APEAR

Description

The fast decline of Arctic sea ice in the last decades is commonly viewed as manifestation of the climate change. The sea ice reduction exposes a large area of the previously ice-covered Arctic Ocean to the atmosphere, and intensifies air-ocean exchanges of heat, moisture, and momentum. This leads to changes in ocean circulation and water masses, and impacts ocean ecosystems. However due to multiple influences between ocean circulation, supplying of nutrients to biologically productive areas, and sea ice, which controls light penetration in the ocean, the future state of the Arctic ecosystem is not well understood.

APEAR hypothesis

As Arctic sea ice retreats, exchange of Atlantic and Pacific waters across the Lomonosov Ridge is modified due to changes in the air-ice-ocean momentum fluxes. The ocean circulation systems in the Eurasian and Amerasian Arctic may become less coupled, leading to differing pathways of nutrients advected with water masses originating in the Atlantic and Pacific. Whereas the regional differences in the ocean and ecosystems may increase, the prolonged sea ice-free season can moderate the difference between the two provinces in the Arctic through stronger haline convection and through mixing by wind and waves.

Approach

Using historical data, new observations and high-resolution models constrained by the data, APEAR will investigate mechanisms controlling advective fluxes of nutrients and ecologically important key substances, such as CO₂ and dissolved organic carbon (DOC).

We will combine the data analysis with ultra-high-resolution ocean biogeochemical (BGC) modelling to quantify current changes in the Arctic ecosystems and will make use of the unique dataset expected from the “Multidisciplinary drifting Observatory for the Study of Arctic Climate” (MOSAiC), covering a large part of the Eurasian Basin and central Arctic throughout a full seasonal cycle in 2019/2020.

There are additional physical and biogeochemical observations by ship and autonomous drifting platforms from the recent three decades that give the large-scale and long-term context to the MOSAiC observations. These observations are ongoing, in particular, a network of autonomous drifting (ice-based) multidisciplinary observing platforms providing annual to bi-annual coverage of the Eurasian Basin and the central Arctic.

APEAR will examine nutrient supply to the upper ocean and the lower trophic level dynamics with a series of high-resolution coupled atmosphere-sea ice-ocean-biogeochemical simulations. From the synthesis of the data and multi-model Earth-Systems Models (ESM) simulations in the Climate Models Inter-comparison Project (CMIP6), APEAR will provide future projections of the changes in the Arctic biogeochemistry and ecosystems during the 21st century.

These projections will include analyses of model sensitivity and associated uncertainty. They will quantify the impact of the emerging influence of the new Arctic physical climate on the BGC and ecosystems and will help assessment of the impact on the fisheries, Arctic industries and societies.

APEAR brings together leading researchers from the UK and Germany, with the partnership from the Sweden, capitalising on the critical mass of the expertise in the Arctic sea ice, ocean and ecosystems modelling, Arctic physical oceanography and ecosystems, and climate science. It builds upon expertise in modelling, and Arctic observation within the National Oceanography Centre, Alfred Wegener Institute and University of Gothenburg.

APEAR will facilitate a new understanding of the Arctic physical state and BGC in climate modelling groups within the UK, Germany, Sweden, Europe and worldwide. The research outputs from the project will contribute to the UKESM LTS-M and UK LTS-S strategic programmes and ongoing NERC projects. This will significantly reduce uncertainty in the future predictions of ocean and biogeochemistry in the Arctic in IPCC climate assessments.