Some of the most alarming science surrounding climate change is the discovery that it may not happen incrementally — as a steadily rising line on a graph — but in a series of lurches as various “tipping points” are passed. And now comes a new concern: These tipping points can form a cascade, with each one triggering others, creating an irreversible shift to a hotter world. A new study suggests that changes to ocean circulation could be the driver of such a cascade.
A group of researchers, led by Tim Lenton at Exeter University, England, first warned in a landmark paper 11 years ago about the risk of climate tipping points. Back then, they thought the dangers would only arise when global warming exceeded 5 degrees Celsius (9 degrees Fahrenheit) above pre-industrial levels. But last week, Lenton and six co-authors argued in the journal Nature that the risks are now much more likely and much more imminent. Some tipping points, they said, may already have been breached at the current 1 degree C of warming.