The leaders of most of the world's biggest greenhouse gas emitters will gather in Scotland on Sunday, aiming to thrash out plans and funds to tilt the planet towards clean energy. But the man running the biggest of them all likely won't be there.

Chinese President Xi Jinping's expected absence from the talks could indicate that the world's biggest carbon dioxide producer has already decided that it has no more concessions to offer at the U.N. COP26 climate summit in Glasgow after three major pledges since last year, climate watchers said.

Instead, China will likely be represented by vice-environment minister Zhao Yingmin along with veteran Xie Zhenhua, who was reappointed as the country's top climate envoy earlier this year following a three-year hiatus.