Joe Biden and Xi Jinping, leaders of two biggest carbon emitters, among those not attending summit in New York.

The climate ambition summit, convened by António Guterres, the UN’s secretary general, will feature more than 100 national governments who have traveled to New York to outline renewed plans to curb global heating and help people adapt to its impacts. The UN has said the event will “showcase first movers and doers” among countries most willing to act on the climate crisis.

But the summit has failed to attract the leaders of the two biggest carbon emitters, with neither Joe Biden, the US president, nor Xi Jinping, president of China, attending. Rishi Sunak, the British prime minister, and Emmanuel Macron, the French president, are also missing the gathering.