RESEARCH by Robert Jackson, from Stanford University in California, and Corinne Le Quéré of the University of East Anglia, in Britain, and others from the Global Carbon Project, an analysis group, just published in Nature Climate Change, estimates that the growth of carbon-dioxide emissions around the world will stall in 2015. The main reason the academics have for thinking so is China’s economic slowdown. The drop in that country’s coal consumption means that in 2014 its emissions of the gas grew by only 1.2%—in contrast to an average annual growth rate over the ten previous years of 6.7%. Total CO2 emissions from fossil fuels and industry around the world grew just 0.6% in 2014. That was down from an average of 2.4% in the prior decade. Delegates to the current UN climate negotiations in Paris may tout this as evidence that economic growth can be uncoupled from increasing emissions, for gross world product last year increased by 2.5%.

China remains the world’s biggest emitter of CO2. By the authors' estimates, the activities of its people released 9.7 billion tonnes of the stuff—27% of the world’s total—into the air last year. (America was second, unleashing 5.6 billion tonnes.) At the same time, though, more than half of its new energy needs were met using low-carbon sources, including wind, sunlight and nuclear power. Indeed, China invests more in renewable-energy production than America and Japan combined.

According to its pledge for the Paris talks, China aims to ensure its emissions peak by 2030, and decline thereafter. Debate rages over how much the country actually pollutes, however. One study, published in Nature this year, found that Chinese carbon emissions were 14% lower in 2013 than previously estimated. Other research suggested that between 2011 and 2013 they were up to 11% higher. The new report claims to take such discrepancies into account.

Given China’s importance to efforts to reduce the world’s emissions of greenhouse gases, the discrepancies remain worrying. They may, for example, doom its national carbon-trading scheme, which is scheduled for launch in 2017. Moreover, voracious coal-burning may accelerate elsewhere. Poor countries that wish to emulate China’s economic growth are likely to take a similar track. More than 1.2 billion people still lack electricity. Coal remains a cheap way to generate it. Population growth over the coming decades will drive demand further. The UN reckons about 9.7 billion people will be living, breathing, driving and cooking on the planet by 2050—up from 7.3 billion now.

The damage already done to the environment should not be overlooked, either. In 2015 the concentration of CO2 in the atmosphere reached 400 parts per million—higher than at any previous point in the past 800,000 years. And this year is likely to be the warmest on record. (The strong Niño climatic event under way is a factor.) It is welcome news that growth in emissions has slowed, and looks set to cease, albeit probably temporarily. But concentrations of CO2 will continue to rise, even if any flatlining is permanent. Emissions must therefore actually decline if the risks of further climate change are to be avoided.