At the recent COP28 United Nations climate talks, two men were key to clinching the agreement for the world to transition away from fossil fuels. United States special climate envoy John Kerry, 80, and his Chinese counterpart Xie Zhenhua, 74, helped bridge deep disagreements over references to fossil fuels in the final decision of the Dubai conference. Their close cooperation also helped create the landmark 2015 Paris climate agreement. The friendship and strong rapport between both men have been fundamental in maintaining progress in the often fraught world of climate diplomacy. China and the US are the world’s largest greenhouse gas polluters and what they decide, and how they cooperate, can shape the course of global climate action.

The two men have now retired, and they leave behind a powerful legacy but also much unfinished work that their replacements need to urgently continue. China has announced Mr Xie’s replacement – career diplomat Liu Zhenmin, 68, who has considerable experience in climate negotiations. A replacement for Mr Kerry has yet to be announced. Ahead of COP28, Mr Kerry and Mr Xie met at Sunnylands, a Californian retreat, to craft an agreement on US-China climate cooperation. They issued the Sunnylands statement on enhancing collaboration, agreeing to back an ambitious global renewable energy target and work together on plastic pollution, forest loss and cutting emissions of methane, a powerful greenhouse gas. The new climate envoys, once fully in place, must focus on achieving these goals. Fortunately, Mr Kerry and Mr Xie also agreed at Sunnylands to operationalise a US-China working group on enhancing climate action. That group held its first meeting on Jan 12, and it aims to sustain progress during the shift to the new climate envoys and turbulent US presidential election.