As global warming passes certain limits, dire changes will probably become irreversible, the researchers said, including the loss of polar ice sheets and the death of coral reefs. A summer sunset over Disko Bay in Ilulissat, Greenland. Credit…Mario Tama/Getty Images Failure to limit global warming to the targets set by international accords will most likely set off several climate “tipping points,” a team of scientists said on Thursday, with irreversible effects including the collapse of the Greenland and West Antarctic ice sheets, abrupt thawing of Arctic permafrost and the death of coral reefs. The researchers said that even at the current level of warming, about 1.1 degrees Celsius (2 degrees Fahrenheit) above preindustrial levels, some of these self-sustaining changes might have already begun. But if warming reached above 1.5 degrees Celsius, the more ambitious of two targets set by the 2015 Paris Agreement, the changes would become much more […]