A prestigious, wise group of climate scientists just scared the shit out of me. “Climate tipping points – Too risk to bet against” came out in Nature on November 27. Tipping points, “large-scale discontinuities,” were traditionally shoved off into the future, the future of +5C, but over the last couple of years, scientists have begun to see evidence of them as possibilities over +1C or +2C. The West and East Antarctic ice sheets are perilously close to going into irreversible melting and the Greenland ice sheet could be “doomed” at +1.5C. At +2C, the Arctic has a 10-35% chance of going ice-free in summer. 99% of coral reefs could die at +2C, triggering onward effects. The Amazon might tip into irreversible drying out sooner than expected. Throw in forest fires, permafrost thawing, and a slowdown in Atlantic circulation, and these sages see nine tipping points flaring in complex, reinforcing combinations. Their conclusion?:
Some scientists counter that the possibility of global tipping remains highly speculative. It is our position that, given its huge impact and irreversible nature, any serious risk assessment must consider the evidence, however limited our understanding might still be. To err on the side of danger is not a responsible option. If damaging tipping cascades can occur and a global tipping point cannot be ruled out, then this is an existential threat to civilization. … In our view, the evidence from tipping points alone suggests that we are in a state of planetary emergency: both the risk and urgency of the situation are acute.