Right now, we’re headed towards an ice-free planet. That takes us through the Eemian interglacial period of about 130,000 years ago when sea levels were 15 to 20 feet higher, when temperatures had been thought to be about 1°C warmer than today. Then we go back to the “early Pliocene, when sea level was about 25 m [82 feet] higher than today,” as NASA’s James Hansen and Makiko Sato explain in a new draft paper, “Paleoclimate Implications for Human-Made Climate Change.”
Hansen and Sato say we’re at or very near the highest temperatures of the current Holocene interglacial… With further global warming of the order of 3-6°C, they assert, “multi-meter sea level rise on the century time scale are not only possible, but almost dead certain
This blog has relayed such warning before. This most recent warning from Hansen & Sato re-emphasize the non-linearity of tipping points.
We suggest that a nonlinear process spurred by an increasing forcing and amplifying feedbacks is better characterized by the doubling time for the rate of mass disintegration, rather than a linear rate of mass change. If the doubling time is as short as a decade, multi-meter sea level rise could occur this century. Observations of mass loss from Greenland and Antarctica are too brief for significant conclusions, but they are not inconsistent with a doubling time of a decade or less.
Other Climate Progress posts on the topic of sea level rise
- Sea levels may rise 3 times faster than IPCC estimated, could hit 6 feet by 2100
- Satellite data stunner: “Our data suggest that EAST Antarctica is losing mass…. Antarctica may soon be contributing significantly more to global sea-level rise.”
- Nature: “Dynamic thinning of Greenland and Antarctic ice-sheet ocean margins is more sensitive, pervasive, enduring and important than previously realized.”
- New study of Greenland under “more realistic forcings” concludes “collapse of the ice-sheet was found to occur between 400 and 560 ppm” of CO2
- Climate researcher: “It is my assessment that we have had the strongest melting since they started measuring the temperature in Greenland in 1873.”
- Science: CO2 levels haven’t been this high for 15 million years, when it was 5° to 10°F warmer and seas were 75 to 120 feet higher — “We have shown that this dramatic rise in sea level is associated with an increase in CO2 levels of about 100 ppm.”
- Coastal studies experts: “For coastal management purposes, a [sea level] rise of 7 feet (2 meters) should be utilized for planning major infrastructure”