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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

Partner countries:

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. We have used these long-lived coralline algal buildups on the shallow Svalbard shelf to reconstruct climate and ice variability for several centuries in the past. By analysing the trace elemental ratios in the coralline samples, we established age models based on the seasonal cyclicity in the geochemistry. A multi-specimen growth chronology has been from Nordaustlandet spanning AD 1818-2020. From a single longer-lived specimen, a single specimen growth chronology was going back extraordinarily 280 years (AD 1740-2020). These new robust sea ice proxy time series provide provide long-sought constraints for climate modeling as well as provides as data that extends the short instrumental time series of sea ice variability in the Arctic making it possible to look at more longer-term features in the dynamics of Arctic sea ice variability.

With the CARA-ICE project we have documented the high potential of using coralline algae as archives of past sea ice variability around Svalbard. We have produced an annually resolved 280 year long record of sea ice variability from Nordaustlandet, which will be available for the research community. This new robust sea ice proxy time series provide provide long-sought constraints for climate modeling as well as provides as data that extends the short instrumental time series of sea ice variability in the Arctic making it possible to look at more longer-term features in the dynamics of Arctic sea ice variability.

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.

Funding scheme:

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