The journal Nature just published a paper, "Mass balance of the Antarctic Ice Sheet from 1992 to 2017," which documents accelerating ice loss in Antarctica over the last few decades. According to the study authors, Antarctica's ice loss has been driven by melting of the West Antarctic ice sheet while the East Antarctic ice sheet appears to have gained some mass in recent years. The paper received a lot of press in major news outlets. Sample headlines:
Antarctica shed 3 trillion tonnes of ice since 1992, and counting Axios
Antarctica Is Melting More Than Twice as Fast as in 2012 The New York Times
Antarctic ice loss has tripled in a decade. If that continues, we are in serious trouble. The Washington Post
Some context:
The West Antarctic ice sheet rests on ground below sea level, which makes it potentially unstable. It is possible that this could collapse rapidly and raise sea levels by 3.2 m, possibly within 500 years. Antarctic Glaciers.org
"We're still talking about roughly a half a millimeter per year," DeConto said. "That isn't going to sound horribly unmanageable. But remember for the northern hemisphere, for North America, the fact that the location in West Antarctica is where the action is amplifies that rate of sea level rise by up to an about additional 25 percent in a city like Boston or New York.” The Washington Post, quoting Rob DeConto, co-author of Antarctic Ice Sheet study.
Antarctica has the potential to contribute more than a metre of sea-level rise by 2100 and more than 15 metres by 2500, if emissions continue unabated. DeConto and Pollard (2016) "Contribution of Antarctica to past and future sea-level rise."
Bottom line: the melting of the West Antarctica ice sheet may contribute somewhere from a few inches to four feet* to rising sea levels by 2100 and 10.5 - 50 feet by 2500.
Note that the high end of the above estimates assumes no reduction in emissions, which would require a reversal of current trends. These trends include: dematerialization of production, sustainable intensification of agriculture, reforestation (allowing more land to revert to forest), dematerialization of consumption (“peak stuff”), spread of renewables, declining carbon intensity, ongoing energy efficiency improvements, growing market for electric cars, decoupling between economic growth and emissions, declining car ownership in cities, and slowing global population growth – to name a few.
Another paper on Antarctica appeared in Nature on the same date as the above study. It found that the East Antarctic Ice Sheet "did not retreat significantly over land during the warm Pliocene epoch, approximately 5.3 to 2.6 million years ago, when atmospheric carbon dioxide concentrations were similar to today's levels" (Shakun, Corbett, et al, 2018). This particular study got very little press.
Thus, according to both Nature papers, East Antarctic ice loss is not an issue at this time. West Antarctica is the problem. Odd then that the New York Times article, Antarctica Is Melting More Than Twice as Fast as in 2012, implies that the whole continent of Antarctica is in danger of melting, thereby greatly amplifying the threat to coastal populations and habitat:
Between 60 and 90 percent of the world’s fresh water is frozen in the ice sheets of Antarctica, a continent roughly the size of the United States and Mexico combined. If all that ice melted, it would be enough to raise the world’s sea levels by roughly 200 feet.
Such speculation does no service to the cause of combating climate change. It just provides skeptics and lukewarmers with more evidence the US media is full of scaremongers who exaggerate the threat of climate change and therefore are not to be trusted. Protecting coasts from sea encroachment calls for collective problem-solving, which is not served by alienating half the collective.
Next: How to protect coasts from rising sea levels
*Conversion: 1 millimeter (mm) = .039 inches and 1 meter (m) = 3.28 feet
References:
(2018). "Mass balance of the Antarctic Ice Sheet from 1992 to 2017." Nature 558(7709): 219-222. https://www.nature.com/articles/s41586-018-0179-y
DeConto, R. M. and D. Pollard (2016). "Contribution of Antarctica to past and future sea-level rise." Nature 531: 591. https://www.nature.com/articles/nature17145
Shakun, J. D., L. B. Corbett, et al. (2018). "Minimal East Antarctic Ice Sheet retreat onto land during the past eight million years." Nature 558(7709): 284-287. DOI: 10.1038/s41586-018-0155-6