A peer-reviewed study in Nature has provided the most alarming assessment yet of climate system stability, concluding that three of Earth's sixteen major climate tipping points may already have been crossed.
The study identifies three that show signatures of having already been activated: the collapse of the West Antarctic Ice Sheet (eventually raising sea levels by 5.3 metres); the die-off of the Amazon rainforest's southeastern and central zones; and the thawing of boreal permafrost (releasing enormous quantities of stored carbon regardless of human action).
"Every fraction of a degree of warming we prevent matters," said the lead author. "We may have already activated some tipping points, but we are nowhere near all of them. The difference between 1.5 and 2 degrees could determine whether we cross five tipping points or thirteen."
This is not a reason to give up. It is a reason to act with greater urgency than ever. The worst is not inevitable โ but only if we act now. โ Lead author, Cambridge University