For years, climate diplomats were told that one more "herculean effort" could keep global warming within 1.5C. This week, the head of the UN Environment Programme (Unep) admitted that the effort never came. "We procrastinated, and now we are saying this window has closed," said Inger Andersen, Unep's executive director, as her agency published its annual emissions gap report.

The numbers that follow are demanding. To keep warming near 1.7C, the world would have to cut emissions by 18% by 2030 and by 45% by 2035, compared with current policy paths. Even then, record heatwaves like those of recent months could become common rather than exceptional, although they would be less likely to grow drastically worse.

Global emissions in 2025 were broadly the same as in 2024, which looks like progress. Unep's analysts refused to call it a peak, however, because geopolitical turmoil and a continued reliance on fossil fuels, despite rapid growth in renewable energy, make any turning point uncertain. The report's central criticism is that governments have set long-term targets but have not turned them into short-term action. The politics are not helping.

The United States, the world's second-largest emitter after China, has withdrawn from the Paris agreement and is threatening to reverse its long decline in emissions. Bill Hare, chief executive of the Climate Analytics thinktank, argued that major fossil fuel producers such as the US and Saudi Arabia, which together supply a large share of the world's fossil fuels, must stop "playing politics".