AS UN climate talks in Marrakesh enter their final few days, leaders have a lot on their minds. Political support for a green agenda will wane in America next year. Barack Obama has led international environmental-protection efforts; Donald Trump plans to oppose them. The switch comes just as a new report from the World Meteorological Organisation, a UN body, confirms that this year is virtually certain to be the hottest ever recorded—stealing the title from 2015. This will mean that 16 of the 17 most sweltering years ever tracked have occurred since the millennium.

Global temperatures this year are about 1.2 degrees Celsius above pre-industrial ones—dangerously close to the warming limit of 1.5C that politicians hope to achieve, as agreed during last year’s round of talks in Paris. Particular hot spots include Arctic regions, which are heating up at twice the rate of the rest of the world. While a single degree’s shift in temperature may have noticeable effects at the equator, in the Arctic it changes ice to water, totally altering the landscape. Once more sea-ice levels in the region remained worryingly low this year.

In the early part of 2016 the climate phenomenon El Niño, which affects sea temperature in the tropical Pacific and thus rainfall patterns around the world, explained much of the global heat. Some scientists believe the event may also mean that the world’s plants have become a less potent carbon sink than in recent years. This is another unwelcome switch. Rising concentrations of greenhouse gases in the atmosphere are warming the world apace. As of this year, levels of carbon dioxide are unlikely to dip below 400 parts per million until technologies to suck the stuff out of the atmosphere are deployed at scale. Millions of years have passed since the last time the concentration was this high.

Amid the troubling data, news that global emissions may be at or near their peak is welcome. Carbon-dioxide emissions from burning fossil fuels appear to be stabilising. Now they need to fall. Slowing demand for fossil fuels, and not just the growth in demand for them, is of utmost importance.