If the West Antarctic Ice Sheet collapsed, it could raise seas by 16 feet (5 meters), which would be disastrous. Thankfully, we're not at that point yet, but if the Earth's climate keeps warming and nothing is done to stop it, we could eventually have to face such a catastrophe. It's not as far-fetched as some would have us believe, as new reserach into octupus genetics (of all places) is providing new evidence that just such a thing might have happened in the relatively recent past, possibly as recently as 200,000 years ago (which is pretty recent compared to the age of the Earth, which is approx. 4.54 billion years).
A team of scientists analysed the genes of the Turquet's octopus, which lives in the Southern Ocean surrounding Antarctica. During the Census of Antarctic Marine Life, which ran from 2005 to 2010, and International Polar Year, teams of scientists collected Turquet's octopuses from all around the continent.
Adult Turquet's octopuses only move to escape from predators. This means they tend to stay put and don't travel very much at all. So the researchers expected octopuses from different regions of Antarctica to be genetically quite dissimilar.
But to their surprise, they found that the genes from octopuses taken from the Weddell and Ross Seas, on the opposite sides of Antarctica, were startlingly similar.
'The Ross and Weddell Seas are completely separate: they're about 10,000 kilometres apart,' says Strugnell. 'So we expected the genetics of these octopuses to be quite different.'
When the climate was much warmer, sea levels would have been substantially higher, because less water would've been locked up as ice. In this situation, the Ross and Weddell Seas could have been connected.
'Ocean currents would have both facilitated and hindered the flow of genes. But the Antarctic Circumpolar Current almost certainly wouldn't have facilitated so much dispersal by octopuses that two populations have almost identical genetics,' Strugnell says.
'So, we think this would only have happened if the West Antarctic Ice Sheet had collapsed.'
In contrast, Turquet's octopuses from other parts of Antarctica showed the level of genetic differences that Strugnell and her colleagues were expecting, so this if further evidence that West Antarctica's ice sheet could have collapsed.