Climate Change Impact On Antarctica Becomes Clearer As Scientists Make Progress

ABC News - Kate Doyle

Antarctica is thought to hold enough water to increase sea levels by more than 50 metres. (Supplied: Australian Antarctic Division)

Understanding exactly what is going on in Antarctica has long been fraught for climate scientists, but what is happening on the continent could soon be felt around the world.

On the 60th birthday of the Scientific Committee on Antarctic Research (SCAR), there has been a call to arms from top researchers to combat global warming and associated sea level rise before the world's cities are inundated.
According to modern records, Antarctic ice was on average expanding slightly up until 2016, when there was a dramatic decline and levels fell to less than those initially recorded in 1979.
Explaining this expansion and drop has been the work of many scientists who focus on Antarctica.
Steven Phipps, a paleo ice sheet modeller from the University of Tasmania, knows all about the challenges of understanding the great southern continent.
"There is so much uncertainty because we know so little about the Antarctic ice sheet," Dr Phipps said.
"Antarctica is very remote. It is a very extreme environment. We have observations from satellites, but observations on the ground, there are very few."
And there is a lot to not be able to observed.
"The ice sheet is 3 or 4 kilometres of solid ice sitting on rock," Dr Phipps said.
"Actually working out what's happening in terms of the flow processes within the ice, or the melting processes that happen around the edge, they are very hard to observe."

Ice sheet not as stable as first thought
But despite these challenges, Antarctic researchers are making progress.

"One thing we have learnt is the East Antarctic ice sheet, which is where most of the ice is located, is potentially very vulnerable to human-induced climate change, whereas previously we thought it was stable," Dr Phipps said.

By studying past changes, observing the present and using improved modelling, things are becoming clearer.
A new theory published in 2016 by Robert M. DeConto and David Pollard opened the floodgates on the potential sea level rise of the Antarctic.

Matthew England speaks at the 12th International Conference for Southern Hemisphere Meteorology and Oceanography in Sydney on Monday. (Supplied: Scientific Committee on Antarctic Research)

University of New South Wales researcher Matthew England, who was today presented with the $US100,000 Tinker-Muse prize for contributions to enhancing the preservation and understanding of Antarctica, said there was still debate about whether the warming atmosphere or the warming oceans were most responsible for the melt.
"My gut feeling is that the ocean has been the primary reason for the warming. But chat to the atmospheric scientist and they will tell you it's the atmosphere," he said.

Sea level rises will be costly for coastal cities
What produces less debate is that the melt has begun.
On the time scale of this century, which will be in the lifetime of young adults texting away today, sea level rise attributed to just the Antarctic is projected to be about 1 metre.
"Which is already a disastrous level of sea level rise. A metre is enough to be extremely costly," Dr England said.
With the continuing-as-usual emissions scenario, the projected sea level rise from the Antarctic is forecast to be about 15 metres by 2500.
"Which is staggering, because Sydney is not viable at 15 metres of sea level rise," Dr England said.

The ice sheet in Antarctica is 3–4 kilometres of solid ice sitting on rock. (News Video)

The researcher acknowledges we have 200 to 300 years to work up to that, but it will be drastic nonetheless.
"Basically all of the cities we have today, all of them were around 300 years ago," he said.
"We don't build cities and expect to move from them a few hundred years later.
"We need to think about how much of the infrastructure we have tied up on the coast."

'We're not asking people to change much'
Fifteen metres is not even as bad as it could get in the even longer term — the total amount of sea level rise held in Antarctica is thought to be more than 50 metres.
A total melt is not a completely unprecedented scenario — it has all melted before, a long, long time ago.
In the Eocene, lasting from 56 million to 33.9 million years ago, CO2 levels were about four times what they are today and there was no ice over the Antarctic continent.
What can we do?

"It's a call to arms, but we are not asking people to change much. It is just getting behind the renewable sector, getting completely away from fossil fuels because they are the cause of this melt," Dr England said.

"Without action on reducing greenhouse gases … we are going to lock in metres and metres of sea level rise and trillions of dollars of damage."
Dr England describes Antarctic sea level rise as one of the greatest threats to the modern world.
It is hoped his Tinker-Muse prize will help him and his colleagues to better understand what is going on in the mysterious continent to our south.

Links

• Many Of The World’s Coasts Would Become Unviable If Antarctic Ice Continues To Melt Into Sea
• World's top weather, climate and ocean experts meet at UNSW
• Climate change impact on Antarctica becomes clearer as scientists make progress
• Decline in biodiversity as climate change increases ice-free areas on Antarctica
• Rapid greening of Antarctic Peninsula driven by climate change
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