Genes of Turquet’s octopus hold memories of melting of previous Antarctic ice sheet, raising fears of what another thawing could bring
with fears that global heating could soon push it towards runaway melting that would lock-in rising sea levels over centuries.
In an ingenious approach, a team of 11 scientists – including biologists, geneticists, glaciologists, computer scientists and ice-sheet modellers – looked at the genetics of Turquet’s octopus – a species that has been living around the Antarctic continent for about 4m years.The octopus DNA carries a memory of its past, including how and when different populations were moving and mixing together, exchanging genetic material.
“That could only have happened if the ice sheet had completely collapsed,” said Dr Sally Lau, a geneticist at James Cook University who led the research., Lau said, because she wanted the scientific community to have early access and because of the urgent nature of the findings. She said information on the changes in the DNA of the octopus can be used like a clock, allowing her to pinpoint the period when octopuses in the south Weddell Sea and the Ross Sea were mixing.Prof Nick Golledge, a co-author of the research from Victoria University of Wellington in New Zealand, said a major concern was that once the ice sheet reaches a tipping point, the melting becomes “self-sustaining” and would continue for centuries or longer.
He said the route the octopuses are thought to have used is about 1,500 to 2,000 metres below the top of the current ice sheet. That channel would have been about 1,000 metres deep, but shallower nearer the edge.He said over the past two decades, the rate of ice loss from westAccording to the most recent UN climate assessment, temperatures during the last interglacial were between 0.5C and 1.5C warmer than the period just before the industrial revolution.