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Home » Microfossils reveal Arctic Ocean was ice-free during last interglacial

Microfossils reveal Arctic Ocean was ice-free during last interglacial

During the Last Interglacial, a subpolar species associated with Atlantic water extended far into the Arctic Ocean, suggesting ice-free summers in the region. This significant change is crucial to study as it can provide insights into a world without Arctic sea ice due to the current climate warming and potential future disappearance of summer sea ice.

Researchers from Stockholm University analyzed sediment cores from locations beneath the thickest parts of the modern Arctic ice pack to understand the microfossil content, particularly focusing on planktonic foraminifera. This research aims to shed light on the climate dynamics during the Last Interglacial period, which had global average temperatures similar to or even higher than the present and considerably higher sea levels. Despite intense debates and lack of consensus on the extent of sea ice during that time, this study can contribute to a better understanding of the past and aid in simulating it accurately in climate models. The findings have been published in Nature Geoscience, providing valuable information for climate research and predictions.

Scanning electron microscope images of the planktonic foraminifer Turborotalita quinqueloba. Scale bars = 100 micron. Credit: Stockholm University

The researchers made a significant discovery during their study, as they found a substantial increase in the abundance of the subpolar species Turborotalita quinqueloba in the central Arctic Ocean during the Last Interglacial. This expansion suggests that the species followed similar conditions from the Atlantic Ocean, which were predominant in ice-free and seasonally productive waters.

The absence of summer sea ice and the stronger influence of Atlantic currents in the Arctic during that time resemble the current “Atlantification” of the Arctic Ocean, observed in some areas today.

The implications of their findings are concerning, as the Last Interglacial period's temperature was only about 1.5°C higher than pre-industrial levels, aligning with the Paris Agreement's temperature targets. However, global sea levels were significantly higher than they are currently.

Given the relevance of the Last Interglacial period and its potential insights into a seasonally ice-free Arctic Ocean, the researchers propose it as a crucial epoch for studying if the goals of the Paris Agreement are to be met.

To gain a comprehensive understanding of the conditions in the Arctic during that time, the researchers highlight the need for additional quantitative proxy reconstructions of sea-surface temperature and other water mass parameters. They also emphasize the importance of conducting targeted climate and oceanographic model studies for the Last Interglacial period. This approach can provide deeper insights into the climate dynamics and of that unfamiliar Arctic era.

Source: Stockholm University

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