O Arctic sea ice sheet has a clear seasonal cycle: it increases during autumn and winter and decreases during spring and summer. The ice surface minimum is reached in late summer. For this reason, an international group of researchers focused on this period to determine that this icy region could stop being icy during the month of September as early as the 2030s, even in a low emissions scenario. This would mean anticipating what was previously planned by almost a decade.
The authors of this work, published in Nature Communications, they highlight the impact of human activities on the Arctic and demonstrate the importance of planning for and adapting to a seasonally ice-free Arctic for the foreseeable future.
“Warming in this region will accelerate, which could increase the extreme weather events in northern mid-latitude areas, such as heat waves and wildfires. This melting does not directly affect sea level rise, but could increase it due to accelerated melting of the Greenland ice sheet,” he told SINC. Seung Ki Minresearcher at Pohang University of Science and Technology (South Korea) who leads the study.
An Arctic without sea ice affects humans and natural ecosystems within and beyond this area. For example, it produces changes in marine activity, further accelerating warming and change the carbon cycle.
It will likely increase the military importance of this region, given the short sea lanes that link northern Europe, North America and Russia in this area.
“The loss of summer sea ice in the Arctic Ocean is likely to increase its use for shipping and other economic activities. Furthermore, in light of current tensions, it will likely increase the military importance of this regiongiven the short maritime routes that connect northern Europe, North America and Russia in this area”, guarantees SINC Dirk Notzco-author of the study from the University of Hamburg (Germany).
An underestimated melt rate
To analyze the human contribution to ice decline and project future predictions, Min’s team used observational data between 1979 and 2019 to constrain climate model simulations. The results suggest that the anthropic impact can be observed throughout the year and is largely attributed to the increase in Greenhouse gas emissions. Contributions from aerosols and natural factors (such as solar and volcanic activity) are much smaller.
This new work predicts that the Arctic could run out of sea ice by September 2030 to 2050 under all emissions scenarios. This contrasts with previous assessments discussed in the IPCC Sixth Assessment Report, which did not predict a summer ice-free Arctic with low emissions.
The Korean expert. who participated in the elaboration of the cryosphere chapter of the latest IPCC report, emphasizes that they then wrote: “The Arctic is likely to be without sea ice before 2050 under all scenarios considered.” This conclusion, he continues, “is different from that of Chapter 4, which focused on climate model simulations, because we still use additional methods to conceptually correct for biases in model simulations.”
They used the same IPCC models but adjusted future simulations and found that they underestimated the fusion rate, so they scaled up the model projections. “When we wrote the report, we knew that the models generally lost ice more slowly than observed, so we already felt that the respective results derived directly from the models were quite conservative. In the IPCC chapter on the cryosphere, we made a slightly bolder claim, using simpler conceptual methods,” he continues.
Inevitable, yes, but the impact must be reduced
Scientists have been warning about this disappearance for many decades, “it is sad to see that these warnings were largely ignored, with the consequences we now face. Hopefully this first ‘too late’ can be heard by policymakers so that we can at least protect other components of our climate system by limiting the future as much as possible. global warming”, points out Notz.
Bear in mind that, in the case of Arctic sea ice, future emissions will continue to have a significant impact: with more emissions, we will have an ice-free Arctic Ocean more often and for longer and longer periods. “Although we cannot prevent the loss of sea ice in the summer in a few years, we can make the ice disappear every summer”, says the researcher from the German university.
It is already too late to continue protecting Arctic sea ice in summer: it will be the first major component of our climate system that we will lose through our emissions
The low emissions scenario considered in this study is equivalent to the 2°C warming target of the Paris Agreement. This means we can avoid an arctic without ice in summer if we reduce CO emissionstwo more aggressively, following the path to reach 1.5 degrees, that is, net zero emissions by 2050.
“We expect substantial ecosystem changes for all species whose habitat depends on the existence of sea ice throughout the year. Even a single ice-free summer can cause substantial disturbances. Polar bears, for example, could face short periods of absence of ice in the Arctic Ocean, withdrawing to land areas and adapting, in a way, to the food sources available there”, says the scientist.
Melting sea ice will also warm the Arctic region, and warmer polar conditions will affect species that live in high northern latitudes, such as Arctic foxes and reindeer.
“Our new findings mean that it is already too late to continue protecting Arctic summer sea ice as a landscape and as a habitat: it will be the first major component of our climate system that we will lose with our greenhouse gas emissions”, concludes Min.
Yeon-Hee Kim et al. “Constrained observation projections of an ice-free Arctic, even under a low-emissions scenario”, Nature Communications.