NEW YORK - The world’s top diplomat, António Guterres, the United Nations secretary-general, has lately been unusually blunt in his broadsides against fossil fuel producers. He has accused them of “profiting from destruction.” He has urged governments to stop funding coal and to put the brakes on new oil and gas projects. “History is coming for the planet-wreckers,” he has said.

But who are these “planet wreckers?” He doesn’t name them.

Not China, the world’s coal behemoth. Not Britain or the United States, who both have ambitious climate laws but continue to issue new oil and gas permits. Not the United Arab Emirates, a petrostate where a state-owned oil company executive is hosting the upcoming UN climate negotiations – a move that activists have decried as undermining the very legitimacy of the talks.

The contradictions show not only the constraints on Mr Guterres, a 74-year-old politician from Portugal who has made climate change his centrepiece issue, but also the shortcomings of the diplomatic playbook on a problem as urgent as global warming.

“The rules of multilateral diplomacy and multilateral summitry are not fit for the speedy and effective response that we need,” said Mr Richard Gowan, who decodes the rituals of the United Nations for the International Crisis Group.

The 2015 Paris climate accord asks only that countries set voluntary targets to address climate pollution. The agreements that come out of annual climate negotiations routinely get watered down, because every country, including champions of coal, oil and gas, must agree on every word and comma.

The secretary-general can cajole but not command, urge but not enforce. He doesn’t name specific countries, though nothing in the United Nations Charter prevents him from doing so.

Despite his exhortations, governments have only increased their fossil fuel subsidies, to a record US$7 trillion (S$9.5 trillion) in 2022. Few nations have concrete plans to move their economies away from fossil fuels, and many depend directly or indirectly on revenues from coal, oil and gas. The human toll of climate change continues to mount.

“He has interpreted his role as a sort of truth teller,” said Professor Rachel Kyte at the Fletcher School at Tufts University, who is a former UN climate diplomat. “The powers available to h...