A climate change report calls for urgent action

THREE years ago the world agreed in Paris to keep global warming below 2C relative to pre-industrial levels, and preferably no higher than 1.5C. Scientists expecting a fuzzier climate-friendly commitment were astonished by the inclusion of the lower target, inserted at the insistence of low-lying island nations for which an additional half a degree could spell doom because of rising sea-levels. Since then researchers have explored the difference between the two scenarios in other areas, from biodiversity to frequency of natural disasters, as well as what it would take to achieve them. On October 8th the UN-backed Intergovernmental Panel on Climate Change published a survey of that literature. The much-anticipated report concludes that letting Earth warm beyond 1.5C presents a serious danger to humans and other species. It also presents four different possible routes to achieving this more ambitious aim (see chart), three of which require removing considerable amounts of carbon from the atmosphere using technology like Bioenergy with Carbon Capture and Storage (BECCS)burning crops and storing the resulting emissions deep underground (see our briefing on carbon capture). Governments, whose present Paris pledges put the planet on course for 3C of warming, had better read it carefully.