Though it may seem strange to consider, octopuses—the strangest of all creatures—may be able to provide information about Antarctica’s ice sheets. Scientists have analyzed the genes of a particular species of tentacular cephalopods that inhabit this frigid habitat in a recent study, and their findings are concerning.
The Turquet’s octopus, a population of geographically isolated octopuses, mated freely approximately 125,000 years ago when the three seas surrounding the continent were connected by a transient ice corridor, according to the paper. Global temperatures were comparable to what they are today during this period.
The findings imply that the West Antarctic Ice Sheet (WAIS) might be collapsing sooner than previously believed. The world map as we know it would be drastically altered if this massive marine-based ice sheet were to collapse, raising global sea levels by 3.3-5 meters (10.8-16.4 feet).
The authors argue that if global warming caused by humans is not contained to the 1.5 degrees Celsius target outlined in the Paris Agreement, that is the most likely course of events.
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The group’s research is original. Lead author Sally Lau of James Cook University in Australia told AFP, “I understand and then apply DNA and biology as a proxy of changes to Antarctica in the past.” Lau is an evolutionary biologist who specializes in marine invertebrates.
In particular, the Turquet’s octopus (Pareledone turqueti) was a prime candidate for this research because it is a species that inhabits the waters surrounding the continent and our knowledge of it is extensive, having known about its origins (roughly 4 million years ago) and lifespan (12 years).
This species of small octopus, which is about half a foot long, or 15 centimeters without arms, was able to interbreed for thousands of years when the ice sheet first broke. The animals were then separated once more when the ice reformed. Their distinct genes contain the story of their relationship and separation.
The DNA of 96 samples of Turquet’s octopuses, which were gathered from animals that had been inadvertently captured by fishing vessels and kept in museums for 33 years, was sequenced by Lau and associates.
They discovered evidence of trans-West Antarctic seaways connecting the Ross, Amundsen, and Weddell seas during their investigation, indicating that the WAIS had collapsed twice. The first occurred between 3 and 3.5 million years ago, during the mid-Pliocene era, and the second occurred between 129,000 and 116,000 years ago, during the Last Interglacial.
“This was the last time the planet was around 1.5 degrees warmer than pre-industrial levels,” said Lau.
The burning of fossil fuels has been the main cause of human activity-induced global temperature rise of 1.2 degrees Celsius since the late 1700s.
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The results were far from definitive, even though there is additional evidence that the WAIS has collapsed in the past. That is, up until this point.
“This study provides empirical evidence indicating that the WAIS collapsed when the global mean temperature was similar to that of today, suggesting that the tipping point of future WAIS collapse is close,” according to the paper’s authors.
Even with the seriousness of their findings, there are still some unresolved issues in the study. First off, it’s unclear if temperature variations were the only factor in the old ice sheets’ collapse. Could the intricate relationship between ice and solid ground as well as variations in ocean currents be factors? Furthermore, it’s unclear if the resulting sea level rise would occur quickly or gradually over a longer time frame.
Nevertheless, the outcomes are important to take into account in light of climate change. In an accompanying commentary, geoscientists Robert DeConto of the University of Massachusetts, Amherst, and Andrea Dutton of the University of Wisconsin–Madison stated, “This latest piece of evidence from octopus DNA stacks one more card on an already unstable house of cards.”
Commentators claim that this most recent study is “pioneering” and that it raises the most important question of all: will the past repeat itself?