PLEA Network

New Scientist, 6 December 2023: Major climate tipping points could be triggered within a decade. The climate has warmed so much that we are already at risk of triggering five global “tipping points” that would have catastrophic effects worldwide and couldn’t be reversed easily if at all, according to a major report. As the world goes past 1.5°C of warming, it will be increasingly likely that we will cross these tipping points, and there will be a growing risk of this resulting in others as well. “Triggering one tipping point could trigger another in a kind of dangerous domino effect,” says Tim Lenton at the University of Exeter in the UK, the report’s lead author. “But also these tipping points in the Earth system could, in turn, trigger damaging tipping points in societies, things like food security crises, mass displacement and conflicts. Stopping these threats is possible, but it’s going to require urgent global action.” A tipping point is where a small alteration in a system can cause abrupt changes that are hard to reverse or are irreversible, because of amplifying feedback processes. Lenton says this is like leaning back on a chair: when it is near the balance point, just a small nudge can make the chair fall over. The report, put together by more than 200 researchers worldwide, brings together all the existing studies on tipping points and also includes research that is about to be published. According to the report, the five major tipping points we are near to crossing are: the loss of the Greenland ice sheet, the demise of the West Antarctic ice sheet, the die-off of tropical coral reefs, the abrupt thaw of large areas of Arctic permafrost and the slowing of an ocean current known as the North Atlantic subpolar gyre. The subpolar gyre is a circular current south of Greenland where salty water cools and sinks. It is linked to the Atlantic meridional overturning circulation (AMOC), but there is growing evidence that the current could slow or stop separately from and sooner than the AMOC, says David Armstrong McKay, also at the University of Exeter. Read more here