James Hansen warns of climate ‘tipping points,’ urges moratorium on new coal plants without carbon capture

Dr. James Hansen, a climate scientist who discussed his decades of work at the Goddard Institute, told an audience in Missoula that “there’s more global warming already in the pipeline” because of the ocean’s slow response and that positive feedbacks now predominate in the climate system.

Hansen said those feedbacks and the warming still to come create a risk of passing “tipping points in the climate system” that could produce changes ‘‘out of your control’’ and lead to a substantially different planet. He described observed changes including a doubling of glacier discharge rates in recent decades and a global sea-level rise of about 3.5 centimeters per decade, and warned that if current trends continued “we will be at such a level that it’s just impractical” to meet safer stabilization scenarios.

Why it matters: Hansen framed the talk around long-term paleoclimate evidence and recent observations to argue that human-caused greenhouse-gas forcings now dwarf natural forcings, and that policy choices in the coming years will determine whether irreversible outcomes — large…