As the planet warms, it risks crossing catastrophic tipping points: thresholds where Earth systems, such as ice sheets and rain forests, change irreversibly over human lifetimes.
Scientists have long warned that if global temperatures warmed more than 1.5 degrees Celsius (2.7 Fahrenheit) compared with before the Industrial Revolution, and stayed high, they would increase the risk of passing multiple tipping points. For each of these elements, like the Amazon rain forest or the Greenland ice sheet, hotter temperatures lead to melting ice or drier forests that leave the system more vulnerable to further changes.
