The Nansen Legacy

With the melting Arctic sea-ice cover, new areas open. At the center of these changes is the Barents Sea. The Nansen Legacy (2018-2024) aimed to understand the consequences of the sea-ice retreat for the ecosystem there and in the adjacent deep Arctic Ocean. This requires a holistic understanding of the interaction between the atmosphere, sea ice, ocean currents, and marine plants and animals. Therefore, the Nansen Legacy united more than 300 researchers from various natural science disciplines and from ten Norwegian research institutions. The project was a historically large initiative in Norway, crucial for ensuring a scientific basis for future sustainable management of Arctic marine areas. After six years, 21 scientific expeditions to the northern Barents Sea and the deep Arctic Basin are completed. Year-round field observations provided annual cycles and changes between years documenting the marine ecosystem and weather, ocean currents, and sea-ice conditions that affect it. Satellite and drone measurements provided data coverage with large geographical extent. The team mapped how the ecosystem is affected by human activities such as pollution, fisheries, and ocean acidification. New marine observation technology was tested, and the expeditions contributed to improved Arctic wave, weather, and sea-ice forecasts. Geological surveys place the current observations in a climate historical perspective. Numerical models were used to understand how the climate and ecosystem may develop in the future. A main finding is that the Barents Sea has been characterized by winter ice and Atlantic water since the last ice age, while our climate projections identify the area as the first Arctic shelf sea without winter ice in this century. The increasingly warmer Atlantic water is the main regulator of ice and ocean climate here, but with significant interannual variations. Wind and ice drift change sea-ice conditions at short notice. Heat transport with ocean currents through the Barents Sea and into the Polar Basin has increased, and the new ice-free sea areas absorb more CO2 than before. Ecosystem responses include changes in production, species spreading northward, and new food web connections. Changes also occur stepwise during marine heatwaves, that appear more frequently and last longer. The northern Barents Sea still has an Arctic ecosystem, but Arctic species are losing out to a more adaptable ecosystem where krill, capelin, and cod are long-term winners. The multiple stressors can amplify responses, and the future Barents Sea will become warmer and more acidic, driven by CO2 emission levels. Improved ecosystem models showed how the ecosystem historically has responded to overfishing and changes in ocean temperature, and provided future scenarios. Model studies combined with historical data showed that temperature increase affects stocks and food webs more than fisheries, but fisheries can amplify negative climate effects. Contaminant mapping of both polar cod, cod, and capelin showed low mercury levels, but far below the EU's limit values. New sensors on underwater robots provided better observations of both the Polar Front and microalgae under the sea ice. Coupling of wave and atmospheric models significantly improved the forecasting of strong winds and large waves. Better sea ice models showed how cracks in the ice created more leads and heat loss to the atmosphere, and 25-30% of Arctic sea ice is now produced in leads. New studies of storm tracks and weather conditions found no support for a direct connection between Arctic sea ice and winter weather further south in Europe. However, extreme precipitation on the west coast of Svalbard can be linked to reduced sea-ice cover on the East Greenland shelf. Environmental challenges, opportunities and results were actively communicated through various channels to the general public, youth, various interest groups for the northern areas, researchers, and decision-makers. Research blogs on Forskning.no and sciencenorway.no shared field activities, complemented by artists and journalists. Dialogue meetings, debates, and lectures nationally and abroad discussed climate and knowledge for management. Synthesis work, fact sheets, and a new book about the Barents Sea system document the larger picture and future scenarios for the climate and ecosystem. Outreach has largely occurred in collaboration with users. The results were highlighted in an international final symposium. Focus and competence building on data publication have been successful. A total of 128 early career researchers have been involved in the project. The Nansen Legacy represents a new type of research structure for large and challenging tasks. In the Nansen Legacy, the universities of Oslo, Bergen, Trondheim, and Tromsø, UNIS, IMR, NPI, and MET Norway, as well as NERSC and Akvaplan-niva, collaborated. The budget was 740 million NOK, with 50% in-kind from the institutions. https://arvenetternansen.com

The Nansen Legacy project team succeeded not only in reaching our research goals, but also in realizing our organizational potential for exploring large complex research challenges based on national collaboration. The Nansen Legacy integrated the involved researchers and research institutions for a common purpose, including the interaction with the larger research community and society. Impact The most obvious and direct impacts of the Nansen Legacy are the extensive research and new knowledge established on the Barents Sea and larger-scale impacts. Knowledge and practices was built and shared across generations, institutions and disciplines. The national pool of expertise and infrastructure was mobilized to explore the collectively identified research challenges. The pursuit of collective insights, sharing of colleagial competence, and joint access to logistic capabilities can serve as a model. The increased national collaboration is manifested through joint publications, with a larger share of international co-authors than the average for Arctic publications in Norway. The extensive collaborations extended networks, improved models and methodology, harmonized sampling protocols, new collaborations in research proposals, and new positions for many of the early career scientists. The focus on outreach and useful science, resulted in dedicated products like fact sheets on important findings, synthesis papers and a new book on the Barents Sea system. Being available for national stakeholders, including government ministries, was a priority. Legacy The Nansen Legacy offers a proof of concept for future national research priorities – an organizational model and environment of trust for tackling research challenges that require large-scale teamwork to succeed. The multi-disciplinarity and complementary approaches across institutions provided extended context to the explorations of the individual scientists as well as the research questions, and thus the broader understanding of the Barents Sea system and dynamics. The projections on the future Barents Sea provide opportunities for policy makers and management to take informed decisions on future activities and important actions. Prioritizing data sharing and training boosted competence and practices both of scientists and data management in all the involved institutions towards FAIR data handling. The interaction with management and user groups increased the awareness, enthusiasm and competence among both scientists and stakeholders for the importance and the challenges in making the Nansen Legacy science useful. With 128 early career scientists, a new generation of Norwegian polar researchers is established. Their successful integration in the research community, in the use of infrastructure and in societal interaction will guide and leave footprints in science and society in the decades to come. Trust and respect among the involved partners substantiated the collaboration throughout the project.

The Nansen Legacy is a joint, concrete and ambitious plan to follow Nansen?s example in exploring the Arctic. To establish a holistic understanding of a changing Arctic Ocean and ecosystem, the project will provide the scientific knowledge base needed for future sustainable resource management in the transitional Barents Sea and the adjacent Arctic Basin. An ice-free Arctic is gradually emerging. The winter sea ice retreat is to date most pronounced in the Barents Sea, the Atlantic gateway to the Arctic. As sea ice retreats and technology and infrastructure improves, it is imperative to rise to the scientific and exploratory legacy of Fridtjof Nansen and move poleward through the Barents Sea. The Norwegian Arctic research community, joint in the Nansen Legacy, will take on Nansen?s tasks with several approaches. First, through a number of multidisciplinary cruises, a holistic ?ground truth? will be established for the physical environment and the ecosystem in the northern Barents Sea, and adjacent Arctic Basin. Secondly, there will be an assessment on the impact of human activities in this region, with an emphasis upon ocean acidification, pollution and the impacts of fisheries. Thirdly, using scientific models, a 2020-2100 outlook for the expected state of climate, sea ice, and ecosystem will be provided. This include development of multi-perspective scenarios for the northern Barents Sea developed by scientists and users in a 2050 perspective. Fourthly, in order to improve safety for people and commercial operations, improved polar weather forecasts will be developed. Fifthly, to ensure open data availability in accordance with national and international standards, the Nansen Legacy will improve, secure and operationalize national data archives. At last, most importantly, the core aspect will be the emphasis on recruitment and training of the next generation of cross-disciplinary Arctic researchers, and on engaging and educating the public.