Amounts of warming previously thought to be safe may instead trigger widespread melting of the world’s ice sheets and other catastrophic impacts, scientists said….
“There’s evidence that climate sensitivity may be quite a bit higher than what the models are suggesting,” said Ken Caldeira, a senior scientist at Stanford University’s Carnegie Institution for Science.
That’s from a Daily Climate piece on this panel discussion at last weeks AGU meeting:
The sensitivity issue is a complicated one, as I’ve discussed. The AGU discussion certainly helps clarify key issues and suggests that some effort is being put into a reconciliation of the different ways of calculating.
Don’t miss the back and forth on whether we are headed toward 25 meters of sea level rise or 70 meters at the end. For some of the science, see 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”.
If you’re interested on Caldeira’s work on a very high sensitivity – 5.5°C to 8°C (10 to 14 F) — click here. It is based on the PETM 55 million years ago and “having strong functioning methane feedbacks.” Thankfully we’ve got nothing to worry about in the Anthropocene (see”NSIDC : Thawing permafrost feedback will turn Arctic from carbon sink to source in the 2020s, releasing 100 billion tons of carbon by 2100).
Here’s more of the Daily Climate piece: