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Two Degree Celsius Warming Locks In Sea Level Rise For Thousands of Years
The University of New South Wales (Australia) is reporting [unsw.edu.au] on research [nature.com] [abstract;full article paywalled] by an international team led by Dr Nicholas Golledge, a senior research fellow at New Zealand's Victoria University's Antarctic Research Centre. According to the article, a jump in global average temperatures of 1.5°C–2°C will see the collapse of Antarctic ice shelves and lead to hundreds and even thousands of years of sea level rise.
It goes on to say:
Using state-of-the-art computer modelling, Dr Golledge and his colleagues including researchers from UNSW simulated the ice-sheet’s response to a warming climate under a range of greenhouse gas emission scenarios. They found in all but one scenario (that of significantly reduced emissions beyond 2020) large parts of the Antarctic ice-sheet were lost, resulting in a substantial rise in global sea-level.
“The long reaction time of the Antarctic ice-sheet – which can take thousands of years to fully manifest its response to changes in environmental conditions – coupled with the fact that CO₂ lingers in the atmosphere for a very long time means that the warming we generate now will affect the ice sheet in ways that will be incredibly hard to undo,” Dr Golledge said.
...
“Around 93% of the heat from anthropogenic global warming has gone into the ocean, and these warming ocean waters are now coming into contact with the floating margins of the Antarctic ice sheet, known as ice shelves. If we lose these ice shelves, the Antarctic contribution to sea-level rise by 2100 will be nearer 40 centimetres.”
To avoid the loss of the Antarctic ice shelves, and a long-term commitment to many metres of sea-level rise, atmospheric warming needs to be kept below 2°C above present levels.
“Missing the 2°C target will result in an Antarctic contribution to sea-level rise that could be up to 10 metres higher than today,” Dr Golledge said.
“The stakes are obviously very high—10 percent of the world’s population lives within 10 metres of present sea level.”
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“The striking thing about these findings is that we have taken the most conservative estimates possible,” said co-author of the paper, Dr Chris Fogwill from UNSW Australia's Climate Change Research Centre.
“In all IPCC global warming scenarios, only one (RCP2.6) saw Antarctic ice shelves avoid ongoing collapse. In every other case we saw significant collapse and rising sea levels continue for hundreds to thousands of years.
“The results suggest Antarctic ice shelf stability has a tipping point dependent on a critical temperature threshold that can lead to substantial sea level rise even if we reduce emissions after that threshold has been reached.”
The findings raise an ethical decision for us all, according to Dr Golledge.
So, we have more research detailing the impact of AGW on sea levels. Interestingly, the paper's authors slam the IPCC's estimates of sea level rises due to Antarctic ice sheet melting as too modest.
