- West Antarctica ice loss is now unstoppable, regardless of human CO2 emissions.
- Expect 1-2m of sea level rise by 2100.
- Expect 3-5m of sea level rise by 2200.
- East Antarctica ice is also destabilizing, if this continues expect an additional 5m by 2200, and 10+m later.
I observe that sea level rise predictions worsen with each new major study. I therefore interpret these predictions as best case.
We have known about this threat for 50 years. More evidence in support of Varki’s denial theory.
Recent studies, surveyed in this report, suggest that WAIS passed a tipping point for large-scale deglaciation decades ago.
This should not be surprising, because such an event was foreseen almost 50 years ago. In 1968, pioneer glacier researcher John Mercer predicted that the collapse of ice shelves along the Antarctic Peninsula could herald the loss of the ice sheet. Ten years later, Mercer contended that “a major disaster — a rapid deglaciation of West Antarctica — may be in progress … within about 50 years” (“West Antarctic ice sheet and CO2 greenhouse effect: a threat of disaster”, Nature 271:321-325).
He said that warming “above a critical level would remove all ice shelves, and consequently all ice grounded below sea level, resulting in the deglaciation of most of West Antarctica”. Such disintegration, once under way, would “probably be rapid, perhaps catastrophically so”, with most of the ice sheet lost in a century. Credited with coining the phrase “the greenhouse effect” in the early 1960s, Mercer’s Antarctic prognosis was widely ignored and disparaged at the time. Now in seems uncannily prescient.
The author warns that reality may worsen as scientific understanding improves.
The general view amongst scientists I have communicated with is to expect a sea-level rise this century of at least 1 metre, and perhaps in excess of 2 metres in light of the work surveyed above. Scientists have found the business of putting a true upper limit on how much ice could melt — and how quickly — is a difficult one.
Amongst a myriad of devastating global impacts, a 1-metre sea-level rise would inundate up to 20% of the land area of Bangladesh and displace 30 million people, wipe out 40-50% of the Mekong Delta, flood one-fourth of the Nile Delta, and depopulate some coral atoll small states.
Meanwhile, the majority of citizens around the world deny this issue exists and do not discuss, let alone act, on possible changes to their lifestyles.
And Obama sets an example by taking his second long distance vacation in as many months.