Dealing with climate change: Seven ways the planet could tip into 'Hothouse Earth'

Even if humanity slashes greenhouse gas emissions in line with Paris climate treaty goals, the planet could overwhelm such efforts and irretrievably tip into a hellish ‘hothouse’ state, top scientists warned on Monday. “The Earth System may be approaching a planetary threshold that could lock in a continuing, rapid pathway towards much hotter conditions — Hothouse Earth.” Weakened carbon ‘sinks’ Earth’s forests and oceans have together absorbed more than half of carbon pollution over the last several decades, even as those emissions grew. Forest ‘dieback’ Global warming of 3 C could condemn 40 percent of the Amazon forests to dieback, a process that would reach well into the next century, according to recent research. Ice sheets, sea level Experts disagree on how much global warming it will take to condemn the West Antarctic and Greenland ice sheets and how quickly they would melt, but all agree that such a tipping point exists, with estimates ranging from 1 C to 3 C. The consequences for humankind would be catastrophic: Two-thirds of the world’s megacities are less than 10 metres about sea level, and is much of the agricultural land that feeds them. “The risk of tipping cascades could be significant at a 2 C temperature rise, and could increase sharply beyond that point.” “This cascade of events may tip the entire Earth system into a new mode of operation,” said co-author Hans Joachim Schellnhuber, Director of the Potsdam Institute for Climate Impact Research.