Nature’s melting the Arctic as fast as man

‘Could see a recovery of sea ice’

NATURE could be as much to blame for the Arctic ice cap shrinking as man-made global warming, scientists say.

‘Random and chaotic’ changes in atmospheric circulation – the movement of air currents by which heat is distributed around the planet– are partly responsible for a gradual warming of the Arctic dating back decades, a study found.

While the researchers said humans are also to blame, their findings mean that if the natural conditions shift again Arctic ice could melt less quickly. However, it is still feared the Arctic will soon be ice-free during summer.

The US team said natural influences on the Arctic’s climate ‘may be responsible for about 30 to 50 per cent of the overall decline in September sea ice since 1979’.

Their study, which aimed to distinguish between man-made and natural influences, said the natural warming of the Arctic region may be tied to changes taking place as far away as the Pacific Ocean.

Lead author Qinghua Ding, an assistant professor at the Earth Research Institute, part of the University of California, Santa Barbara, said: ‘If this natural mode would stop or reverse in the near future, we would see a slow-down of the recent fast melting trend, or even a recovery of sea ice.’

But he said that in the long term, the build-up of man-made greenhouse gases will become an ever more overwhelming factor.

Sea ice hit a record low in summer 2012, satellite records since 1979 show. The ice is currently around its smallest level for midMarch, rivalling winter lows set in 2016 and 2015.

Loss of sea ice is expected to have numerous effects on the planet, including putting animals such as polar bears and seals at risk as their habitat shrinks.

It could also accelerate global warming and change climate pat- terns. This is because ice reflects sunlight back into space, so less ice would mean the ocean would absorb more of the sun’s heat and become warmer.

Ed Hawkins, an associate professor in meteorology at the University of Reading, who was not involved in the study, said: ‘Recent summer Arctic sea ice extents have all been amongst the lowest on record but this is not necessarily all due to warming global temperatures – part of the sea ice decline is also because of changes in the atmospheric circulation.

‘ Looking ahead, it is still a matter of when, rather than if, the Arctic will become ice-free in summer.’

Andrew Shepherd, professor of earth observation at Leeds University, praised the US study, published in the journal Nature Climate Change, for estimating the relative shares of natural and man-made influences on Arctic ice. ‘Nobody’s done this attribution before,’ he said.

In 2013, a panel of UN climate experts merely said human influences had ‘very likely contributed’ to the loss of Arctic ice, without estimating how much.