" it projects to, at 410 ppm, we have at least +30m of sea level rise already "baked into the pie"
Greenland and Antarctica hold about 66m of SLR.
Team Deciphers Sea-Level Rise From Last Time Earth’s CO2 Was as High as Today
BY EARTH INSTITUTE|AUGUST 30, 2019
Scientists have discovered evidence in a coastal cave off Spain showing that more than 3 million years ago, when temperatures were roughly equivalent to those projected for the end of this century, sea levels were as much as 16 meters higher than they are now.
blogs.ei.columbia.edu
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It's not an overnight process. Oceans won't be 16m higher by the end of the century. (If only) We could hold temperatures here, it would still take hundreds, if not thousand of years for the accumulated heat to erode the ice. However, if I'm reading this correctly, the equilibrium sensitivity may be about 5 degrees C, instead of 3-3.5, which would raise temperatures even more.
The results from climate models that are being run for CMIP6 have been talked about for a few months as the papers describing them have made it in to the literature, and the first assessments of the multi-model ensemble have been done. For those of you not familiar with the CMIP process, it is a periodic exercise for any climate model groups who want to have their results compared with other models and observations in a consistent manner. CMIP6 is the 5th iteration of this exercise (we skipped CMIP4 for reasons that remain a little obscure) that has been going since the 1990s.
The main focus has been on the climate sensitivity of these models – not necessarily because it’s the most important diagnostic, but it is an easily calculated short-hand to encapsulate the total feedbacks that occur as you increase CO2.
The first public hint of something strange going on, was at the Barcelona CMIP6 meeting in March earlier this year where this graphic showing Equilibrium Climate Sensitivity (ECS) for the models was prepared:
This showed that quite a few of the models were possibly coming in with sensitivities above 5ºC (grey bars were self-reported, green bars were calculated coherently from the archive). At about the same time, developers at the Hadley Centre and IPSL, wrote about their preliminary results. This was news because the previous IPCC report (and most assessments) have found the likely range of climate sensitivity is roughly 2 to 4.5ºC. For contrast the range in CMIP5 models was 2.1 to 4.6ºC.
realclimate.org |
