As its snowiest regions heat up beyond recognition, the Earth, which has historically been thought of as a globe with ice caps at either pole, is swiftly losing its reputation as a chilly planet. Because of this, scientists working to comprehend the future of the globe must give top attention to forecasting the increasingly impending effects of global warming. And nowhere is this more crucial than in Antarctica, the lily-white butt of the planet.
According to a report that was published in the journal Nature Communications, “Antarctica is undoubtedly the most sensitive polar region to climate.” West Antarctica has become one of the world’s fastest-warming regions between 1958 and 2010, increasing by 2.4 1.2°C (4.3 2.2°F).
And in order to understand what that means for the southernmost continent on Earth, the study’s authors—a multinational team composed of teams from Germany and Australia—have looked to the past. In truth, it was a very long time ago. The oldest marine DNA ever found was hidden in the deep-sea sediments of the Scotia Sea, just north of Antarctica, and was found using a novel method known as sedimentary ancient DNA (sedaDNA) analysis.
According to Dr. Linda Armbrecht, the study’s lead author from the University of Tasmania in Australia, “this represents by far the oldest documented marine sedaDNA to date.” The DNA is older than the two previous record-holders combined, which were 650,000-year-old permafrost deposits from Siberia that were analyzed earlier this year and 400,000-year-old cave sediments found in 2003.
However, as great as it sounds, it may not actually be the most significant finding of the study. The 500,000-year-old remains of diatoms, a form of phytoplankton that inhabited the region during one of its warmer eras, are a considerably more recent contender for the title.
In actuality, a wide range of this phytoplankton were discovered to be abundant: “peak diatom abundance [was confirmed] between 12.7 and 11.3 [thousand years]… i.e., during the latest glacial termination’s Antarctic Cold Reversal, the scientists write.
The researchers discovered a fundamental change in the prehistoric marine ecology that coincided closely with earlier instances of abrupt warming. During the previous warming era 14,500 years ago, the proportion of diatoms among eukaryotes—organisms with membrane-bound nuclei—shot from one in ten to one in two, and this are thought to have contributed to a substantial rise in ocean productivity near Antarctica.
Paleoceanographer and research co-author Dr. Michael Weber of the University of Bonn in Germany said, “This is an interesting and crucial change.” Due to natural warming, “[it] is coupled with a worldwide and rapid rise in sea levels and catastrophic loss of ice in Antarctica.”
Success of the study demonstrates that very new and unproven methods of monitoring the biological world around us, like sedaDNA, can be useful instruments across very long durations, opening up a wide range of possibilities for paleoceanographers and climate researchers.
The scientists note that the examination of sedaDNA “has immense potential to go beyond typical environmental proxies and allow reconstruction of entire ecosystems” because genetic evidence of all animals, fossilizing and soft-bodied, may be maintained in sediment records. Although only minimal amounts of DNA are maintained, they are fragmented and degraded, making sedaDNA susceptible to contamination from contemporary environmental DNA. As a result, recovering sedaDNA is challenging.
The doors are now, however, wide open. Our results, they write, “are important for paleoecology because they extend the temporal window of using sedaDNA analysis as a marine paleo-environmental monitoring tool from 140 [thousand years] to 1 [million years], i.e., covering several glacial-interglacial cycles.”
Environmental DNA analysis, of which sedaDNA analysis is an example, has already demonstrated its end-of-the-world prowess in the fields of pandemic prevention and endangered species conservation. Global warming and the potential post-ice age planet we may soon inhabit are maybe a logical progression from that outstanding resume.
