This week, the United Nations’ Intergovernmental Panel on Climate Change released a report confirming what a summer of wildfires, floods, and record temperatures had suggested: the planet is warming fast, and human are unquestionably responsible. However, the window to take action to fight climate change is not yet closed. Elizabeth Kolbert joins Evan Osnos, filling in for Dorothy Wickenden, to discuss the I.P.C.C. report; the politics of climate change; and her recent reporting from the Utah-Arizona border, where climate change has had a surprising effect on a national landmark.