Coastal cities not safe from sea level rise warns oceanographer

Cosmos Magazine


Cosmos is a quarterly science magazine. We aim to inspire curiosity in ‘The Science of Everything’ and make the world of science accessible to everyone.

By Cosmos

Video image

A leading Australian oceanographer says Australia’s coastal cities, including Sydney, are “not viable” under high-end projections of future sea level rise from global warming.

Professor Matthew England from the Centre for Marine Science & Innovation at the University of NSW, (UNSW) and Deputy Director of the ARC Centre for Excellence in Antarctic Science, says nobody “built up a city around the world’s coastlines expecting it to be gone in a couple of hundred years.”

England says sea level rise could breach through five meters in a “couple of hundred years.”

“That’s at the high end of the scenarios. But to know that some of our major coastal cities are not viable in their present form, at that rate of sea level rise, is confronting.”

England was recently part of a UNSW team evaluating the potential of a collapse in the Antarctic Meridional Overturning Circulation. This Antarctic overturning has a counterpart in the Northern Hemisphere which is forecast to collapse before the end of this century. In studying the Antarctic overturning, the team modelled the impacts of a warming climate on ocean flow for the next 50 years.

“That science we undertook was actually a multi-year project. I first had the idea to go and look at model simulations configured this way probably about 10 years ago.

“And when we got to run the simulations, they were so costly on the supercomputers we have in Australia. Even the very best supercomputers in the world would require a couple of years to crunch through the full set of simulations. So it was a slow process, and we saw those results come to bear over that time. This slowdown of the circulation and running those simulations through to 2050 actually took us a full year of computer time to see some initial results.”

England was talking about climate change while filming video content for Cosmos.

“Antarctica is a unique continent. It locks up, in the frozen ice, [more than] 50 meters of global sea level. And what I mean by that is if we go back to the Eocene period, back 50 million years, we can get back to a time when Antarctica had virtually no ice on it.

And we know that through geological records, sediment records, we know that sea levels were 50 meters higher than today. We can also do a volume measurement.  It’s easy to do a budget of the ice and know that melting the entirety of that ice sheet would raise sea levels by 50 meters.

“We don’t think all of that 50 meters is unstable to climate change.

“But we are particularly worried about the West Antarctic ice sheet, which locks up about five to seven meters of sea level rise.

England image cropped
Matthew England (Supplied)

“Parts of East Antarctica also look vulnerable. So the fact that a lot of that 50 meters is going to be stable to climate change isn’t cause for comfort because we know there’s at least five and as much as about 10 meters that could be destabilized in the long term because of our emissions of carbon dioxide in the atmosphere.

“I think there’s not really this awareness that the scientific community would like there to be.

“It is very frustrating as scientists and it’s been frustrating for 30 years now, to see this campaign against the science. I mean, the physics of climate change were pretty much established in the 1960s. By the 1960s, we knew ongoing greenhouse gases would pose a real problem for climate change.

“And the scientists have been packaging reports on this. IPCC reports, publications, we’ve been in the media, we’ve been campaigning for a reduction in fossil fuel burning, and we need to go to net zero now because we’ve left things so late.

“There’s an urgency there. So it is deeply frustrating to have the science sitting here, being ignored. It’s patently clear, the physics of ocean warming is actually high school physics and to have elected leaders at times dismissing climate change as a non-issue, it makes you angry.

“I’ve heard elected leaders say climate science is fraudulent. That climate change scientists, are frauds. I mean that’s beyond frustrating. It makes us incredibly angry as scientists to put this hard work into discovering the truth of the physics of the oceans and the climate system, and to have it somehow slammed as junk science, is maddening.”

“It is a personal journey, being an oceanographer. Our climate is changing so rapidly. I don’t think that my kids will necessarily have much of the barrier reef alive when they are my age. When they grow up and have their own kids, they won’t be lucky enough to go and see the beauties of the coral reef along the Queensland coast.

The impact of sea level rise

“A lot of it is bleaching already. We don’t expect it to be robust to 2°C warming. We’re headed to those temperatures now, starting from the northern reaches. Progressively southward bleaching will occur and take out that reef.

“And so yeah, it’s personally confronting to be part of because we’re seeing our oceans change in profound ways. And I know that people born today will grow up and live with a different ocean to the one that I grew up with as a kid.

“The wheels need to fall off the fossil fuel industry. It’s been subsidized for too long. It’s a dirty way of creating energy. It warms our planet. It creates a debt to future generations that is vast in cost and we need to dump fossil fuels and abandon them.

“And once that tipping point comes in how we produce energy, we’ll get to net zero and we can start worrying about some of the adaptation we’ll need to have. Because unfortunately, we’ve virtually certainly already locked in a couple of degrees Celsius of warming.

“And even that level of warming is going to be costly to humans.”

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