate of sea ice loss.
“It’s like the analogy of a ball bouncing down a hill where the hill is climate change, given by Professor Ed Hawkins. The ball continues going down the hill but as it meets obstacles in its path, the ball can temporarily fly upwards or sideways and not seem to be travelling down at all — that trajectory is not always smooth but we know that at some point the ball will careen towards the bottom of the hill.”
When the current slowdown ends, climate modelling suggests the rate of sea ice loss could accelerate to 0.6 million square kilometres per decade faster than the longer-term trend.
The researchers estimate that the current pause has a nearly one in two chance of lasting another five years, and a 25 per cent chance of lasting another 10 years.
While most of the evidence from climate models suggest natural climate variations had played a large part in slowing the “human-driven loss of sea ice”, the modelling was inconclusive whether “changes in the human influence on climate (the ‘forced response’) have also contributed”.
“Overall, while it may sound surprising that Arctic sea ice loss has slowed down even as global temperatures hit record highs, the climate modelling evidence suggests we should expect periods like this to occur somewhat frequently,” they wrote.
It comes as a separate study from researchers at UNSW Sydney and the ANU, published today in the journal Nature, warns of “catastrophic consequences” for Antarctica unless urgent actions are taken to cut global carbon emissions.
“Rapid change has already been detected across Antarctica’s ice, oceans and ecosystems — and this is set to worsen with every fraction of a degree of global warming,” said lead author Dr Nerilie Abram, chief scientist at the Australian Antarctic Division (AAD).
Dr Abram said the sudden loss of sea ice in the region has a range of knock-on effects.
“This includes making the floating ice shelves around Antarctica more susceptible to wave-driven collapse,” she said.
She warned the West Antarctic Ice Sheet (WAIS) was at severe risk of collapse as global carbon dioxide levels continue to rise. This loss would raise sea levels by more than three metres, threatening coastal cities and communities worldwide.
“Such a collapse would result in catastrophic consequences for generations to come,” she said.
Originally published as ‘No statistically significant decline’: Arctic sea ice loss dramatically slows since 2005
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