Humans to blame for bulk of Arctic sea ice loss: study

March 13, 2017
Man-made warming is mainly to blame for the loss of Arctic sea, a new study says. The loss has far-reaching impacts on polar bears and other Arctic species

Natural changes in the environment are responsible for about 40 percent of Arctic sea ice loss, while humans are to blame for the rest, a climate study said Monday.

The paper, based on model simulations of different climate conditions, was a rare attempt to quantify the relative contributions of humans and Nature to the dramatic decline and could have a major impact on future research into Arctic ice lost.

Understanding all causes of the sea ice retreat is crucial for accurately projecting the rate of future loss, and trying to slow it.

Scientists have long accepted that natural changes in the environment, such as atmospheric air circulation, were at least partly responsible.

But its relative contribution, and that of human-induced global warming, has been fiercely debate.

The new study concluded that up to 60 percent of sea ice decline since 1979 was caused by summertime changes in atmospheric circulation.

About 70 percent of the air flow changes, in turn, were the result of natural variability, not human-caused .

Taken together, this meant that between half and two-thirds the sea ice decline was attributable to climate change, said the American team.

Natural variability, on the other hand, "dominates the Arctic summer circulation trend and may be responsible for about 30-50 percent of the overall decline in September sea ice since 1979," they said.

Commentators not involved in the study said its findings do not call into question whether human-induced planet warming has contributed to Arctic .

'Not good news'

"Realising that humans have caused 50-70 percent of the decline is not good news," said Twila Moon, a lecturer in Cryospheric Sciences at the University of Bristol.

"Continuing to put carbon dioxide and other emissions into the atmosphere is having a direct negative impact on the Arctic, including sea ice," she said via the Science Media Centre in London.

Chris Rapley, a professor of climate science at University College London, said the study helped explain why Arctic sea ice was disappearing faster than most climate models predict—they underestimated the contribution of natural drivers.

Models for future predictions will have to be adapted, according to the findings published in the journal Nature Climate Change.

Last month, US government scientists said Arctic sea ice cover in January was 1.26 million square kilometres (487,000 square miles)—8.6 percent below the 1981–2010 average.

This was the smallest January extent since records began in 1979 and 100,000 square miles smaller than the previous low recorded in 2016.

Sea ice, floating slabs of frozen ocean water which grow in winter and melt in summer, provides an essential platform for hunters—humans and bears alike—and helps moderate the by reflecting the Sun's rays.

The region is warming at about twice the global average rate.

Explore further: Is Arctic sea ice doomed to disappear?

More information: Nature Climate Change,

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1.4 / 5 (10) Mar 14, 2017
Who would be foolish enough to trust a climate model?
1 / 5 (6) Mar 14, 2017
I'm wondering how the authors of this study so confidently attribute the ice melt to "human-induced global warming." There's a huge debate going on as to the extent that fossil fuel emissions have contributed to the relatively small amount of global warming we've seen over the past 100 years or so. In certain circles most of the warming is assumed to be due to human activities, but that's been contested by many, including some noted climate scientists. Does this mean they've managed to convincingly refute the skeptics? Or is that an assumption, built in to their argument ahead of time.
1 / 5 (2) Mar 15, 2017
Humans to blame for bulk of Arctic sea ice loss: study
Other media present the same result a bit differently...
5 / 5 (4) Mar 15, 2017
There's a huge debate going on as to the extent that fossil fuel emissions have contributed to the relatively small amount of global warming

I dunno where you see this 'huge debate'. Climate scientists seem to be pretty unanimous in this. anyone else 'debating' this is like children debating on the cause of a particular patient's cancer. They can debate loudly - but that doesn't make their 'debate' any more meaningful than random noise.

Does this mean they've managed to convincingly refute the skeptics?

Any left? I mean any that actually know anything about climate science?

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