If Earth heats up beyond 1.5 degrees, the impacts don't get just slightly worse--scientists warn that abrupt changes could be set off, with devastating impacts around the world. As the 27th annual climate negotiations are underway in Egypt and the world is set to blow past that 1.5°C warming threshold, Emily Kwong talks to climate correspondents Rebecca Hersher and Lauren Sommer about three climate tipping points--points of no return that could cause big changes to the Earth's ecosystems. Email the show at shortwave@npr.org.