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FRINATEK-Fri prosj.st. mat.,naturv.,tek

Establishing Long-term High-Resolution Coralline Algae Records of Arctic-Atlantic Ocean-Sea Ice Variability

Alternative title: Rekonstruksjon av variasjoner i det Arktiske sjøisdekket ved bruk av kalkalger

Awarded: NOK 10.0 mill.

Project Number:

287818

Application Type:

Project Period:

2019 - 2023

Location:

The loss of Arctic sea ice in recent decades is well documented and is one of the most visible manifestations of ongoing climate change. The decline has been most significant during summer, and if current trends persist, prognoses suggest that Arctic summer sea ice may disappear within the next decades. Associated with the decline in sea ice cover is an increase in primary productivity, which partly can be attributable to reduced summer ice areal extent and a longer phytoplankton growing season, which have implications for the ecosystem. These marked changes have generated research interest in the seasonal prediction and predictability of the Arctic climate- and ecosystems. However, sea ice modeling uncertainties are large as long-term, multidecadal, sea ice variability is poorly understood due to short instrumental and satellite records. In the CARA-ICE-project, we will investigate how the poleward propagation of anomalous heat from the subpolar North Atlantic towards the Arctic Ocean affects the sea ice cover in the Arctic-Atlantic on multi-century timescales. We will use crustose coralline algae, a novel marine proxy for sea ice-covered regions that is the only archive known from the Subarctic and Arctic that can achieve this. Long-lived coralline algal buildups on the shallow Svalbard shelf will be used to reconstruct climate and ice variability for several centuries in the past. In CARA-ICE, we will test and quantitatively constrain the degree to which the annual growth and trace elemental ratios of crustose coralline algae living on the Svalbard shelf generally represent the ocean and sea ice in the exceptionally varying site characterized by a confluence of temperate and polar currents and Arctic sea ice. Further, CARA-ICE aims at providing ground-breaking data that will increase the potential for skillful climate prediction in the Arctic-Atlantic. The coralline algae Clathromorphum compactum is a crust-forming algae that lives on rocky shores around the Arctic. Divers collected specimens of C. compactum from areas north of Spitsbergen and along the coast of Nordaustlandet up to Nordkapp during a cruise during the summer of 2020. So far, 80 samples have been prepared to assess the age and quality. We have analyzed the geochemical composition in a total of 4 samples from 2 different localities on Spitsbergen and Northeast Norway.

The primary objective of CARA-ICE is to constrain the role of natural, long-term variability of Atlantic inflow via the West Spitsbergen Current into the Arctic-Atlantic on the radical sea ice loss observed during recent decades. The project aims at providing a definitive breakthrough in our capacity to provide baseline data for the Atlantic sector of the Arctic for the last few centuries. With CARA-ICE we will be able to address several longstanding questions regarding the Arctic sea ice cover that, due to the shortness of the instrumental record, remain unknown. CARA-ICE is a project that takes an innovative approach to understand the multicentury variability in temperature, sea ice and ocean dynamics in the Arctic-Atlantic, an area of research that so far has been inadequately addressed with other proxies by the international research community. In CARA-ICE we will develop and evaluate a multiproxy approach based on coralline algae records to establish natural baseline levels of ocean temperature and sea ice associated with multicentury pre-industrial climatic changes in the Arctic-Atlantic. The methodological approach of CARA-ICE is based on: 1) Developing new sclerochronological and geochemical proxy records using the coralline algae Clathromorphum compactum and 2) Climatic interpretation and statistical analyses. We will test and quantitatively constrain the degree to which the annual growth and trace elemental ratios of crustose coralline algae living on the Svalbard shelf generally represent ocean and sea ice in the exceptionally varying site characterized by a confluence of temperate and polar currents and Arctic sea ice. We will use the Svalbard coralline algae proxy data and other pertinent high-resolution marine records from the subarctic-arctic to quantitatively test whether the multidecadal sea-ice variability that has dominated the Arctic in the instrumental period is a robust persistent feature of the ocean–atmosphere–sea-ice climate system.

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FRINATEK-Fri prosj.st. mat.,naturv.,tek