At 2C Increase, We Can Expect 20 Meters Of Sea Level Rise From Antarctica
We know that our planet has experienced warmer periods in the past, during the Pliocene geological epoch around three million years ago. Our research, published today, shows that up to one third of Antarctica’s ice sheet melted during this period, causing sea levels to rise by as much as 20 metres above present levels in coming centuries. [See also the press release, New research on past sea levels reveals potential for widespread melting of Antarctica. –Des]
We were able to measure past changes in sea level by drilling cores at a site in New Zealand, known as the Whanganui Basin, which contains shallow marine sediments of arguably the highest resolution in the world. Using a new method we developed to predict the water level from the size of sand particle moved by waves, we constructed a record of global sea-level change with significantly more precision than previously possible.
The Pliocene was the last time atmospheric carbon dioxide concentrations were above 400 parts per million and Earth’s temperature was 2°C warmer than pre-industrial times. We show that warming of more than 2°C could set off widespread melting in Antarctica once again and our planet could be hurtling back to the future, towards a climate that existed three million years ago.
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Our study also shows that most of the sea-level rise during the Pliocene came from Antarctica’s ice sheets. During the warm Pliocene, the geography of Earth’s continents and oceans and the size of polar ice sheets were similar to today, with only a small ice sheet on Greenland during the warmest period. The melting of the Greenland ice sheet would have contributed at most five metres to the maximum 25 metres of global sea-level rise recorded at Whanganui Basin. Of critical concern is that over 90% of the heat from global warming to date has gone into the ocean. Much of it has gone into the Southern Ocean, which bathes the margins of Antarctica’s ice sheet
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https://desdemonadespair.net/2019/10/if-warming-exceeds-2c-antarcticas-melting-ice-sheets-could-raise-seas-20-meters-in-coming-centuries.html
