How the US is set to return to the fight against global warming. Justin Rowlatt speaks to Todd Stern, the US special envoy for climate change under Barack Obama, and to Rache Kyte, dean of the Fletcher School at Tufts University in the US, about plans to reverse the environmental policies of the Trump era. Christiana Figueres, who negotiated the Paris Agreement on climate change for the UN, tells us why she's excited by the return of the US to the global stage.

(Photo: Wind turbines near Palm Springs, California, Credit: Getty Images)