In early 2020 the World Meteorological Organization warned that the volume of ice shed annually from Antarctica had increased at least sixfold since 1979. The 14-million-square-kilometre continent that locks up 90 per cent of the world’s fresh water in its frozen form is slowly melting into the Southern Ocean.
Scientists, understandably, are getting used to grim news from the great white south. Yet the latest Antarctic bulletin managed to take Matt King, the University’s Professor of Polar Geodesy (the science of measuring the Earth’s dimensions) and Director of the Australian Centre for Excellence in Antarctic Science, by surprise.
“Extremes are continuing to emerge on top of the background of existing trends,” he says.
“In March 2022 a 40-degree Celsius heatwave was measured on the Antarctic Plateau at about 3,000 metres above sea level: the coldest place on Earth.
“It wasn’t 40 degrees, of course; but it was 40 degrees warmer than normal. The temperature for most of that vast area still didn’t get above freezing but imagine if Hobart, Sydney or Canberra experienced temperatures 40 degrees above normal for a few days.
“A few days after this year’s central Antarctic heatwave a fortunately inconsequential piece of floating ice broke up after it had been retreating for decades – nonetheless, it was a pretty dramatic event. And this year the coverage of sea ice around Antarctica will shrink to another record low. It’s shocking.”
King, whose academic disciplines marry surveying and glaciology, hopes his work will ensure there are fewer nasty surprises in polar science.
“We get caught by surprise because we don’t know enough. We need to get ahead of those surprises so that we have enough knowledge to predict the future with greater levels of confidence.”
Almost a quarter of the rapidly thinning West Antarctic ice sheet is believed to be unstable, and satellites have revealed that the East Antarctic ice sheet – the larger of the two – is increasingly vulnerable. The frozen continent is contributing about 100 billion tonnes a year to sea-level rise, although it varies from year to year. A burning question for King is the determination and measurement of precisely what in the climate system is causing ice loss.
“Most people would say it’s just climate change, but we don’t yet have a really tight connection between climate change and how the ice sheet responds to climate variability.
“That piece of the puzzle is yet to be resolved, though we’re getting close to saying what changes we’re seeing in the ice sheet are due to climate change, and what’s coming from shorter-term changes due to La Niña and El Niño.
“The ocean is the big story here,” he says.
“Later this year University scientists will be going to the northern edge of the sea ice on RSV Nuyina, CSIRO's new icebreaker, to study the retreating ice and the explosion of biological activity that occurs as more sunlight gets into the ocean. These microbial algae at the bottom of the food chain go berserk in that kind of environment, and as they grow they absorb carbon dioxide. While these are scientifically interesting processes, they matter to all of humanity and we see it as our job to understand them.
“The role Antarctica will play in the climate system of the future will be a balance of many things – some positive contributors, some negative. We don’t understand them all. We know that the Southern Ocean has been absorbing huge amounts of heat and carbon dioxide that would have otherwise been in the atmosphere.
“The fact that the Southern Ocean has been absorbing heat has been a good news story. It’s been a bulwark against more dramatic climate change. But as it continues to absorb heat more of it gets to the ice sheet and starts to melt it. So it’s not going to be a good news story forever.”
Born in Burnie, King moved to Hobart's neighbouring suburb of Glenorchy as a teenager. His first degree in Surveying and Spatial Science was from the University of Tasmania. He began his research career studying glaciers with the help of precise satellite positioning technology before moving on to the study of bedrock and its response to liberation from retreating ice.
“As a glacier melts, all of that solid mass rebounds. In different parts of the earth, it has rebounded two or three centimetres year, and in some parts of Antarctica, that rebound is occurring so fast that it actually slows the retreat of the glacier. It’s one of those complications we need to know more about.”
As a result of these changes the earth itself, he says, is changing shape.
“My team and I are interested in the how and why of Earth’s changing shape. We now have data from more than 15,000 Global Navigation Satellite Systems receivers (such as GPS) around the planet that are connected to bedrock.
“This information can be analysed to estimate millimetre or even sub-millimetre displacements of the Earth. Through these exciting observations we can watch Earth ‘breathe’ as it changes shape in response to water and ice moving around its surface, and earthquakes, and gravitational forces from the sun and moon. Knowing how and why the Earth changes shape is a key to understanding and quantifying the past and future of sea-level rise globally, as well as changes in the great ice sheets of Antarctica and Greenland.”
He regards the University of Tasmania as the best place in the world to do Antarctic and Southern Ocean research.
“When combined with CSIRO and the Australian Antarctic Division it’s an incredibly rich environment.
“Loads of universities have an interest in climate change, but here at the University of Tasmania we live and breathe it, and everyone – including the senior leaders - know we’re uniquely placed to make a difference to the planet.”
King is far from an unimpassioned scientist. Emotion seems to catch in his voice when he speaks of the need to thoroughly map the ocean floor around Antarctica for the presence of “grand sea canyons” whose presence might influence the pace of ice-sheet loss.
“There’s a huge amount to explore,” he says. “There are areas where we know almost nothing.”
When talking of the imperative for deeper knowledge of the polar environment, his cadence quickens.
“I really feel as a global community we haven’t progressed our knowledge fast enough,” he says.
“There’s still too much we don’t know. We know sea levels are rising and that more carbon dioxide will be bad for the world’s climate and bad for the ice sheets, but there are things that prevent us from getting a tight fix on the future and that’s basically lack of knowledge. I feel frustrated that we’re not able to advance that faster.
“We need more sensors in the ocean. We need to go to places that we haven’t been before. We need more people in science. Australia has invested billions in Antarctic research infrastructure – we have a great capacity, great satellite sensors. We now need sustained long-term funding at scale to enable us to maximise the infrastructure we’ve invested in.”
Main image: Drilling for under-ice mapping in Antarctica.
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