Arctic Invasion: Historical Period Reveals Ice-Free Conditions in the Arctic Ocean Due to Atlantic Plankton Invasion
A study published in Nature Geoscience presents an analysis of sediment cores, indicating that during the Last Interglacial, a time in the Earth’s history about 129,000 to 115,000 years ago, a species usually found in subpolar areas linked to Atlantic water significantly extended into the Arctic Ocean. This suggests that the Arctic encountered summers without ice cover during that era. The disappearance of Arctic sea ice due to climate change has prompted researchers to examine the past for insights into ice-free conditions.
Flor Vermassen, a postdoctoral researcher at Stockholm University, explains that the Last Interglacial is a noteworthy era to study because it represents a time when global temperatures were potentially similar to or higher than current levels, and sea levels were notably elevated. However, there’s been disagreement about the extent of sea ice during this period, hindering comprehension of this timeframe and the ability to simulate it in climate models.
To address this gap, a team from Stockholm University’s Department of Marine Geological Sciences investigated sediment cores from areas beneath today’s thickest Arctic ice regions. By analyzing the microfossils, specifically planktonic foraminifera, the researchers documented a substantial spread of the subpolar Atlantic species Turborotalita quinqueloba into the central Arctic Ocean. This expansion aligns with the preference of T. quinqueloba for ice-free, productive waters similar to those in the Atlantic Ocean. This finding draws parallels between the Last Interglacial’s absence of summer sea ice and increased influence of Atlantic currents in the Arctic and current processes known as ‘Atlantification’ of the Arctic Ocean.
Flor Vermassen emphasizes the concern that the Arctic Ocean was ice-free during the Last Interglacial despite only being around 1.5°C warmer than pre-industrial levels, which is comparable to the goals of the Paris Agreement. This period had significantly higher sea levels than today. Consequently, the researchers propose the Last Interglacial as a relevant epoch for understanding a seasonally ice-free Arctic Ocean, especially if the Paris Agreement targets are not surpassed.
Vermassen suggests that comprehensive comprehension of the Last Interglacial’s Arctic conditions requires additional quantitative proxy reconstructions of sea-surface temperature and related parameters, along with targeted climate and oceanographic modeling of that timeframe. The study received funding from the Swedish Research Council.
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Frequently Asked Questions (FAQs) about Interglacial Arctic Ocean
What does the study reveal about the Arctic Ocean’s past?
The study uncovers that during the Last Interglacial, a period around 129,000 to 115,000 years ago, the Arctic Ocean experienced ice-free summers due to the expansion of a subpolar Atlantic species.
Why is the Last Interglacial significant for research?
The Last Interglacial is crucial for study because it offers insights into a time when Earth’s temperatures were comparable to or higher than current levels, and sea levels were considerably elevated.
What method did researchers use to study this period?
Researchers examined sediment cores from areas beneath today’s thickest Arctic ice regions and analyzed microfossil content, particularly focusing on planktonic foraminifera.
What species expanded into the Arctic Ocean during this time?
The subpolar Atlantic species Turborotalita quinqueloba extended into the central Arctic Ocean, indicating the influence of ice-free, productive waters.
How does this relate to current Arctic changes?
The absence of summer sea ice and increased Atlantic currents mirror contemporary processes referred to as ‘Atlantification’ of the Arctic Ocean.
What are the implications for climate change?
The findings raise concerns about the Arctic being ice-free even with a relatively small temperature increase, highlighting potential sea level rise.
Why is the Last Interglacial suggested for further investigation?
Given its relevance to the Paris Agreement objectives, the Last Interglacial provides a valuable context for understanding an ice-free Arctic Ocean.
What additional research is suggested?
To better understand the Last Interglacial’s conditions, researchers recommend quantitative proxy reconstructions and modeling of sea-surface temperatures and other water mass parameters.
Who funded the study?
The study was funded by the Swedish Research Council.
More about Interglacial Arctic Ocean
- Nature Geoscience: A seasonally ice-free Arctic Ocean during the Last Interglacial
- Stockholm University Department of Marine Geological Sciences
