ATTRACTION

Since satellite-based measurements began in 1978, Arctic Sea ice extent has strongly declined. This is especially pronounced at the Atlantic-Arctic boundary where warm and salty waters of Atlantic origin are progressively replacing the Arctic halocline layer. This phenomenon, known as Atlantification of the Arctic Ocean, has large-scale impacts on several environmental and economic aspects including retreat of the tide-water glaciers, stability of slope gas hydrates, sea ice loss and fish stock. The common perception is that

this process is exclusively limited to modern times, essentially because instrumental evidence has only been available since the last decades. However, our understanding of recent changes cannot overlook the assessment of the past climate evolution. Earth’s

natural climate variability in fact provides a necessary context to evaluate anthropogenic impacts. The last millennium is a critical time window as the abundance of historical documents allows to constrain the range of uncertainty about the climate evolution. Available archives indicate that, during this period, the North Atlantic subpolar circulation experienced remarkable changes, which surely affected the way heat and nutrients are redistributed further north. Considering that similar changes are projected in future scenarios, knowing how subpolar dynamics affected the Arctic gateway in the recent past is an essential step to build confidence on the evolution of the Arctic Ocean. However, a survey of the recent literature covering the Common Era shows that the available marine records are located far too south to capture the expansion of the Arctic-Atlantic front which, in turn, hampers a rigorous validation with paleoclimate simulations.

ATTRACTION acknowledges this limitation and proposes to analyse new archives from a strategic region of the Arctic bathed by the Atlantic inflow to (i) provide novel data on sea-ice dynamics and seawater properties throughout the last millennium and (ii) compare

these proxy-based reconstructions with ensembles of state-of-the-art paleoclimate and historical simulations to identify robust subpolar-polar connections.

In addition, as each earth science discipline dealing with the Atlantification has been primarily working within its restricted circle with a limited exchange of data, ideas and approaches, ATTRACTION will leverage on the diverse nature of the consortium for a mutual enrichment via an interchange of knowledge among physical oceanographers, paleo-oceanographers and numerical modellers.

By combining novel evidence from sediment cores with model results, both validated by modern observations, we will shed new insights into the nature of Atlantification and we will benchmark the ability of models to simulate Atlantification. ATTRACTION will ultimately assess our current capability in predicting future evolution in a region which is expected to face some of the most dramatic changes on Earth in a global warming scenario.