Arctic could be nearly ice-free within 50 years: study

TORONTO -- As the United Nations sounds the alarm about an impending climate disaster unless immediate action is taken to reduce fossil fuel emissions, a new study warns the Arctic Ocean will be essentially ice-free within the next 50 years.

According to researchers from the University of California, the Arctic Ocean will be nearly ice-free for part of each year beginning sometime between 2044 and 2067 if current global carbon emissions remain unchanged.

Historically, when Arctic ice melts to its lowest amount each September, it covered about six million square kilometres. But over the last decade, that number has decreased to closer to four and a half million. The research, published in the journal Nature Climate Change, warns that the new low-point could be one million square kilometres and mostly focused around what scientists consider “resilient” coastal regions of Greenland and in the Arctic archipelago. The open water of the Arctic Ocean would be virtually ice free.

Climate scientists consider the one million marker a “tipping point.”

“It’s almost at a point of no return or very slow return,” said the study’s leader author Chad Thackeray, an assistant researcher at the UCLA Institute of the Environment and Sustainability’s Center for Climate Science, in an interview with CTVNews.ca.

“Once you lose that much ice cover, the ocean begins to take up much more heat than it normally would by absorbing more solar radiation. Essentially this warms the ocean which promotes even more melt. It becomes a sort of runaway cycle until you have no ice left. Once we’re below that threshold it’s very hard for ice to regrow and would take a substantial amount of time.”

While scientists have been attempting to predict the timeline for declining sea ice for years, projections have widely varied with some models calculating an ice-free future for the Arctic Ocean as early as 2026 and others suggesting it won’t occur until as late as 2132. The new study’s identification of 2044 confirms some earlier timeline predictions, said Walt Meier, a senior research scientist at the National Snow and Ice Data Center.

“We’ve seen some projections that were that soon before, but the study narrows things down … so we have more confidence in that number than we had before,” he said on CTV News Channel on Tuesday.

One of the reasons predictions diverge so much is their understanding of a process called “sea ice albedo feedback.” This is a cycle that occurs when a patch of ice melts and the surface of the water is exposed to sunlight. Because the dark water is less reflective than ice, it absorbs the sun’s heat, which results in greater local warming. This increased warming, in turn, causes further ice melt in the area. This positive feedback loop is one of the reasons why the Arctic is heating up twice as fast as the rest of the globe, according to scientists.

In an effort to provide some clarity about the effects of sea ice albedo feedback in these climate projections, researchers assessed 23 global climate models depicting seasonal melt from the past 30 years and compared them with satellite observations.

The six models that most accurately predicted the actual historical results were kept for the study, while the ones that missed the mark were discarded. By eliminating those models, the researchers were able to narrow the range of predictions for ice-free Septembers in the Arctic sea.

“The trajectory we’re on, we’re going to melt ice much faster than if we were taking significant emissions cuts,” said Meier. “The Arctic is going to become a much warmer place and that has a lot of impacts of course in the Arctic on the wildlife, polar bears, people living in the Arctic communities, there’s going to be more storms, more coastal erosion, but also, globally, the Arctic is interconnected with the rest of the globe so changes in Arctic climate are going to have big effects, potentially, on lower latitudes in the rest of the globe.”