Science and society
From space, the Arctic sea ice cover appears as a white surface, retracting and extending with the seasons. Every year in September, it reaches its minimum area, which has been decreasing over the past decades. Yet the sea ice extent alone is an incomplete indicator of ongoing changes in the Arctic.
By: Kristina Baer // Arctic Council Secretariat, Sebastian Gerland // Norwegian Polar Institute and Rolf Rødven // Arctic Monitoring and Assessment Programme
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“We cannot determine the status of Arctic sea ice by only observing if a region is covered by ice or not. In satellite images from two consecutive years, the ice extent could look very similar, but this tells us nothing about the properties of the ice, how thick it is and how old,” says Sebastian Gerland, geophysicist and section leader at the Norwegian Polar Institute in Tromsø.
During their expeditions to Svalbard, the Barents Sea, and the Fram Strait, Gerland, and his colleagues have been collecting sea ice data for more than two decades. This time span has seen a substantial thinning of Arctic sea ice. “We increasingly find younger sea ice that has formed the same year. These young floes are more susceptible to different forcers. For example, they reflect less and absorb more solar radiation than older ice floes, and thus they are more likely to melt.”
These findings feed into Gerland’s scientific publications on sea ice – its thickness, optical properties, and snow cover (to just mention a few). But how do his and his collaborators’ findings about ice make their way to the public, and – more specifically – into the hands of those who are making decisions?
One way is through scientific assessments and their summaries for policymakers: compilations of state-of-the-art knowledge that – for example – reflect the current changes in the Arctic, including their impacts in and beyond the Arctic, identify knowledge gaps and formulate recommendations for action.
A landmark assessment for the Arctic was the 2005 Arctic Climate Impact Assessment (ACIA). The report was produced by the Arctic Monitoring and Assessment Programme, one of six Working Groups of the intergovernmental Arctic Council. Some 300 scientists, experts, and representatives for Indigenous peoples collaborated to develop a comprehensive, multidisciplinary account of climate change in the Arctic. The result is probably one of the most widely read documents focused specifically on the Arctic, and one of the world’s first in-depth regional accounts of climate change impacts.
ACIA was also Sebastian Gerland’s entry point to the work of the Arctic Monitoring and Assessment Programme (AMAP). “At that time I was working on the albedo feedback of sea ice – the processes ice triggers when it reflects sun rays. In 2003, we organised a workshop on Arctic climate feedback mechanisms as a contribution to ACIA, which is how I got more familiar with the ongoing assessment work.”
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Gerland became a member of AMAP’s climate expert group and was soon invited to join the work on a sea ice chapter for the subsequent climate assessment with a focus on the cryosphere: Snow, Water, Ice and Permafrost in the Arctic (SWIPA). The first SWIPA assessment was published in 2011 and reported, amongst other things, on the “thinning of the ice cover and loss of old ice types” and the ecological, social and economic impacts this had. A second, updated SWIPA report followed in 2017.
“Working on the SWIPA assessments was a highly rewarding experience,” says Gerland. “Cooperating with scientists from different countries and scientific disciplines opened my eyes to a larger context. I could see how my work on sea ice fitted into the bigger picture, how sea ice physics affected other systems and processes, and how thinning sea ice affected both people and the ecosystem.”
Together with over a hundred scientific experts nominated by their countries to contribute to the report, Gerland reviewed the best available knowledge on the Arctic cryosphere for the SWIPA 2017 assessment and synthesised it into 270 pages. This scientific exercise followed specific guidelines, as AMAP’s executive secretary Rolf Rødven explains: “The most important principle for AMAP assessments is that of scientific integrity. All reports are peer-reviewed to guarantee the scientific standard. But in addition, we make sure that our reports embrace the diversity of knowledge on the Arctic – also including Indigenous and local knowledge.”
In order to ensure that all relevant data have been considered and authors have not been biased, the review process starts with a national data check and ends with an examination by independent referees. The result of this process is a comprehensive scientific report, a summary of current scientific knowledge on Arctic change: a tome weighing more than a kilogramme. Arguably too dense – both literally and figuratively – for busy policymakers. So, how can they be reached?
“Based on this compiled knowledge, scientists develop a scientific summary which also is the basis for a set of policy recommendations. Both documents go into a brief summary for policymakers. The policy recommendations are sent to the national representatives of the Arctic states, who review and discuss the suggestions. When consensus is reached on the policy recommendations, this summary is ready to be presented,” explains Rødven.
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The final assessment and its summary are presented to ministerial-level representatives of the eight Arctic States. The Ministers of Foreign Affairs of these states met most recently in Rovaniemi, Finland, in May 2019. AMAP’s Arctic Climate Change Update 2019, which draws and builds on the SWIPA 2017 assessment, did not go unnoticed.
“On my way here, I read the [AMAP] Arctic Climate Change Update 2019, highlighting new findings,” said Margot Wallström, who at that time was Sweden’s Minister for Foreign Affairs.
“Annual air temperatures in 2014 to 2018 were all greater than any year since 1900. Sea ice volume in September [is] declining by 75 percent since 1979.” The Update provided a glimpse of knowledge based on hundreds of scientific publications – a glimpse that can make a difference.
Sebastian Gerland sums it up: “Assessments and their summaries trigger a process: people start to discuss topics, find out more about Arctic change, and pay attention to developments they might have been unaware of previously. Assessments and summaries build a foundation for knowledge-based decision-making and at the same time are a guide for future research.”