Antarctic ice sheet melt could cause 60m sea level rise


If the global temperature keeps rising, as it's on track to do at an alarming rate, the resulting loss of an Antarctic ice sheet could cause a devastating rise in the sea level, a new study warns.

The East Antarctic ice sheet was previously thought to be stable in comparison to its volatile cousin, the West Antarctic. But new research, led by the University of Urbino's Professor Simone Galeotti, suggests by the end of the century, carbon dioxide levels could rise high enough to cause the eastern ice sheet to melt.

Sixteen years ago a drilling project was carried out at the Antarctic's Ross Sea, near New Zealand's Scott Base, taking samples of layers of sediment over 1500m. It gave the scientists a picture of what the ice looked like millions of years ago as it grew and shrank through natural warming and cooling cycles.

Paleo-climatologist and lead author Professor Tim Naish says the cores show the eastern ice sheet was initially quite dynamic. It was only after carbon dioxide levels dropped that it stabilised into the sheet we know today.

"It advanced and retreated many times between 34 to 35 million years ago, before finally stabilising at its largest extent when atmospheric carbon dioxide levels dropped below a threshold of 600 parts per million," he says.

Currently, carbon dioxide levels are at 400 parts per million, and that's expected to rise.

"If the Antarctic ice sheet completely melted, global sea level would rise about 60 metres. It's a sleeping giant."

Prof Naish had previously co-authored a paper which modelled how Antarctica would respond to a range of warming scenarios.

Antarctica's ice shelves hold the larger ice sheets in place, preventing the sheets -- which make up the body of the continent -- from sliding into the ocean and melting.

There was a dramatic loss of the ice shelves in all but one of the simulations. In that modelling, it was predicted the loss of the Antarctic ice shelves would cause sea levels to rise up to 10m by 2100.

And the new research comes on the heel of new modelling by Australian researchers which suggests the global temperature could rise even faster than earlier predicted, now predicted to rise by 1.4degC as early as 2020.

In November last year, nearly 200 countries came together to sign a pact intended to restrict global warming to a maximum of 2degC, with a goal of 1.5degC. At the meeting, New Zealand agreed to limit its own emissions to 30 percent below 2005 levels.

But the pact was criticised as not doing enough -- only predicted to limit warming to around 2.7degC -- and the Australian research hammers that point in.

In the new model it looks at energy use per person, as well as a growing population and economy, to predict how much energy will be needed to fuel the world. From there, it predicts the rise in emissions.

Professor Ben Hankamer from the University of Queensland has called for a greater push to solar power to help slow the emission growth, while still providing energy for a growing population.

In only two hours, he says, Earth's surface receives enough solar energy to power the global economy for a year.

"A cost-neutral strategy that governments should consider to fast-track this transition is diverting the $500 billion used to subsidise the fossil fuel industry internationally, to assist the global renewable sector."