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Ice-free Arctic Projections under the Paris Agreement

From rising global sea levels to a depletion of fisheries to accelerating the trend of global warming worldwide, the impacts of rising Arctic temperatures extend to those living far south of the Arctic Circle.

 New research by Environment and Climate Change Canada (ECCC) scientists Michael Sigmond, John C. Fyfe, and Neil C. Swart, published last month in Nature, sheds new light on the implications of global temperature rise. Their work shows how seemingly small increases in the average global temperature could have a profound impact on the extent of Arctic sea ice and as a result, life both in the Arctic and worldwide.

The Paris Climate Agreement agrees to keep the average global temperature rise to less than 2°C above pre-industrial levels, while pursuing efforts to limit the increase to 1.5°C. While the 0.5°C difference may seem small, the researchers’ projections suggest that a rise in average global temperature from 1.5°C to 2°C could result in an eightfold increase in the frequency of ice-free conditions in the North in summer.

New research shows that small increases in the average global temperature could have a profound impact on the extent of Arctic sea ice

New research shows that small increases in the average global temperature could have a profound impact on the extent of Arctic sea ice

According to the study, ice-free conditions in summer would occur once every 40 years with a 1.5°C rise in the global temperature, as opposed to once every five years with a temperature rise of 2°C. The results of the study emphasize the implications of nations’ success in meeting the Paris Agreement, as limiting global warming to 1.5°C, or even 2°C may be too high to ensure year-round sea ice in the North.

Previous work has concluded that an ice-free Arctic in summer would be unlikely at 1.5°C, and that there was only about a one in three chance with warming of 2°C. However, the authors note that these findings only apply to “the time period prior to reaching the warming levels.” The extent of Arctic sea ice, however, is expected to fluctuate significantly even after global temperatures stabilize. As a result of these authors taking into account these fluctuations, the probability of an ice-free Arctic increases substantially.

The study also notes that if average global warming rises to 3°C, which is expected to occur by 2100 if countries only pursue current emission reduction policies, ice-free conditions would occur in the Arctic every summer.

“We have to increase our commitments to reduce emissions if we want to avoid such a scenario,” Sigmond emphasizes.

A widespread loss of sea-ice would have a profound effect on life in the Arctic, since sea ice is a critical element in terrestrial and marine food chains. Sigmond notes that local communities also rely on sea ice for many facets of their life – hunting, travelling, and a variety of other activities.

He also stresses that it is not only northern communities that would be affected.

ECCC scientists Neil C. Swart, Michael Sigmond, and John C. Fyfe

ECCC scientists Neil C. Swart, Michael Sigmond, and John C. Fyfe

“What happens in the Arctic does not stay in the Arctic … this is a global issue” Sigmond says. Less sea ice in the Arctic causes the ocean to absorb more solar radiation, affect ocean circulation and weather, and causes global sea levels to rise.

The research shows that ice-free summers are expected to be rare at 1.5°C warming (1 in 40), more frequent under 2.0°C warming (1 in 5) and are likely to occur every year if nations do not increase their commitments to support the Paris Agreement, thus providing an important policy driver for action at the international level.

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