Arctic sea-ice melt – what the past can tell us about the future
The Arctic is one of the most sensitive areas with respect to the ongoing global warming, and it is experiencing a warming trend that is greater than in any other region of the world. Summer sea-ice cover in the Arctic has decreased drastically in the last decades. These large amplitude changes have been recorded by satellite observations. However, as these satellite records date from only the late 70s, they cover a too short a period to represent sea-ice variability through time. As the documented changes in sea ice happened under human influence, they might correspond to a transient, non-equilibrium state. The pre-industrial baseline of natural sea-ice cover is practically unknown. The IceDynamO project sought to plug this knowledge gap. “It is crucial to understand how the Arctic sea-ice cover changed through time without any human-induced forcing, in order to be able to develop reliable model predictions for the future,” explains Teodóra Pados-Dibattista, who conducted her research with the help of the Marie Skłodowska-Curie Actions programme while she was at the Department of Geoscience of Aarhus University. “My overall objective was to reconstruct the variability of oceanic and sea-ice conditions on the north-east Greenland shelf during the Holocene, the last ca 11 700 years. I wanted to investigate their connection to the Greenland ice-sheet dynamics, ocean circulation and global climate.”
Unravelling the secrets of the Arctic ice
Pados-Dibattista used a sediment core extracted from the seafloor off north-east Greenland to conduct micropalaeontological and geochemical analyses. Proxy data are preserved, physical characteristics of the environment that can stand in for direct measurements. With the help of the obtained data, Pados-Dibattista established a high-resolution, multi-proxy reconstruction of the dynamics and variability of the East Greenland Current and the sea-ice cover off north-east Greenland at centennial resolution throughout the Holocene. Her paper, ‘Holocene paleoceanography of the Northeast Greenland shelf’, explores her techniques further. “The results of the analyses allowed me to infer changes in sea surface and subsurface productivity, subsurface water temperatures, sea-ice conditions and Greenland ice sheet melting over the last ca 9 400 years on the north-east Greenland shelf,” adds Pados-Dibattista.
Possible implications
The results indicate that the north-east Greenland shelf experienced a series of palaeoclimatic changes during the Holocene, shown by changes of the East Greenland Current. “As our results improve our ability to estimate the future responses of Arctic water masses to environmental changes, they are highly relevant for the improvement of predictive climate models. “This project provided me a unique opportunity to study the northernmost near complete Holocene marine sediment record along the east Greenland margin. To achieve this I had to learn, right from the start, how to differentiate and identify almost 100 different benthic foraminifer species. This wasn’t an easy ride, but it was all worthwhile,” Pados-Dibattista concludes.
Keywords
IceDynamO, Arctic, sea ice, climate, reconstruction, north-east Greenland shelf, foraminifer
