What the world would look like if all the ice melts


It seems Charles Sturt, Thomas Mitchell and other early European explorers tramping the scorching deserts of Australia in search of an inland sea were a few thousand years too early.

According to maps published by National Geographic, Australia will one day get an inland sea if global warming continues and melts the world’s ice caps and glaciers, lifting sea levels by about 70 metres.

The US-based organisation said it would take about 5000 years for all the ice to melt, although impacts will hit coastal communities much sooner – and having an inland sea won’t be much consolation to Australians.

What if all the ice melted? National Geographic's map of a shrinking Australia.What if all the ice melted? National Geographic’s map of a shrinking Australia.

Neville Nicholls, a climate expert at Monash University whose work has included research on Australia’s shrinking snow season, said scientists have known for decades the upper end of sea-level rises from melting the cryosphere would be about 70 metres.

While the complete melting of the world’s ice would potentially take thousands of years, the pace of global warming caused by human activities is putting us on such a course, Professor Nicholls said.

“The amount of warming you need isn’t out of the realms of what we’d expect from business-as-usual emissions scenarios,” Professor Nicholls said.

Europe in an ice-free world.Europe in an ice-free world. Photo: National Geographic

Once you get to warming of about 5 degrees, it would be hard to see how the melting would stop, given the long-lived consequences of a build-up of greenhouse gases, he said.

“You don’t need to wait for 70 metres to really disrupt Melbourne, Sydney, New York and many more low-lying coastal cities around the world,” Professor Nicholls said. “It’s the first metre or two that you have to worry about.”

The sea level has been rising at the rate of about 3 millimetres a year globally, and “there are worries that it will accelerate as warming increases”, Professor Nicholls said.

North America in an ice-free world.North America in an ice-free world. Photo: National Geographic

The World Meteorological Organisation overnight released its latest annual report, showing that the concentration of greenhouse gases that trap more of the sun’s heat in the earth’s biosphere are at record levels, with the increase accelerating.

National Geographic noted that the last time the earth was ice-free was 34 million years ago during the Eocene period, when alligators swam in Arctic swamps.

An ice-free world would see present-day London underwater, the Netherlands and Denmark lost. Bangladesh, home to 160 million people,would no longer exist and land now home to 600 million Chinese would be submerged. The US would have a lot fewer states, with the east coast including Florida lost to the sea, the National Geographic maps show.

Asia in an ice-free world.Asia in an ice-free world. Photo: National Geographic

The world’s ice caps, glaciers and permanent snow contain about 24 million cubic kilometres of water, according to the US Geological Survey. Antarctica and Greenland make up about 90 per cent of the total ice.

Read more: http://www.smh.com.au/environment/climate-change/what-the-world-would-look-like-if-all-the-ice-melts-20131107-2x2p9.html#ixzz2jxKQ4a1H