A new study based on cutting-edge computer modeling, completed by climate scientists at the Victoria University Antarctic Research Centre in New Zealand, takes into account an important variable that has a very large impact on the potential rise of sea levels. The variable? Melting of the Antarctic ice shelves.
An excellent article on the Science Daily website summarizes the findings quite well:
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, according to new research published in Nature.
The research highlights the moral significance of decisions made now about mitigating climate change.
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.
Previous estimates from the Intergovernmental Panel on Climate Change (IPCC) in 2013 had predicted that the maximum sea level rise from a 2 degree rise in global average temperatures would be only 5 centimeters. However that IPCC estimate did not take into account certain things that happen when a warmer sea interacts with the ice shelves.
The article continues:
“Our new models include processes that take place when ice sheets come into contact with the ocean, he [Professor Tim Nash], 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.”
Significantly, the new study’s results are based on the most conservative models possible. Those involved in the study see it as a moral imperative, one that can affect future generations for thousands of years, for the current generations to address:
“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.
“Without significant reduction in greenhouse gas emissions over the next couple of decades, we will commit the Antarctic ice sheet to ongoing and widespread melting for the next few thousand years. Is that something for which we really want to be responsible?”
Will we, as a species considering the affects of our actions on our only home, make the necessary changes to avoid the potential global disaster? The book Don’t Even Think About It – Why Our Brains are Wired to Ignore Climate Change, by George Marshall suggests that we won’t, until it’s too late.
The only scenario that the New Zealand team studied which did not result in sea level rise was one where humans reduced carbon emissions, starting now. The alarm has been sounded, will the human race wake up and smell the coffee?
See the excellent article on the Science Daily website for more details.
Source: ScienceDaily.com – “Two degree Celsius warming locks in sea level rise for thousands of years“
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