Geir Ottersen

• Ni, Yuanming; Bogstad, Bjarte; Ottersen, Geir; Sandø, Anne Britt; Årthun, Marius & Kvamsdal, Sturla Furunes (2026). Predicting Barents Sea Cod Stock Dynamics Using Oceanographic Data and Neural Network Analysis. Fisheries Oceanography. ISSN 1054-6006. 35(5), p. 665–676. doi: 10.1111/fog.70044. Full text in Research Archive Show summary

  Fluctuations in fish populations are driven by recruitment, growth, and mortality—processes heavily influenced by environmental variability, particularly in highly dynamic marine ecosystems such as the Barents Sea. The complex, nonlinear relationships between various environmental drivers and fish stock dynamics remain challenging to capture. Building upon earlier works that predict Barents Sea cod total stock biomass using lagged hydrographic variables, we combine a wide range of updated data and machine learning techniques to improve predictions. Specifically, we employ neural networks, which excel at modeling intricate, nonlinear patterns, using hydrographic variables and fishing mortality as inputs. Our results highlight the potential of machine learning to complement conventional methods, such as linear regression models, in fisheries science, providing more accurate predictions of stock biomass in response to environmental and anthropogenic pressures.

• Johannesen, Edda; Ottersen, Geir; Berg, Florian; Bogstad, Bjarte; Dalpadado, Padmini & Denechaud, Côme [Show all 17 contributors for this article] (2026). The Abrupt and Persistent Decline in Recruitment Success in Northeast Arctic Cod: A Review of Probable Causes. Fish and Fisheries. ISSN 1467-2960. doi: 10.1111/faf.70074. Full text in Research Archive Show summary

  Most of the previously large cod stocks in the North Atlantic are depleted to very low levels. A notable exception has been the Northeast Arctic cod inhabiting the Barents Sea. This cod stock reached a record high level around 2013, but since then has declined sharply, with older fish being fished out and few new recruits entering the stock. More specifically, since 2006 the average recruitment at age 3 per unit spawning stock biomass has dropped to a very low level. Here we review recent literature and data to evaluate potential causes of poor recruitment. We find that in most years the large spawning stock was successful in producing offspring up to the 0-group stage, but the survival thereafter was reduced—leading to few recruits into the fishable stock. Evidence points to consequences of northwards shifts of spawning locations, reduced inflow of Calanus and density dependent factors influencing pre-recruit survival at times when the spawning stock was at a record high level. However, large uncertainties in the causes of recruitment failure remain at a time when the Barents Sea ecosystem is experiencing unprecedented warming. A precautionary measure to avoid further decline and potential stock collapse in the current situation is to lower fishing pressure and improve management by setting reference points based on the recent period with low productivity. Including demographic characteristics like age diversity as explicit management targets to ensure spatial and temporal spread in spawning should be a goal for future method development.

• Langangen, Øystein Ole Gahr; Olsen, Tora; Ottersen, Geir; Eriksen, Elena & Durant, Joël M. (2025). Consequences of climate-related poleward shifts in cod spawning. Canadian Journal of Fisheries and Aquatic Sciences. ISSN 0706-652X. 82, p. 1–11. doi: 10.1139/cjfas-2024-0380. Full text in Research Archive Show summary

  With climate change, many species alter their distribution according to local climate velocities. For marine fish, suitable areas for spawning in a warming climate may be less favorable for the resulting offspring, e.g., the sensitive larval and juvenile phases. The size of the young-of-the-year before their first winter is an important factor for subsequent survival, year class formation, and population dynamics of many fish species and populations. Here, we investigate how the change in spawning location of the Barents Sea population of Atlantic cod ( Gadus morhua) may affect the mean individual size of the offspring in their first fall. We demonstrate how the observed climate warming-related northerly shift in spawning location may lead to smaller sizes of young-of-the-year cod. Our analysis reveals a positive effect of sea temperature on offspring size and a nonlinear effect of spawning stock biomass (SSB) with smaller offspring size at both the high and low end of SSB. Decreased offspring size is likely to affect population dynamics through reduced recruitment success, and we hypothesize that it may have been part of the reason for this population's recent reduction in biomass.

• Koseki, Mariko; Sandø, Anne Britt; Ottersen, Geir; Årthun, Marius & Stiansen, Jan Erik (2025). Exploration of short-term predictions and long-term projections of Barents Sea cod biomass using statistical methods on data from dynamical models. PLOS ONE. 20(7), p. 1–28. doi: 10.1371/journal.pone.0328762. Full text in Research Archive Show summary

  This study aims to explore how well simple statistical modeling can generate short-term predictions and long-term projections of the total biomass of the Northeast Arctic stock of Atlantic cod (Gadus Morhua) inhabiting the Barents Sea. We examine the predictability of statistical models only based on hydrographic and lower trophic level biological variables from dynamical modeling. Simple and multiple linear regression models are developed based on gridded variables from the regional ocean model NEMO-NAA10km and the ecosystem model NORWECOM.E2E. This includes the essential environmental variables temperature, salinity, sea ice concentration, primary production and secondary production. The regression models are statistically evaluated to find variables that can capture variability in Barents Sea cod biomass. Finally, future total cod stock biomass is projected by applying the best found regression models to the range of downscaled IPCC climate scenarios from the coupled Intercomparison Project Phase 6 (CMIP6 Shared Socioeconomic Pathways; SSP1–2.6, SSP2–4.5, SSP5–8.5). Our prediction models are based on variables that affect cod both directly and indirectly. We find that several regression models have high prediction skill and capture the variations in total stock biomass of the Northeast Arctic cod well. Our results suggest that increased ocean temperature and abundant zooplankton may lead to a large cod stock. However, even if total stock biomass has a positive trend with an increase in copepods in the highest warming scenario SSP5–8.5, we found that it has a negative trend in the low emission scenario SSP1–2.6 when the regional ocean and ecosystem models show weak cooling and reduced zooplankton. We show that variability in essential environmental variables can provide a remarkably good first approximation to cod dynamics. However, to resolve the full picture other factors like fishing and natural mortality also need to be addressed explicitly.

• Hansen, Cecilie; Hjøllo, Solfrid Sætre; Skogen, Morten D.; Mousing, Erik Askov; Skern-Mauritzen, Mette & Howell, Daniel [Show all 8 contributors for this article] (2024). The combined effects of warming, ocean acidification, and fishing on the northeast Atlantic cod (Gadus morhua) in the Barents Sea. ICES Journal of Marine Science. ISSN 1054-3139. 81(5), p. 877–886. doi: 10.1093/icesjms/fsae042. Full text in Research Archive Show summary

  With a biomass of ∼4 million tonnes, and annual catches of 900 000 tonnes, the northeast Atlantic (NEA) cod stock in the Barents Sea is the world’s largest. Scientists have been trying to explain the variability in recruitment of this stock for over 100 years, in particular connecting it to spawning stock biomass and environmental factors such as temperature. It has been suggested that the combination of ocean acidification and global warming will lead to a significant decrease in the spawning stock biomass and an eventual (end of this century) collapse of the NEA cod stock in the Barents Sea. We show that a temperature- and OA-driven decline in recruits will likely lead to a smaller cod stock, but not to a collapse. Instead, the level of fishing pressure and, not least, the choice of the recruitment function applied in simulations and how it relates to temperature, is extremely important when making such forecasts. Applying a non-linear relationship between temperature and spawning stock biomass—as has been done in studies that predict a collapse of the NEA cod stock—does not improve accuracy and, in addition, adds a large decrease in number of recruits that is not biologically supported.

• Kjesbu, Olav Sigurd; Alix, Maud; Sandø, Anne Britt; Strand, Espen; Wright, Peter J. & Johns, David G. [Show all 17 contributors for this article] (2023). Latitudinally distinct stocks of Atlantic cod face fundamentally different biophysical challenges under on-going climate change. Fish and Fisheries. ISSN 1467-2960. 24, p. 297–320. doi: 10.1111/faf.12728. Full text in Research Archive Show summary

  The reproductive success of marine ectotherms is especially vulnerable in warming oceans due to alterations in adult physiology, as well as embryonic and larval survival prospects. These vital responses may, however, differ considerably across the species' geographical distribution. Here we investigated the life history, focusing on reproductive ecology, of three spatially distant populations (stocks) of Atlantic cod (Gadus morhua, Gadidae) (50–80° N), in the Irish/Celtic Seas-English Channel Complex, North and Barents Seas, under past and projected climate. First, experimental tracking of spawning behaviour evidenced that the ovulation cycle is highly distressed at ≥9.6 (±0.25)°C (Tup). This knife-edge threshold resulted in erratic spawning frequencies, whereas vitellogenin sequestration remained unaffected, indicating endocrine rather than aerobic scope constraints. Cod in the Celtic Sea-English Channel are, therefore, expected to show critical stock depensation over the next decades as spawning grounds warm above Tup, with Irish Sea cod subsequently at risk. Second, in the relatively cooler North Sea, the northward retraction of Calanus finmarchicus (Calanidae) and Para-Pseudocalanus spp. (Clausocalanidae) (1958–2017) limit cod larvae feeding opportunities, particularly in the southernmost subarea. However, the contrasting increase in Calanus helgolandicus (Calanidae) does not counteract this negative effect, likely because cod larvae hatch ahead of its abundance peaks. Overfishing again comes as a twin effect. Third, in the still relatively cold Barents Sea, the sustainably harvested cod benefit from improved food conditions in the recent ice-free polar region but at the energetic cost of lengthier and faster spawning migrations. Consequently, under climate change local stocks are stressed by different mechanistic factors of varying management severity.

• Myksvoll, Mari Skuggedal; Sandø, Anne Britt; Tjiputra, Jerry; Samuelsen, Annette; Yumruktepe, Veli Caglar & Li, Camille [Show all 9 contributors for this article] (2023). Key physical processes and their model representation for projecting climate impacts on subarctic Atlantic net primary production: A synthesis. Progress in Oceanography. ISSN 0079-6611. 217. doi: 10.1016/j.pocean.2023.103084. Full text in Research Archive Show summary

  Oceanic net primary production forms the foundation of marine ecosystems. Understanding the impact of climate change on primary production is therefore critical and we rely on Earth System Models to project future changes. Stemming from their use of different physical dynamics and biogeochemical processes, these models yield a large spread in long-term projections of change on both the global and regional scale. Here we review the key physical processes and biogeochemical parameterizations that influence the estimation of primary production in Earth System Models and synthesize the available projections of productivity in the subarctic regions of the North Atlantic. The key processes and modelling issues we focus on are mixed layer depth dynamics, model resolution and the complexity and parameterization of biogeochemistry. From the model mean of five CMIP6 models, we found a large increase in PP in areas where the sea ice retreats throughout the 21st century. Stronger stratification and declining MLD in the Nordic Seas, caused by sea ice loss and regional freshening, reduce the vertical flux of nutrients into the photic zone. Following the synthesis of the primary production among the CMIP6 models, we recommend a number of measures: constraining model hindcasts through the assimilation of high-quality long-term observational records to improve physical and biogeochemical parameterizations in models, developing better parameterizations for the sub-grid scale processes, enhancing the model resolution, downscaling and multi-model comparison exercises for improved regional projections of primary production.

• Mikkelsen, Nina; Planque, Benjamin; Arneberg, Per; Skern-Mauritzen, Mette; Hansen, Cecilie & Fauchald, Per [Show all 9 contributors for this article] (2023). Multiple stakeholders’ perspectives of marine social ecological systems, a case study on the Barents Sea. Ocean and Coastal Management. ISSN 0964-5691. 242. doi: 10.1016/j.ocecoaman.2023.106724. Full text in Research Archive Show summary

  The Barents Sea ecosystem components and services are under pressure from climate change and other anthropogenic impacts. Following an Ecosystem-based management approach, multiple simultaneous pressures are addressed by using integrative strategies, but regular prioritization of key issues is needed. Identification of such priorities is typically done in a ‘scoping’ phase, where the characterization of the social-ecological system is defined and discussed. We performed a scoping exercise using an open and flexible multi-stakeholder approach to build conceptual models of the Barents Sea social-ecological system. After standardizing vocabulary, a com plex hierarchical model structure containing 155 elements was condensed to a simpler model structure con taining a maximum of 36 elements. To capture a common understanding across stakeholder groups, inputs from the individual group models were compiled into a collective model. Stakeholders’ representation of the Barents Sea social-ecological system is complex and often group specific, emphasizing the need to include social scientific methods to ensure the identification and inclusion of key stakeholders in the process. Any summary or simpli fication of the stakeholders’ representation neglects important information. Some commonalities are highlighted in the collective model, and additional information from the hierarchical model is provided by multicriteria analysis. The collective conceptual stakeholder model provides input to an integrated overview and strengthens prioritization in Ecosystem-based management by supporting the development of qualitative network models. Such models allow for exploration of perturbations and can inform cross-sectoral management trade-offs and priorities

• Ottersen, Geir & Holt, Rebecca Emma (2022). Long-term variability in spawning stock age structure influences climate–recruitment link for Barents Sea cod. Fisheries Oceanography. ISSN 1054-6006. 32(1), p. 91–105. doi: 10.1111/fog.12605. Full text in Research Archive Show summary

  Fish populations may spawn a vast number of offspring, while only a small and highly variable fraction of a new cohort survives long enough to enter into the fisheries as recruits. It is intuitive that the size and state of the spawning stock, the adult part of the fish population, is important for recruitment. Additionally, environmental conditions can greatly influence survival through vulnerable early life stages until recruitment. To understand what regulates recruitment, an essential part of fish population dynamics, it is thus necessary to explain the impact of fluctuations in both spawning stock and environment, including interactions. Here, we examine if the connection between the environment and recruitment is affected by the state of the spawning stock, including biomass, mean age and age diversity. Specifically, we re-evaluate the hypothesis stating that recruitment from a spawning stock dominated by young fish and few age classes is more vulnerable to environmental fluctuations. We expand upon earlier work on the Barents Sea stock of Atlantic cod, now with data series extended in time both backwards and forwards to cover the period 1922–2019. While our findings are correlative and cannot prove a specific cause and effect mechanism, they support earlier work and strengthen the evidence for the hypothesis above. Furthermore, this study supports that advice to fisheries management should include considerations of environmental status.

• Ottersen, Geir; Constable, Andrew J.; Hollowed, Anne B.; Holsman, Kristin K.; Melbourne-Thomas, Jess & Muelbert, Mônica M.C. [Show all 7 contributors for this article] (2022). Climate change impacts on polar marine ecosystems: Toward robust approaches for managing risks and uncertainties. Frontiers in Climate. 3:733755, p. 1–11. doi: 10.3389/fclim.2021.733755. Full text in Research Archive Show summary

  The Polar Regions chapter of the Intergovernmental Panel on Climate Change's Special Report on the Ocean and Cryosphere in a Changing Climate (SROCC) provides a comprehensive assessment of climate change impacts on polar marine ecosystems and associated consequences for humans. It also includes identification of confidence for major findings based on agreement across studies and weight of evidence. Sources of uncertainty, from the extent of available datasets, to resolution of projection models, to the complexity and understanding of underlying social-ecological linkages and dynamics, can influence confidence. Here we, marine ecosystem scientists all having experience as lead authors of IPCC reports, examine the evolution of confidence in observed and projected climate-linked changes in polar ecosystems since SROCC. Further synthesis of literature on polar marine ecosystems has been undertaken, especially within IPCC's Sixth Assessment Report (AR6) Working Group II; for the Southern Ocean also the Marine Ecosystem Assessment for the Southern Ocean (MEASO). These publications incorporate new scientific findings that address some of the knowledge gaps identified in SROCC. While knowledge gaps have been narrowed, we still find that polar region assessments reflect pronounced geographical skewness in knowledge regarding the responses of marine life to changing climate and associated literature. There is also an imbalance in scientific focus; especially research in Antarctica is dominated by physical oceanography and cryosphere science with highly fragmented approaches and only short-term funding to ecology. There are clear indications that the scientific community has made substantial progress in its ability to project ecosystem responses to future climate change through the development of coupled biophysical models of the region facilitated by increased computer power allowing for improved resolution in space and time. Lastly, we point forward—providing recommendations for future advances for IPCC assessments.

• Rørvik, Carl Jakob; Bogstad, Bjarte; Ottersen, Geir & Kjesbu, Olav Sigurd (2022). Long-term interplay between harvest regimes and biophysical conditions may lead to persistent changes in age at sexual maturity of Northeast Arctic cod (Gadus morhua). Canadian Journal of Fisheries and Aquatic Sciences. ISSN 0706-652X. 79(4), p. 576–586. doi: 10.1139/cjfas-2021-0068. Full text in Research Archive Show summary

  This investigation commenced by constructing principal maturation schedule equations as a function of fishing mortality (F), key biophysical factors and a term attributed to fisheries-induced adaptive change (FIAC). Following the onset of industrial trawl fishery on the model stock, Northeast Arctic cod (NEAC; Gadus morhua) (1934–2020), F on immature age group 5–8 years (F5-8) increased and mean age at 50% maturity (A50) decreased from ≈10 years in the late 1940s to ≈7 years today. Large annual fluctuations in total stock biomass (TSB), sea temperature (KolaT) and F5-8 were used to better understand A50 responses. In the model, the annual accumulation of F5-8 drives FIAC. The model includes the option that NEAC may sustain F5-8 up to a certain level (F_bal) before FIAC becomes statistically evident, with F_bal falling between 0.00 and 0.40 for A50. This dynamic range in F_bal indicates a sophisticated, underlying adaptive response. Independent of F_bal, our analysis clarifies that FIAC is necessary to explain the observed changes in A50.

• Townhill, Bryony; Holt, Rebecca Emma; Bogstad, Bjarte; Durant, Joël; Pinnegar, John K. & Dolgov, Andrey V. [Show all 9 contributors for this article] (2021). Diets of the Barents Sea cod (Gadus morhua) from the 1930s to 2018. Earth System Science Data. ISSN 1866-3508. 13(3), p. 1361–1370. doi: 10.5194/essd-13-1361-2021. Full text in Research Archive Show summary

  A new dataset on the diet of Atlantic cod in the Barents Sea from the 1930s to the present day has been compiled to produce one of the largest fish diet datasets available globally. Atlantic cod is one of the most ecologically and commercially important fish species in the North Atlantic. The stock in the Barents Sea is by far the largest, as a result of both successful management and favourable environmental conditions since the early 2000s. As a top predator, cod plays a key role in the Barents Sea ecosystem. The species has a broad diet consisting mainly of crustaceans and teleost fish, and both the amount and type of prey vary in space and time. The data – from Russia, Norway and the United Kingdom – represent quantitative stomach content records from more than 400 000 fish and qualitative data from 2.5 million fish. Many of the data are from joint collaborative surveys between Norway and Russia. The sampling was conducted throughout each year, allowing for seasonal, annual and decadal comparisons to be made. Visual analysis shows cod diets have changed considerably from the start of the dataset in the 1930s to the present day. There was a large proportion of herring in the diets in the 1930s, whereas in more recent decades capelin, invertebrates and other fish dominate. There are also significant interannual asynchronous fluctuations in prey, particularly capelin and euphausiids. Combining these datasets can help us understand how the environment and ecosystems are responding to climatic changes, and what influences the diet and prey switching of cod. Trends in temperature and variability indices can be tested against the occurrence of different prey items, and the effects of fishing pressure on cod and prey stocks on diet composition could be investigated. The dataset will also enable us to improve parametrization of food web models and to forecast how Barents Sea fisheries may respond in the future to management and to climate change. The Russian data are available through joint projects with the Polar Branch of the Russian Federal Research Institute of Fisheries and Oceanography (VNIRO).

• Koul, Vimal; Sguotti, Camilla; Årthun, Marius; Brune, Sebastian; Dusterhus, Andre & Bogstad, Bjarte [Show all 9 contributors for this article] (2021). Skilful prediction of cod stocks in the North and Barents Sea a decade in advance. Communications Earth & Environment. 2(1). doi: 10.1038/s43247-021-00207-6. Full text in Research Archive Show summary

  Reliable information about the future state of the ocean and fish stocks is necessary for informed decision-making by fisheries scientists, managers and the industry. However, decadal regional ocean climate and fish stock predictions have until now had low forecast skill. Here, we provide skilful forecasts of the biomass of cod stocks in the North and Barents Seas a decade in advance. We develop a unified dynamical-statistical prediction system wherein statistical models link future stock biomass to dynamical predictions of sea surface temperature, while also considering different fishing mortalities. Our retrospective forecasts provide estimates of past performance of our models and they suggest differences in the source of prediction skill between the two cod stocks. We forecast the continuation of unfavorable oceanic conditions for the North Sea cod in the coming decade, which would inhibit its recovery at present fishing levels, and a decrease in Northeast Arctic cod stock compared to the recent high levels.

• Ciannelli, Lorenzo; Neuheimer, Anna B.; Stige, Leif Christian; Frank, Kenneth T.; Durant, Joël & Hunsicker, Mary E. [Show all 10 contributors for this article] (2021). Ontogenetic spatial constraints of sub-arctic marine fish species. Fish and Fisheries. ISSN 1467-2960. p. 1–16. doi: 10.1111/faf.12619. Full text in Research Archive Show summary

  Climate change influences ecological processes and biogeochemical cycles of marine environments. Species may respond and adapt to these changes through shifting spatial distributions, but options may be limited by the required occupancy of essential habitats which are anchored in space. Marine fish species typically have complex life cycles composed of multiple life stages with different degrees of habitat preferences. Limited knowledge of when spatial constraints are most likely to occur in marine fish life cycles has impeded the development of realistic distribution forecasts. In this study, we develop and implement analytical techniques to identify spatial constraints, defined by both the consistency through which a particular geographic area is used year after year, and by the extent of such area with respect to the entire population range. This approach is applied to ten case studies including six groundfish species from the Eastern Bering Sea, three from the Scotian Shelf, and one from the Barents Sea. Our analyses illustrate that the early phase of the species’ life cycle is more spatially constrained than older life stages, and that adult stages are more closely associated with particular temperatures or climate velocities. We detected significant species-specific variability in both the degree to which species are anchored in space throughout their life cycle, and the ontogenetic changes of the geographic association. Some of this variability can be explained by the species life history strategy and this provides promising avenues to extend similar analyses to data poor species. The presence of life history spatial constraints, particularly during early life stages, indicates restrictions exist to changes of spatial distribution and thus questions the assertion that global warming will uniformly result in an increase of harvest at higher latitudes and decreases at lower latitudes. Species distribution models are often parameterized from data based on life stages that are highly variable in space, such as the adult stages during summer months which may result in unrealistic forecasts of distribution. Our study develops ecological and analytical insights that are critical for developing accurate projections of species distributions under different climate change scenarios.

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• Ottersen, Geir; Blenckner, Thorsten; Hátún, Hjálmar; Maar, Marie; Niiranen, Susa & Schourup-Kristensen, Vibe [Show all 7 contributors for this article] (2025). Nordic Marine Ecosystems in a Changing Climate. Nordic Council of Ministers. ISBN 9789289382489. 98 p. doi: 10.6027/temanord2025-541. Full text in Research Archive Show summary

  The aim of the NorMECC project and this report is to make available a good overview of the already observed and expected future responses to climate change of a wide range of marine species in the Nordic waters of the Baltic Sea, the North Sea, the Norwegian and Icelandic Seas, the seas around Greenland, and the Barents Sea. The report reviews and assesses scientific articles and other knowledge sources, including papers published up until February 2025. In addition to this literature review, we also provide a short synopsis of the input from a small, targeted group of Nordic managers and decision makers who were challenged to describe which climate change related pressures they consider to be the largest treats to our marine ecosystems.

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• Ottersen, Geir (2026). Experiences with LLM tools for scientific writing and literature review. Full text in Research Archive Show summary

  I’m sharing my experiences with applying Large Language Model (LLMs) to enhance scientific writing and literature review. The LLM branch of Artificial Intelligence is now totally changing the science writing process and we all must relate to this. I am no expert and this is not a course, but I’ve spent some time trying to get a grip on how to use standard LLMs (Copilot, ChatGPT, etc.) and a couple of more specialized ones (SciSpace, Elicit) to improve my scientific writing and literature review workflow. I’m sure some of you also have done this, but I miss constructive guidelines or recommended tools. Maybe this can be a starting point for exchanging ideas? My presentation has three main parts: i) Motivation – why invest time in LLMs, ii) General tips including better prompting (reasoning strategies, iterative prompting, personalization….) and applying ChatGPT Custom GPTs, and iii) examples of my uses including help to produce abstract, referee work, early stage of literature review, and popular science article from project description.

• Ottersen, Geir & Pascual, Alvaro de (2026). SEACLIM WP4- Ocean Climate Indicators Achievements and Workplan for 2026. Full text in Research Archive
• Ottersen, Geir (2026). Fiskebestander i et varmere hav. Full text in Research Archive
• Ottersen, Geir; Hansen, Cecilie; Hjøllo, Solfrid Sætre; Hordoir, Robinson; Koseki, Mariko & Nilsen, Ina [Show all 8 contributors for this article] (2026). Cod and climate change – projecting the future of the Barents Sea cod stock towards the end of the 21st century. Full text in Research Archive Show summary

  The Barents Sea (BS), is one of the areas where strongest impacts of climate change is expected. Change from ice to open will affect the ecosystem. Climate change will have particular strong impact in the Arctic due to the amplified temperature increase there resulting in a fundamental change from a seasonally ice-covered to a permanently open ocean system. The northern and eastern parts of the Barents Sea (BS), north of Norway and NW Russia, are essentially of arctic nature. The southwestern part of the BS is boreal and heavily influenced by Atlantic water masses, the boundary between the two regimes shifts with the water masses. The Northeast Arctic population of Atlantic cod (Gadus Morhua) is a key player in the BS ecosystem. It is the largest stock of Atlantic cod and of commercial and cultural value to man. It has been monitored for well over 100 years and is likely one of the fish populations with mos accumulated knowledge on response to climate variability. Higher temperature historically been favourable, mainly acting through enhanced recruitment and arger distribution area. In this talk we summarise the main results from several recent studies that explore the state of the BS cod towards the end of the century. More precisely, by means of recent dynamical physical modelling, ecosystem modelling and expert assessments, the responses of cod to a range of downscaled IPCC CMIP6 climate scenarios are given. IPCC has defined a set of scenarios called Shared Socioeconomic Pathways, we explore SSP1–2.6 (low), SSP2–4.5 (intermediate), SSP5–8.5 (extremely high). One approach is by means of the Nemo-NAA10km ocean model, in climate downscaling mode, and the biogeochemical model NORWECOM.e2e (NORWegian ECOlogical Model system end-to-end). Based upon knowledge established form history, the projections of key physical variables (sea temperature, ice…) from Nemo-NAA10km and biogeochemistry (net primary production, gross secondary production) from NORWECOM.e2e, expert evaluations were conducted. BS cod is found to respons positively to climate change, especially the high co2 scenario. This result is supported by a regression analysis, which E2E suggest that increased ocean temperature and abundant zooplankton SSP5–8.5 may lead to a large cod stock. Alternative analyses has been conducted by means of the Nordic and Barents Seas Atlantis model (NoBa Atlantis). This is an end-to-end ecosystem model with 53 species and functional groups. Contrary to above, the NoBa Atlantis analyses concluded that the BS cod will respond negatively to climate warming, and more so under SSP5-8.5 then SSP2-4.5. The decrease in cod was strongly related to a decrease in capelin, their main food. Thus, while ther eis much knowledge on BS cod, the future is still open.

• Ottersen, Geir (2025). Behovet for å forstå regionale effekter av globale klimaendringer. Full text in Research Archive
• Ottersen, Geir (2025). Er klimautfordringene den største trusselen for skreien? Full text in Research Archive
• Ottersen, Geir (2025). Impacts of Climate Change on marine Ecosystems 2025. Full text in Research Archive Show summary

• Crépin, Anne-Sophie; Wu, Xiurou; Ni, Yuanming; Hoel, Alf Håkon; Aanesen, Margrethe & Ekerhovd, Nils-Arne [Show all 9 contributors for this article] (2025). Methods for social-ecological systems analysis and management in Arctic and sub-Arctic seas. Full text in Research Archive
• Ottersen, Geir (2024). Havets rolle i karbonkretsløpet og hvordan det påvirker klimaendringene. Full text in Research Archive
• Ottersen, Geir (2024). Impacts of Climate Change on Marine Ecosystems. Full text in Research Archive
• Ottersen, Geir (2024). Marine Heat Waves in IPCC SROCC and Northern sea areas MHW reports – a brief overview. Full text in Research Archive
• Ottersen, Geir (2024). NorScen, overblikk, ventede bidrag. Full text in Research Archive
• Langangen, Øystein Ole Gahr; Olsen, Tora; Durant, Joël; Ottersen, Geir & Eriksen, Elena (2024). Poleward shift in spawning leads to smaller Atlantic cod offspring. Full text in Research Archive
• Langangen, Øystein Ole Gahr; Olsen, Tora; Durant, Joël; Ottersen, Geir & Eriksen, Elena (2024). Poleward shift in spawning leads to smaller Atlantic cod offspring. Full text in Research Archive
• Ottersen, Geir (2024). Klimaendringer påvirker havets økosystem. [Journal]. NorFishing Magasin. Full text in Research Archive
• Ottersen, Geir (2024). Havforskning: Menneskelig påvirkning haster mest. Full text in Research Archive
• Hansen, Cecilie; Aarflot, Johanna Myrseth; Husson, Berengere; Fauchald, Per; Johansen, G.O. & Jørgensen, Lis Lindal [Show all 11 contributors for this article] (2023). Risk of negative cumulative human impact on scientific-based valuable and vulnerable areas in Norwegian waters. Full text in Research Archive
• Ottersen, Geir (2023). Store klimaendringer i de nordiske havområdene. [Internet]. UNRIC FNs regionale informasjonskontor for Vest-Europa. Full text in Research Archive
• Ottersen, Geir (2023). Havnivåstigning - intervju av journalist Petter M Udland. [Radio]. P4. Full text in Research Archive
• Ottersen, Geir (2023). Slik endres Norge - Fiske-flukten. [Journal]. vg.no. Full text in Research Archive
• Ottersen, Geir (2023). Klimaendringer og effekter i de nordiske havområdene: NY RAPPORT Hvordan vil klimaendringene arte seg i de ulike nordiske havområdene? Hvilke konsekvenser vil de få for våre økosystemer og fiskeriressurser? Full text in Research Archive
• Ottersen, Geir & Holt, Rebecca Emma (2023). Spawning stock age structure and climate combined cause long-term fluctuations in recruitment – demonstrated for the Norwegian spring-spawning herring stock? Full text in Research Archive
• Ottersen, Geir (2023). Klimaendringene: Operaen i Oslo drukner ikke, men Bryggen i Bergen vil bli oversvømt. [Internet]. Forskning.no. Full text in Research Archive
• Ottersen, Geir (2023). Fersk klimarapport: – Konsekvensene for natur og menneskehet er omfattende og alvorlige. [Internet]. Kystens Næringsliv - kystens.no. Full text in Research Archive
• Ottersen, Geir (2023). Dette mener han kan gi utfordringer for havbruksnæringen. [Internet]. Kyst.no. Full text in Research Archive
• Ottersen, Geir (2023). Slik vil klimaendringene påvirke oss i Norden. [Internet]. hi.no. Full text in Research Archive
• Ottersen, Geir (2023). Advarer mot «marine hetebølger». [Internet]. NRK Nyhetssenter Troms og Finnmark. Full text in Research Archive
• Ottersen, Geir (2023). Advarer mot "Marine hetebølger". [Radio]. NRK Dagsnytt. Full text in Research Archive
• Ottersen, Geir (2023). NRK P2 Studio 2 podkast Klimarapport for nordiske havområder. [Radio]. NRK P2 Studio 2. Full text in Research Archive
• Ottersen, Geir (2023). Slår hardest inn i nord. [Internet]. kystogfjord.no. Full text in Research Archive
• Ottersen, Geir (2023). Heading into a climate that humanity has never experienced before. [Internet]. Sciencenorway.no . Full text in Research Archive
• Ottersen, Geir & Møllerløkken, Sunniva (2023). Se etter delfiner fremover. [Internet]. TV2.no. Full text in Research Archive
• Ottersen, Geir (2023). Forsker: – På vei inn i et klima som menneskeheten aldri før har opplevd. [Journal]. Fædrelandsvennen. Full text in Research Archive
• Ottersen, Geir (2023). Hvordan sikre levende marine ressurser og sunne økosystemer for nåværende og fremtidige generasjoner. Full text in Research Archive
• Ottersen, Geir (2023). Forsker: – På vei inn i et klima som menneskeheten aldri før har opplevd. [Journal]. Finansavisen. Full text in Research Archive
• Ottersen, Geir (2023). Forsker: – På vei inn i et klima som menneskeheten aldri før har opplevd. [Internet]. NTB. Full text in Research Archive
• Ottersen, Geir & Holt, Rebecca Emma (2022). Spawning stock age structure and climate combined cause long term fluctuations in Barents Sea cod recruitment. Full text in Research Archive
• Ottersen, Geir & Holt, Rebecca Emma (2022). Barents Sea cod recruitment less affected by temperature variability when spawning stock includes old, large fish. Full text in Research Archive
• Ottersen, Geir; Meeren, Gro Ingleid van der; Hansen, Cecilie; Skogen, Morten D.; Maar, Marie & Sejr, Mikael Kristian [Show all 10 contributors for this article] (2022). Studies of marine ecosystems in the Barents Sea and off West Greenland. Full text in Research Archive
• Ottersen, Geir (2022). NorScen: Presentasjon av hva som skal gjøres. Full text in Research Archive
• Ottersen, Geir (2022). Klimaendringer i nordiske havområder og effekter på viktige fiskebestander. Full text in Research Archive
• Ottersen, Geir (2022). Impacts of climate change on marine ecosystems. Full text in Research Archive
• Ottersen, Geir (2022). Observed and projected climate change in Nordic marine areas and impacts on important fish stocks. Full text in Research Archive
• Tjiputra, Jerry; Myksvoll, Mari; Sandø, Anne Britt; Samuelsen, Annette; Yumruktepe, Caglar & Li, Camille [Show all 8 contributors for this article] (2021). Key physical processes for evaluating climate impacts on subarctic primary production. Full text in Research Archive
• Mikkelsen, Nina; Planque, Benjamin; Arneberg, Per; Skern-Mauritzen, Mette; Hansen, Cecilie & Fauchald, Per [Show all 9 contributors for this article] (2021). Multiple stakeholders perspectives on marine ecological systems, a case study on the Barents Sea. Full text in Research Archive
• Mikkelsen, Nina; Skern-Mauritzen, Mette; Ottersen, Geir; Armstrong, Claire W.; Arneberg, Per & Fauchald, Per [Show all 9 contributors for this article] (2021). BarentsRisk- assessing cumulative impacts on the Barents Sea Ecosystem. Full text in Research Archive
• Ottersen, Geir & Holt, Rebecca Emma (2021). Hva spiser torsken - modellstudier på torskens diett og næringsnettet i Barentshavet. Full text in Research Archive
• Ottersen, Geir (2021). Climate and Change in Fish Distribution. Full text in Research Archive
• Ottersen, Geir (2021). Global oppvarming: - Slukes: - Ekstremt scenario. [Journal]. Dagbladet. Full text in Research Archive
• Ottersen, Geir (2021). Climate changes the distribution of valuable fish stocks – a challenge for management and sustainable fisheries. Full text in Research Archive
• Sandven, Stein; Sagen, Hanne; Pirazzini, Roberta; Beszczynska-Möller, Agnieszka; Voss, Peter & Danielsen, Finn [Show all 14 contributors for this article] (2021). Building integrated Arctic observing systems from in situ platforms. Full text in Research Archive Show summary

  A major objective of the H2020 INTAROS project is to strengthen and extend the Arctic in situ observing systems for atmosphere, ocean and terrestrial disciplines (www.intaros.eu ). The in situ observing systems are only used in very limited areas, due technological and infrastructures limitations. Extensive research efforts are undertaken in order to develop, test and operate new observing platforms under Arctic conditions. In addition to scientific observing systems, there are Community-Based Monitoring programmes where data are collected by local communities to support their requirements for information about climate change, natural resources, and other topics. A major challenge in Arctic data management and data sharing is the heterogeneity and complexity in data collected in the difference scientific disciplines. INTAROS has focus on improving the data accessibility from a large number of distributed observing systems and to develop adequate data management systems. To enable data sharing it is necessary to develop interoperability between observing systems and data systems. The observing systems are developed in agreement with the overarching principles FAIR (Findable Accessible, Interoperable, Reusable) and CARE (Collective benefit; Authority to control; Responsibility; Ethics). Data provided by the project partners are available from a number of different data repositories via the INTAROS data catalogue (https://catalog- intaros.nersc.no/).

• Ottersen, Geir; Sejr, Mikael K; Kruschke, Tim; Meeren, Gro Ingleid van der; Sagen, Hanne & Solgaard, Anne [Show all 9 contributors for this article] (2021). Demonstrating applications of an Integrated Arctic Observing System towards selected, diverse stakeholder groups. Full text in Research Archive Show summary

  The overall objective of INTAROS is to build an efficient and sustainable integrated Arctic Observation System (iAOS) by extending, improving and unifying existing systems. An important part of this is the work done in INTAROS’ WP6 to demonstrate application of the iAOS by delivering a suite of products targeted at issues of societal importance. These pilot applications will demonstrate services towards end-users. WP6 will show the iAOS’ capability for advancing the economic role of the Arctic by providing support for better-documented processes and better-informed decisions within key sectors such as shipping, petroleum, fishing, and tourism. Further, WP6 aims to demonstrate how the iAOS may be applied to develop the accuracy of climate models, improve the understanding of biogeochemical cycles and ecosystem functioning, enhance fisheries and environmental management, increase the level of preparedness towards natural hazards, and develop better management and decision making concepts for selected local communities. Concrete demonstrations include for heavy snow precipitation on Svalbard, hydrographic data in the Barents Sea, trawl data on fish off Greenland, and modelling of large-scale fresh-water flow. In this presentation we will focus on the Highlights from WP6 and provide a Synthesis of results. We will also provide information about and lessons learned from our work and implication for future work. WP6 will provide input to the INTAROS roadmap.

• Ottersen, Geir (2021). Presentasjon av prosjektet CoDINA - Cod DIet and food web dyNAmics. Full text in Research Archive
• Ottersen, Geir (2021). Oseanografiske katastrofer. Full text in Research Archive
• Ottersen, Geir (2021). Arctic marine ecosystems: impacts of climate change. Full text in Research Archive
• Ottersen, Geir (2020). Hovedfunn fra FNs klimapanel sin spesialrapport på hav og islagte områder. Full text in Research Archive
• Ottersen, Geir (2020). Ny havrapport fra FN’s klimapanel: Klimaendringer og konsekvenser for fisk, fiskerier og havbruk. Full text in Research Archive
• Ottersen, Geir (2020). Impacts of climate change on marine ecosystems Lecture at BIO 4331, IBV, University of Oslo. Full text in Research Archive
• Ottersen, Geir (2020). Klimaendringer og effekter på marine økosystemer og miljøverdier. Full text in Research Archive
• Mikkelsen, Nina; Skern-Mauritzen, Mette; Ottersen, Geir; Armstrong, Claire W.; Arneberg, Per & Fauchald, Per [Show all 9 contributors for this article] (2020). Defining ecosystem vulnerabilities and risks of cumulative impacts in a unifying Ecosystem Risk Assessment Framework. Full text in Research Archive
• Ottersen, Geir & Torsvik, Nils (2019). Nordsjøen tømmes for fisk - Barentshavet fylles av torsk. [Journal]. Fiskeribladet. Full text in Research Archive
• Holt, Rebecca Emma; Bogstad, Bjarte; Durant, Joël; Dolgov, Andrey V. & Ottersen, Geir (2019). Erratum: Barents Sea cod (Gadus morhua) diet composition: Long-term interannual, seasonal, and ontogenetic patterns (ICES Journal of Marine Science (2019) DOI: 10.1093/icesjms/fsz082). ICES Journal of Marine Science. ISSN 1054-3139. 76(6), p. 1936–1936. doi: 10.1093/icesjms/fsz117. Full text in Research Archive
• Strandberg, Torgeir & Ottersen, Geir (2019). Dette skremte nordmannen som var med på å skrive FNs klimarapport. [Journal]. aftenposten.no. Full text in Research Archive
• Ottersen, Geir (2019). Intervju om FNs Klimarapport på hav og islagte områder. [TV]. NRK1 Dagsrevyen. Full text in Research Archive
• Ottersen, Geir & Lorentzen, Erlend Astad (2019). Ropar varsku om varmare hav. [Internet]. https://www.hi.no/. Full text in Research Archive
• Andersson, Atle & Ottersen, Geir (2019). Forsker: – Urovekkende stigning på havnivået. [Journal]. Bergens Tidende. Full text in Research Archive
• Rogne, Sissel; Haugan, Peter M.; Ottersen, Geir & Vikebø, Frode Bendiksen (2019). Informasjon til HKH Kronprins Haakon om klimaendringer og effekter av disse. Full text in Research Archive
• Andersson, Atle & Ottersen, Geir (2019). Forsker-alarm: – Urovekkende havnivåstigning. [Internet]. sysla.no. Full text in Research Archive
• Lorentzen, Erlend Astad & Ottersen, Geir (2019). Roper varsko om varmere hav. [Internet]. https://www.kystogfjord.no/. Full text in Research Archive
• Lorentzen, Erlend Astad & Ottersen, Geir (2019). Roper varsku om varmare hav. [Internet]. www.forskning.no. Full text in Research Archive
• Ottersen, Geir (2019). IPCC SROCC: Havet på vei inn i en ny tilstand. Full text in Research Archive
• Myksvoll, Mari Skuggedal; Adam, Anne-Catrin; Agnalt, Ann-Lisbeth; Andersen, Lasse Berg; Asplin, Lars & Bøhn, Thomas [Show all 44 contributors for this article] (2026). Effekten av klimaendringer på risiko for dårlig dyrevelferd og negative miljøeffekter av fiskeoppdrett – kunnskapsstatus. Havforskningsinstituttet. doi: https:/www.hi.no/hi/nettrapporter/rapport-fra-havforskningen-2026-20. Full text in Research Archive Show summary

  Klimaendringene som allerede påvirker norske kyst- og fjordområder fører til økt vanntemperatur, hyppigere marine hetebølger, større nedbørsmengder, mer avrenning fra land (næringsstoffer, miljøgifter og avløp), lavere saltholdighet og redusert oksygennivå i vannmassene. Disse fysiske og kjemiske klimaendringene fører til mindre robuste økosystemer, der samlet påvirkning endres og vil redusere deres toleranse for miljøeffekter fra akvakultur. Oppvarmingen av havet og den økende forekomsten av ekstreme temperaturhendelser skaper et mer utfordrende miljø for både oppdrettet og vill laksefisk, og miljøendringene forventes å forsterkes frem mot 2050. For oppdrettslaks innebærer et varmere klima at viktige fysiologiske terskler overskrides oftere. Laks har optimal vekst ved 10–14 °C, men appetitt og vekst reduseres markant når temperaturen nærmer seg 18–19 °C. Ved temperaturer over 20 °C slutter fisken å spise, og ved langvarige perioder over 22 °C øker dødeligheten. Med økende temperatur faller oksygeninnholdet i vannet, noe som gir en dobbel belastning der fisken både trenger mer oksygen, men samtidig får mindre tilgang på det. Kombinasjonen varme og hypoksi gir økt sannsynlighet for stress, dårligere immunfunksjon, høyere forekomst av sykdommer og flere produksjonslidelser som grå stær (katarakt). Stor laks er særlig utsatt, og også triploid (steril) laks viser redusert robusthet i varmere og mer oksygenfattige miljøer. Det antas at smittepresset fra lakselus vil øke, både på grunn av raskere generasjonstid, høyere smitteevne og høyere produksjon av lus ved økt vanntemperatur. For å holde lusetallene nede vil antall avlusninger sannsynligvis øke, noe som i kombinasjon med økt temperatur og redusert oksygenmetning kan gi økt dødelighet. Klimaendringene forventes derfor å forsterke kjente velferdsproblemer ved at oppdrettslaksen oftere utsettes for håndtering og dermed blir mer sårbar for utvikling av sykdom. Miljøeffektene fra lakseoppdrett på vill laksefisk vil sannsynligvis også endre seg med endringer i klima. Som for oppdrettsfisken, vil økt smittepress fra lakselus kunne gi økt påslag av lakselus på vill laksefisk. Dette er en spesielt alvorlig utfordring for sjøørret og sjørøye, som oppholder seg lenge i kystnære områder. Samtidig ventes klimadrevne endringer i sykdomsbildet. Hvilke er høyst usikkert, men eksempler kan inkludere økende forekomst av bakterielle sykdommer som pasteurellose og piscirickettsiose, og mer amøbegjellesykdom i perioder med høy temperatur og saltholdighet. Økt forekomst av sykdom i oppdrett vil kunne øke sannsynligheten for at også vill laksefisk blir smittet og utvikler sykdom. I tillegg til endret belastning fra fiskeoppdrett blir også vill laksefisk påvirket av de samme klimaendringene, men på ulike måter avhengig av art. Sjørøya er den mest klimautsatte arten, siden den er tilpasset lave temperaturer og reagerer med stress og svekket overlevelse når havet blir varmere. Sjøørret kan i noen tilfeller oppleve økt vekst i varmere vann, og tåler høyere temperaturer bedre enn sjørøya. I områder med begge arter kan derfor sjørøya møte økt konkurranse fra sjøørreten. Vill laksefisk påvirkes gjennom endrede temperatur- og vannføringsforhold i elver, forskjøvet tidspunkt for smoltutvandring og endringer i næringstilgang i havet. Tidligere tidspunkt for smoltutvandring kan bidra til at økt smittepress fra lakselus ikke gir like stort utslag for laksen som for sjøørret og sjørøye. Samlet sett antas det likevel at sannsynligheten for negativ påvirkning fra oppdrett på vill laksefisk øker, særlig gjennom mer lakselus, mer smitte og større belastning på svekkede bestander. Klimaendringer forventes også å øke sannsynligheten for rømming. Mer ekstremvær og økt behov for håndtering og avlusning øker sannsynligheten for rømming og en større andel rømt fisk kan nå elvene og ta seg opp til gyteplassene. Dette øker sannsynligheten for genetisk innkryssing med villaks, som igjen kan bidra til å svekke populasjonenes robusthet mot ytre påvirkning. Villaksbestander som allerede er svekket av klimaendringer, sykdom og redusert mattilgang vil være spesielt utsatt. En robust populasjon er det viktigste grunnlaget for å tåle både naturlige og menneskeskapte stressfaktorer. Når klimaendringene svekker denne robustheten, endres også vurderingen av risiko fra oppdrettsaktivitet. Ikke bare kan påvirkningene fra oppdrett forverres, men klimaendringene endrer også rammene for hva som er bærekraftig og hva naturen faktisk tåler. Også miljøeffekter fra organiske utslipp, miljøgifter og legemidler antas å endre seg med klimaendringene. Utslippsmengden av næringssalter fra fiskeoppdrett vil ikke endre seg med endret klima, men effekten av utslippene kan påvirke planteplanktonproduksjon og biodiversitet i makroalgesamfunn. Dårligere vannutskiftning gjør at organisk materiale brytes ned langsommere, og kan føre til opphopning av utslipp som miljøgifter og legemidler. Økende temperatur gir mer begroing av oppdrettsnøtene og kan dermed gi økt bruk av antigroemidler som kobber eller andre kjemiske forbindelser som hindrer alge- og plantevekst. Flere avlusninger kan føre til større utslipp av legemidler, som kan få sterkere effekt på sårbare arter i et varmere og mer belastet økosystem. Samlet peker rapporten på et tydelig mønster: klimaendringene forsterker mange av dagens utfordringer knyttet til fiskevelferd, sykdom, rømming og miljøpåvirkning. Dette fører til et mindre robust økosystem og en høyere samlet risiko for både oppdrettsfisk, vill laksefisk og marint miljø. Det konkluderes med at betydelige kunnskapshull fortsatt finnes, særlig knyttet til patogeners respons på klimaendringer, langtidsendringer i fjordsirkulasjon og ernæringsbehov hos oppdrettslaks i varmere klima, og at fremtidig forvaltning vil kreve ny kunnskap, ny teknologi og mer tilpasningsevne enn i dag.

• Ottersen, Geir; Arneborg, Lars; Maar, Marie; Almroth-Rosell, Elin; Fredriksson, Sam & Gonzalez, Silvana [Show all 16 contributors for this article] (2025). Effects of climate change on future environment and marine life in the Nordic sea areas. Nordic Council of Ministers. ISSN 9789289382403. doi: 10.6027/temanord2025-527. Full text in Research Archive Show summary

  The Nordic Council of Ministers sees a need to increase our understanding of the effects of future climate change specifically on the Nordic sea areas and has asked for regional analyses and assessments. NorScen aims to address the request and the results are presented in this report

• Beumont, Nicola; Biquet, Juliette Aminian; Gonzalez, Enrique Blanco; Calderwood, Julia; Winter, Renske de & Fonseca, Tainá [Show all 39 contributors for this article] (2024). Navigating the Future VI: Placing the Ocean within the wider Earth system. Position Paper 28 of the European Marine Board. European Marine Board. ISSN 9789464206265. Full text in Research Archive
• Ottersen, Geir; Børsheim, Knut Yngve; Arneborg, Lars; Maar, Marie; Schourup-Kristensen, Vibe & Rosell, Elin Almroth [Show all 7 contributors for this article] (2023). Observed and expected future impacts of climate change on marine environment and ecosystems in the Nordic region. Havforskningsinstituttet. Full text in Research Archive Show summary

  The UN's Intergovernmental Panel on Climate Change (IPCC) reports are comprehensive, thorough and important, but they cover the whole world and this is at the expense of scope and precision on a regional scale. Specifically, the Nordic region is not covered as a separate area or specific characteristics of our regional seas highlighted. It is particularly unsatisfactory that the global models used to simulate future climate and climate effects do not have a high enough spatial resolution to serve as a good basis for decisions on a Nordic scale. Against this background, the Nordic Council of Ministers saw a need for increased knowledge about the effects of climate change on Nordic waters. This resulted in the project "Nordic climate scenarios" (NorScen), which runs from 2022 to 2024 and is initiated and funded by the Council of Ministers.

• Ottersen, Geir; Sejr, Mikael K.; Döscher, Ralf; Goeckede, Mathias; Iversen, Lisbeth & Kruschke, Tim [Show all 66 contributors for this article] (2022). Deliverable 6.19 Synthesis report from WP6: Application studies of Arctic Observing Systems towards stakeholders. Nansen Environmental and Remote Sensing Center, Norway Bergen, Norway. Full text in Research Archive Show summary

  This report gives an overview of the activities, results and impacts of INTAROS Work Package 6 (WP6). The aim of WP6 is to demonstrate how an integrated observation system can be of specific benefit for society at local, regional or pan-Arctic scale. Through WP6 we show the capability of an enhanced Arctic Observation System towards advancing the economic role of the Arctic by providing support for better-documented processes and better-informed decisions within key sectors such as shipping, petroleum, fishing, and tourism. Further, WP6 demonstrates how the Arctic Observation system may be applied to further develop the accuracy of climate models, improve the understanding of biogeochemical cycles and ecosystem functioning, enhance fisheries and environmental management, increase the level of preparedness towards natural hazards, and develop better management and decision making concepts for selected local communities. Through WP6 INTAROS demonstrates enhanced data search and retrieval, assimilation into models, validation of estimated and projected climate parameters, scientific analysis, decision-support and policy-making. Following a general introduction to INTAROS WP6, eight chapters summarize, for each topic covered, the main activities and results, data and models used, stakeholder/user benefits, and further development and exploitation of results. The topics span broadly and target very different end-user groups but they all share the same overall challenge: how to synthesize data across time and space from different sources, formats and scientific disciplines into aggregated synoptic data products that are relevant for end-users. The following topics are addressed: Improving skill of model predictions in the Arctic, Applying observations and models for environmental and fisheries management, Ice-ocean statistics, Remote sensing applications, Natural hazards in the Arctic, Greenhouse gas exchange in the Arctic, Case studies of community-based observing systems and Benefits of ocean observing for blue growth in the Arctic. The report then describes concrete showcases, software applications. Selected main results across WP6 are then presented, before the report ends with conclusions and perspectives.

• Sandven, Stein; Sagen, Hanne; Pirazzini, Roberta; Beszczynska-Möller, Agnieszka; Danielsen, Finn & Goncalves, David [Show all 15 contributors for this article] (2022). Deliverable 1.11 Final synthesis report. INTAROS Project. Full text in Research Archive
• Hansen, Cecilie; Hjøllo, Solfrid Sætre; Ottersen, Geir & Skern-Mauritzen, Mette (2022). MILJØVERDIERS SÅRBARHET I NORSKE HAVOMRÅDER — En gjennomgang av sårbarhet til ulike typer påvirkninger i foreslåtte særlig verdifulle og sårbare områder i norske havområder. Havforskningsinstituttet. Full text in Research Archive Show summary

  Det er gjennomført en kunnskapsbasert vurdering av sårbarhet med konfidens for de viktigste påvirkninger på miljøverdier i norske havområder generelt, og for hvert av områdene som er foreslått som Særlig verdifulle og sårbare (Eriksen mfl. 2021). Sårbarhetsvurderingene er gjort for ni miljøverdier, dvs samlegrupper som representerer isbiota, planteplankton, dyreplankton, tang, tare og ålegras, mesopelagisk fauna, fisk, bunnsamfunn, sjøfugl og sjøpattedyr, i tillegg til for miljøverdien “næringsnett”, som viser sammenhengen mellom ulike organismer i et økosystem. Flere av miljøverdiene er videre delt opp i undergrupper, slik at det totalt sett er 21 miljøverdier. Sårbarheten for hver av disse er vurdert for 17 ulike påvirkninger: barrierer, bifangst, elektromagnetiske felt, fiske og fangst, forstyrrelser, forsøpling, forurensning, forurensning fra olje, fysisk påvirkning, fremmede arter, næringsstoffer, nedslamming, tap av habitat (forsegling), undervannsstøy, uthenting av ikke-levende ressurser, utilsiktet tap, og klimaendringer.

• Hansen, Cecilie; Aarflot, Johanna Myrseth; Eriksen, Elena; Husson, Berengere; Fauchald, Per & Johansen, Geir Odd [Show all 12 contributors for this article] (2022). Samlet påvirkning i foreslåtte særlig verdifulle og sårbare områder i norske havområder. Havforskningsinstituttet. Full text in Research Archive Show summary

  I dette arbeidet er det gjort en vurdering av risiko fra samlet påvirkning med tilhørende usikkerhet for aktive sektorer i norske havområder, for hvert av havområdene Nordsjøen, Norskehavet og Barentshavet, og for hvert av de 19 foreslåtte særlig verdifulle og sårbare områdene (SVO). Resultatene i denne rapporten bør sees på som en første og midlertidig versjon, da det er aller første gang rammeverket benyttes for norske havområder. All informasjon om sektorenes aktivitet er tatt fra en representativ periode (2017-2019), og speiler så nær som mulig dagens aktivitet. Vi har valgt å ikke benytte nyere data, da pandemien påvirket noen av sektorene i stor grad. Akuttutslipp og andre uhell er ikke gjenstand for vurdering i denne rapporten. Usikkerhet knyttet til eksponering (tid og rom) og sårbarhet er inkludert i vurderingene. Det er stor variasjon i usikkerheten, både sektor-relatert og relatert til miljøverdi og/eller påvirkningsfaktor. Dette arbeidet bygger på rapporten Særlig verdifulle og sårbare områder (SVO) i norske havområder – Miljøverdi og Miljøverdiers sårbarhet for påvirkninger. Her tar vi i bruk ODEMM (Options for Delivering Ecosystem-based Marine Management) rammeverket for å vurdere risiko for negativ påvirkning.

• Sandven, Stein & Ottersen, Geir (2022). INTAROS D6.19 Synthesis report from WP6: Application studies of Arctic Observing Systems towards stakeholders. Nansen Environmental and Remote Sensing Center. Full text in Research Archive
• Beszczynska-Möller, Agnieszka; Ahlstrøm, Andreas; Pirazzini, Roberta; Navarro, Francisco; Cheng, Bin & Babin, Marcel [Show all 35 contributors for this article] (2022). Deliverable 3.16 Synthesis and technical recommendations. INTAROS Project. Full text in Research Archive Show summary

  This document provides a summary of sensors, platforms, and observing systems implemented during INTAROS field campaigns and presents technical recommendations based on experience gained from operating these components for collecting in situ observations during the project. This document is intended to: – Shortly summarize details of all individual sensors, platforms, and systems developed and deployed during INTAROS for collecting in situ measurements in the cryospheric, ocean, atmospheric and terrestrial domains, – Provide main recommendations for the technology used in INTAROS with the respect to become a component of a future sustained Arctic observing system, – Describe main limitations of technology used and recommendations to overcome these limitations to enable including this technology in a future observing system, – Overview other technical solutions which could better replace or complement technology used during INTAROS to provide similar set of observations for a future observing system, – Identify and describe cross-cutting technical recommendations based on recommendations for individual systems, – Summarize main challenges and achievements in implementing in situ observations in WP3, – Summarize main technical recommendations from WP3 for use in the INTAROS Roadmap for a future integrated Arctic observing system INTAROS has collaborated with many other field programs and projects which have contributed to the results in WP3. These programs and projects are listed in Annex A. A summary of platforms and sensors developed and implemented during INTAROS, including main challenges and final outcomes, is provided in Annex B.

• Johannessen, Truls; Beszczynska-Möller, Agnieszka; Roden, Nicholas Patrick; Lange, Tor De; Touzeau, Alexandra & Sodemann, Harald [Show all 23 contributors for this article] (2021). Deliverable 3.11 Final implementation and data: North of Svalbard. INTAROS Project. Full text in Research Archive Show summary

  This document, Deliverable 3.11 Final implementation of the observing system: Data delivery and report on results of the observing systems north of Svalbard, provides an overview of platforms, sensors, and samplers which were implemented north of Svalbard for various periods in 2017-2020, describes multidisciplinary data collected by different instruments, and addresses the performance of the employed systems and their applicability for a future sustained observing system. The main goal of Task 3.2 is to deliver in situ ocean and sea ice observations collected during two INTAROS field seasons (and partially also during the initial test field season) and to provide recommendations for future implementation of the moored observing system north of Svalbard that can be applied to define a roadmap for observing future changes in the Arctic. The aim is to make comprehensive observations of the ongoing climate and environmental change that can also be applied as a validation tool for conceptual and three-dimensional modelling. The first implementation of the observing system North of Svalbard was deployed successfully in August 2018 using the Norwegian Coast Guard icebreaker KV Svalbard and retrieved with the same vessel in August/September and with the research icebreaker RV Kronprins Håkonin September and November 2019. All recovered instrument and sensor provided full data return therefore a full annual cycle of multidisciplinary data was obtained for 2018-2019. The second field deployment took place in 2019-2020 (one mooring remained until 2021) and included mostly moorings instrumented for measurements of ocean physical variables (and dissolved oxygen) at the main INTAROS line north of Svalbard and additional instruments and sensors for biogeochemical measurements at the deep INTAROS mooring in the Nansen Basin (deployed under Task 3.4). INTAROS moorings north of Svalbard were deployed from the research icebreaker RV Kronprins Håkon in November 2019and recovered during the CAATEX cruises with the Norwegian Coast Guard icebreaker KV Svalbard in August and November 2020 and in June 2021 as part of the UAK 2021. Field operations in 2020 and 2021 were extremely difficult in terms of logistics and ship access under the limitations due to COVID-19.

• Buch, Erik; Pirazzini, Roberta; Tjernstrøm, Michael; Danielsen, Finn; Möller, Agnieszka B. & Ottersen, Geir [Show all 13 contributors for this article] (2021). INTAROS D1.9. Revised requirement report for Arctic observations. Nansen Environmental and Remote Sensing Center. Full text in Research Archive
• Hamre, Torill; Sagen, Hanne; Sandven, Stein; Danielsen, Finn; Ottersen, Geir & Beszczynska-Möller, Agnieszka [Show all 10 contributors for this article] (2021). Data Management Plan V2. INTAROS project. Full text in Research Archive Show summary

  This document contains the Data Management Plan (DMP) for the INTAROS project. The DMP describes how new datasets collected or generated by partners in the project, are managed according to guidelines for FAIR data management in Horizon 2020. This includes the procedures for planning and conducting data management within the project, i.e., the data governance framework. Data governance in INTAROS is pragmatic and geared towards supporting partners in preparing and publishing their data collections.

• Jelmert, Anders; Sandø, Anne Britt; Frie, Anne Kirstine Højholt; Bogstad, Bjarte; Grøsvik, Bjørn Einar & Eriksen, Elena [Show all 50 contributors for this article] (2020). Status for miljøet i Barentshavet: Rapport fra Overvåkingsgruppen 2020. Havforskningsinstituttet. Full text in Research Archive Show summary

  I rapporten dekkes tre hovedtemaer: (1) Dominerende trekk i status og utvikling i økosystemet i Barentshavet siden 2016 med vekt på å beskrive hvordan sentrale prosesser påvirker tilstanden; (2) en mer detaljert beskrivelse av status og utvikling for de ulike komponentene i økosystemet; og (3) en beskrivelse av fiskeriforvaltningen i Barentshavet.

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