Farewell, Kerry and Xie: US and China climate envoys leave stage their friendship helped define

As the final fraught hours of the Cop28 UN climate summit last A approached December, a private gathering in a quiet corner marked a joyful milestone.

- Fiona Harvey

John Kerry, the US presidential envoy for climate, celebrated his 80th birthday, and the guest of honour was his 74-year-old Chinese counterpart, Xie Zhenhua.

It was a warm and familial occasion: even Xie's eight-year-old grandson was present. "Why are you still working so hard, at your age?" he asked of Xie and his "good old friend" Kerry. "Because we are all passionate about this common cause of addressing climate change," was Xie's answer, recounted at an unusual US-China press conference after the summit.

For both men, who have been pivotal to climate negotiations since before the signing of the landmark 2015 Paris agreement, that hard work is now over. First Xie and then, last week, Kerry announced his retirement, leaving a global climate stage that their close personal relationship has helped to define. Despite rising tensions between their countries, they forged US-China collaboration on climate action that has been essential to reshaping the global economy - but also a frustrating barrier to climate progress.