Queensland scientists believe looking at the ancestry of sea snails could give an early warning about whether part of Antarctica is in danger of collapse, potentially causing a massive rise in global sea levels.
The West Antarctic Ice Sheet contains 2.2 million cubic kilometres of ice, or around 10 per cent of the total of Antarctica’s ice, however it did not exist 125,000 years ago.
At that time the global temperature was just one degree higher than it is today, but sea levels were up to nine metres higher than they are currently.
Associate Professor Jan Strugnell, from James Cook University, said as much as five metres of that could have come from the WAIS.
“That’s really critical, because around 200 million people live in areas up to just one metre above the current sea level,” Professor Strugnell said.
“So it’s really important looking into the future to get the most accurate predictions of sea level rises as we can and try to plan and develop policy.”
However researchers did not know whether the WAIS was intact 125,000 years ago.
Attempts to use traditional geological and ice sheet modelling approaches have been inconclusive.
Enter the mollusc.
Professor Strugnell says if the WAIS did not exist at that time, Antarctica would not have been a single frozen continent, as it was today, but a series of rocky islands with seaways between them.
“So just like people these days like to do a genetic sample of themselves to find out more about their ancestry, we can take samples of the animals that live around the sea floor of Antarctica today and use that to get a picture of what happened in the past,” she said.
“What we’re looking for is similar genetic types on either side of the continent, and if that’s the case, that suggests those animals were able to move across Antarctica at a time in the past.”
Scientists could use the rate of evolution of DNA as well as the fossil record to determine the sea creature’s family trees with reasonable accuracy, giving them a reliable guide to whether the seaway was open 125,000 years ago.
If it was, that would indicate the WAIS could be due for another collapse, causing a similar rise in global sea levels.
“It points towards the West Antarctic Ice Sheet being quite sensitive and vulnerable to melting,” Professor Strugnell said.
The latest IPCC report from the UN indicated global sea levels could rise by up to a metre by the end of the century, however another paper published this week by the journal Proceedings of the National Academy of Sciences indicated that estimate could be conservative, and did not take into account increasing ice melt from Antarctica.
The James Cook University team has taken the samples it needs and will now analyse them to find out whether the ice sheet collapsed in the past, and whether it could do so again.
Professor Strugnell appreciated the irony of a university based in tropical north Queensland researching the icy southern pole, but said those differences would not matter if their hypothesis proved correct.
“Sea level rises affect us all, and it doesn’t matter that I’m based in Townsville, my house is still a little too close to the sea,” she said.