The future Arctic Ocean: projections, processes, implications, and uncertainties
This plenary starts with two keynote talks that provide a more general understanding on how the future Arctic Ocean may look like. The keynotes will be followed by oral presentations on more specific topics.
09:00-09:30 Keynote talk 6: The future Arctic sea ice: Key drivers and regional variabilities Marius Årthun (University of Bergen, Norway)
10:00-10:15 Oral Presentation Future Arctic Ocean 1: Assessing the Spread of Atlantic Water Layer Temperature and Salinity in the Arctic Ocean in CMIP6 Model Ensemble Members Devilliers M*, Olsen SM, Yang S, Langehaug HR
11:15-11:30 Oral Presentation Future Arctic Ocean 4: How can Functional Groups be Affected by Low and High Carbon Emissions Scenarios in the Barents Sea? Nascimento MC*, Pedersen T, Fransner F, Primicerio R, Hordoir R, Skogen M
11:30-11:45 Oral Presentation Future Arctic Ocean 5: Integrative Studies for Assessing Diversity, Distributions, Trophic Role and Range Shifts of Jellyfish in Tomorrow’s Arctic Ocean Havermans C*, Dischereit A, Murray A, Pantiukhin D
Session content: Nowhere is climate change more evident than in the Arctic with an unprecedented loss of sea ice and warming at more than twice the global rate. A warmer and ice-free Arctic Ocean could have cascading effects on weather and climate over mid-latitudes, the Atlantic meridional overturning circulation, and marine ecosystems. A visible manifestation of Arctic climate change is the poleward penetration of warm Atlantic and Pacific waters and biota. This encroaching borealization of the Arctic Ocean represents an essential step towards a new Arctic climate state and ecosystem. All of these changes are rapid, complex, and little understood, as the Arctic Ocean is both poorly observed and difficult to model. Nevertheless, this session aims to provide some answers.
¹Alfred Wegener Institute for Polar and Marine Research, Bremerhaven, Germany, ²UiT The Arctic University of Norway, Tromsø, Norway, ³Norwegian Polar Institute, Tromsø, Norway, ⁴British Antarctic Survey, Cambridge, United Kingdom
In the Arctic the warming already leads to fundamental changes, and projections for the future indicate them to intensify further. Arctic PASSION (EU funded) aims to support the co-creation and implementation of a more coherent, better integrated, and more useful Arctic observing system. We aim to overcome known flaws in the present observing system by refining its operability, improving, and extending pan-Arctic scientific and community-based monitoring and the inclusion with Indigenous and Local knowledge. Arctic PASSION has a pan-Arctic ambition and collaborate with other internal projects and programmes to forward the work on a future Arctic observing system on many levels. This includes how to shape an observing system to allow a monitoring of the most relevant environmental changes, the provision of data to improve numerical predictions and to serve decision making. We will present the status of the Arctic PASSION work in terms of improved coordination and enhanced observations, improving the Arctic data system, the use of modelling to support observational design, policy and decision-making support, and the development of services to cover relevant information needs regarding food security, emergency preparedness, wildfire and pollution risk reduction, environmental change information, infrastructure, transport, and safe shipping. We will also present our current understanding of Arctic Observing system elements needed for serving society's need in the future Arctic.
¹Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, Bremerhaven, Germany
Gelatinous zooplankton are major drivers of ecosystem changes. Increases in biomass or “jellification” have been observed in several marine ecosystems, causing, amongst other factors, major fishery collapses. For the Arctic region, accurate diversity and abundance data on jellies are virtually non-existent, impeding our ability to detect impacts of a similar magnitude. We study current and future species distributions of dominant Arctic jellyfish under a growing influence of Atlantic waters. To do so, we combine net catches with environmental DNA and optical video systems to provide new information on the drivers of jellyfish distributions in Arctic environments. On these and public datasets, we apply species distribution models to understand species and community patterns and predict changes under climate-change scenarios. Based on predictive modelling, we project an Arctic “jellification” with range shifts of major Atlantic species into the Arctic Ocean on the pan-Arctic scale, and an increase of regional jellyfish abundances. By means of molecular diet studies, we reveal the importance of jellyfish as prey based on molecular diet studies of predator species such as fish and zooplankton predators. Finally, by investigating the species richness, abundances, and trophic role of jellyfish in fjords in which the influence of Atlantic water differs, we set a baseline to detect potential range shifts and predict the impact of jellyfish on local food webs in an Atlantified Arctic.
¹GEOMAR Helmholtz Centre for Ocean Research, Kiel, Germany, ²UiT The Arctic University of Norway, Tromsø, Norway, ³University of Bergen, Bergen, Norway, ⁴Institute of Marine Research, Bergen, Norway
Polar regions are highly affected by the ongoing climate change and are expected to become profoundly different under all warming scenarios. Changes in the Arctic oceans' ecosystem structure and species range shifts are expected. To evaluate the impacts of climate change on spatial distributions of functional groups in the Barents Sea in medium and long term, we simulated three plausible futures climate scenarios using the spatially resolved dynamic mass-balance food web model Ecospace for the Barents Sea (108 functional groups - FGs). We used the downscaled climate scenarios SSP 1-2.6, 2-4.5 and 5-8.5 from NorESM with Nemo NAA 10 km combined with three levels of fisheries exploitation regimes (low, “business as usual”, and high fishing mortalities), running from 2020 to 2100. We applied environmental envelope limitations for many FGs and used environmental drivers such as temperature, ice coverage and phytoplankton primary production for each scenario. The model ran with monthly time steps and input of spatial environmental data. When simulating the scenarios with mitigation of carbon emission (i.e., SSP1-2.6 and SPP2-4.5), even though the FGs shift the distribution polewards for the period 2023-2050, in the long term from 2050-2100, the centre of gravity of the FGs distributions returns closer to the starting point. In the high-emission scenario (SSP 5-8.5), the shift poleward is intensified in the long term (2050-2100).
Present and Future Influence of Ocean Heat Transport on Winter Arctic Sea-Ice Variability
Dörr J*¹², Årthun M¹², Eldevik T¹², Sandø AB²³
¹University of Bergen, Bergen, Norway, ²Bjerknes Centre for Climate Research, Bergen, Norway, ³Institute of Marine Research, Bergen, Norway
The recent retreat of Arctic sea ice is overlaid by strong internal variability on all timescales. In winter, sea-ice retreat and variability are currently dominated by the Barents Sea, primarily driven by variable ocean heat transport from the Atlantic. It is projected that the future loss of winter Arctic sea ice spreads throughout the Arctic Ocean and, hence, that other regions of the Arctic Ocean will see increased sea-ice variability. It is, however, not known how the influence of oceanic drivers on regional winter sea ice variability will change. Using a combination of observations and simulations from large ensembles, we analyze and contrast the present and future regional drivers of the variability of the winter Arctic sea-ice cover using lagged correlations and a causal method. We find that for the recent past, sea ice variability in the Atlantic and Pacific sector of the Arctic Ocean is influenced by ocean heat transport through the Barents Sea and Bering Strait, respectively. Models agree on a gradual expansion of the footprint of the Pacific and Atlantic inflows, covering the whole Arctic Ocean by 2050-2079. This work highlights the combined importance of future Atlantification and Pacification of the Arctic Ocean and improves our understanding of internal climate variability which is essential to predict future sea ice changes under anthropogenic warming.
¹Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung (AWI), Bremerhaven, Germany, ²University of Bremen, Bremen, Germany
Climate change is rapidly altering the whole Arctic system from the atmosphere, the cryosphere, the land and ocean. Here, we focus on the impact of terrigenous inputs, including rivers and coastal erosion, on the Arctic Ocean biogeochemical cycles, using model forecasts. Despite additional inputs of nutrients from land, the Arctic Ocean cannot cope with the massively increasing drawdown by phytoplankton and is inexorably shifting from a light-limited to a nutrient-limited. The cycling of nitrogen is becoming the bottleneck of carbon cycling and the biological carbon pump. If terrigenous inputs did not alleviate nutrient limitation, we show that they contribute more to the intensification of biogeochemical processes, such as remineralization, than scenario uncertainty (a change from a low to a high emission scenario). In a high emission scenario, we found that increased remineralization largely compensates the increase in net primary production, reducing carbon export efficiency and the Arctic Ocean's ability to store carbon.
Assessing the Spread of Atlantic Water Layer Temperature and Salinity in the Arctic Ocean in CMIP6 Model Ensemble Members
Devilliers M*¹, Olsen SM¹, Yang S¹, Langehaug HR²
¹Danish Meteorological Institute, Copenhagen, Denmark, ²Nansen Environmental and Remote Sensing Center, Bergen, Norway
In this study, we present a comprehensive analysis of the spread in temperature and salinity projections among the members of the Coupled Model Intercomparison Project Phase 6 (CMIP6) models, focusing on the Atlantic water layer in the Arctic Ocean. While this layer plays a critical role in the transport of salt and heat within the Arctic Ocean basins, its characteristics are not well represented in climate models, leading to divergent projections of future changes in the Arctic. To address this question, we analyzed a suite of CMIP6 models and assessed the realism of the Atlantic Layer characteristics including variability and trends in the historic period across all the available members in the multi model ensemble. By comparing the model results with available reanalysis, we aim to identify the biases within the model simulations and develop new metrics to constrain the models spread. Such metrics can be used to screen all members in the multi-model multi-member ensemble and construct a subsample with improved representation of the Atlantic water layer in the historical period which can be applied for projection of future changes in the Arctic region with reduced uncertainty.
Travel information for Nansen Legacy scientists
All Nansen Legacy researchers still actively involved in the project should purchase their travel as they have done previously (follow guidelines at their own institution) and apply for travel reimbursements by their respective partner institutions. The institutions will then send a compiled claim to the project office.
For symposium registration, the project administration will soon send you a booking code by email that will allow you to register for the symposium and book the hotel room through the registration system. Accommodation costs and the participant fee will directly be covered by the Nansen Legacy.
Environmental problems are very often tricky problems: they are persistent, many are vast in scale with no clear end, and involve political decisions and struggles that are more about values, world views and ideology than they are about scientific facts. Even if it may seem crystal clear what environmental problems we are facing, the ecological and biological elements on the effect side of these problems are dynamic and complex, and the social and political elements on the solution side are constantly changing. And not the least; looking into the future, the complexity and uncertainty grows even larger. In a rapidly changing world, and in lack of linear patterns from science to action; what does it take to make decisions? Do we have the knowledge and knowledge systems we need to inform complex challenges? In this talk, rather than looking at the barriers I will focus on what I think are enabling factors for efficient uptake of science and knowledge in management and decision-making processes related to climate, nature and pollution.
Keynote Talk 6
Thursday, 9 November 2023 09:00-09:30
The future Arctic sea ice: Key drivers and regional variabilities
Marius Årthun (University of Bergen, Norway)
The Arctic sea-ice cover is currently retreating and will continue its retreat in a warming world. However, the loss of sea ice is neither regionally nor seasonally uniform. Sea ice conditions and associated drivers of variability differ substantially from region to region within the Arctic, and considering only pan-Arctic trends thus masks competing regional trends and makes the underlying drivers and implications difficult to ascertain. Arctic sea-ice loss is also not seasonally uniform. Whereas the overall pan-Arctic sea-ice loss has been largest in summer, the winter trends are of the same magnitude in the southernmost regions, and particularly in the Barents Sea. In this talk, I will detail the seasonal and regional transition to an ice-free Arctic based on observations, large ensemble simulations, and CMIP6 models. The key drivers of present and future sea-ice variability and the relative contribution of internal (natural) and external forcing will be discussed.