New research shows Arctic could see ice-free summers by 2030

New research has moved up the time by which the Arctic Ocean ispredicted to be free of summer ice.

A paper published Tuesday in the journal Nature has concludedthat those northern waters could be open for months at a time asearly as 2030, even if humanity manages to drastically scale backits greenhouse gas emissions.

"It brings it about a decade sooner," said Nathan Gillett, anEnvironment and Climate Change Canada scientist and one of theco-authors of the study.

Gillett and his colleagues had noticed the growing differencesbetween what climate models say should be happening to sea ice andwhat's actually going on.

"The models, on average, underestimate sea ice decline comparedwith observations," Gillett said.

'Scaling up' greenhouse gas effects

The researcherswanted to know how much they'd have to tweak the model tomake it fit the data and what those tweaks might reveal if theywere projected into the future.

To do so, the scientists first teased out the effect ofgreenhouse gases from other factors that affect sea ice loss, such as artificial chemicals from aerosols or natural events such asvolcanic eruptions. The impact of aerosols was found tobenegligible and the study concluded that natural events contributedno more than 10 per cent of sea ice loss.

With greenhouse gases isolated as the main culprit, they thenlooked at how those emissions were used in their climate model. By"scaling up" the effect of greenhouse gases, the researchersachieved a much better fit with satellite images of ice cover.

That more accurate assessment of the influence of greenhousesturned out to come with a warning.

Previous estimates had suggested that Arctic summer sea icewouldn't disappear until the 2040s at the earliest. If humanitymanaged to bring its emissions down, year-round sea ice might evensurvive.

But once the model had been brought in line with what was happening on the water, predictions of summer ice disappearance gota lot closer.

"The range is then 2030 to 2050," Gillett said. "And evenunder the lowest emission scenario, with the scaling the Arctic isice-free."

Summer ice 'extremely likely' to disappear

Nothing is certain, Gillett cautions. But this is close.

"I would say it's extremely likely."

That would mean that by the end of the melt season in September,the Arctic would have less than one million square kilometres of seaice, even under low emissions. If emissions remain high, thatice-free period could last months.

The average ice extent for April 2023 was 14 million squarekilometres.

As well, the study is the first to measure sea ice trends forevery month of the year. Previous studies have focused on the summermonths.

By comparing ice extent year-over-year February 2019 againstFebruary 2018, for example the data showed ice loss from climatechange in every month of the year.

'More sensitive than we thought'

Pam Pearson of the International Cryosphere Climate Initiative, anetwork of policy experts and researchers, has seen the Nature studyand said it's strong evidence that greenhouse gases are changing theArctic faster than previously thought.

"More ice is being lost, faster than even the most recent modelspredict," she wrote in an email.

"Observations today outpace even high-end predictions. Globalice stores simply are more sensitive than we thought to slight changes in warming."

Gillett said an ice-free Arctic would certainly hasten thewarming of lands around the waters already warming at three timesthe global average. The fragile ecosystem that depends on sea ice home to everything from algae to polar bears would change utterly.

And when it comes to climate, what happens in the Arctic may notstay in the Arctic.

"People have looked at the possible implications of Arcticwarming on the climate at lower latitudes," Gillett. "That's still a topic of debate."