MATHEMATICAL MODELS of climate change predict that the severity of natural disasters will increase as the world warms. The cyclone that hit Mozambique on March 14th, killing perhaps 1,000 people, has further focused attention on the risks posed by rising temperatures. Even so, the man-made carbon emissions that drive global warming continue to grow. According to a new report from the International Energy Agency (IEA), a think-tank based in Paris, energy-related CO2 emissions rose by 1.7% last year, to 33.1 gigatonnes. The increase, of 560 metric tonnes compared with 2017, was equivalent to a full year’s worth of emissions from international aviation.

Carbon emissions have been driven higher by increasing demand for all types of energy. Broadly speaking, changes in energy demand track the fortunes of the world economy. Robust global GDP growth of 3.7% last year caused energy demand to rise by some 2.3%, its fastest pace for a decade. And although energy efficiency did improve and use of renewable sources did increase—solar power generation rose by 31%—these gains were dwarfed by the growth in the use of fossil fuels, which accounted for 70% of the rise in global energy consumption.

Burning of coal, the most egregious source of carbon, accounted for a third of the growth in emissions. A new generation of coal-fired power plants in Asia was responsible for nearly all the additional global demand. Those power plants are expected to remain active for another 40 years. Much more encouragingly, and despite President Donald Trump’s advocacy for America’s coal industry, America’s abundant supply of natural gas has led firms rapidly to switch from coal to gas power. Natural-gas consumption in the United States increased by 10% last year, equivalent to Britain’s total annual consumption.

Perhaps the most worrying finding in the report is the threat of a feedback loop between severe weather events and carbon emissions. According to the IEA, a hotter-than-average summer and colder-than-average winter led to greater use of heating and air conditioning, which together were responsible for about half of the rise in energy demand in America and roughly a fifth of the worldwide increase. If humans keep burning fuel to shield themselves from extreme temperatures, and the emissions produced by that activity cause temperatures to become ever more extreme, the worst-case scenarios for climate change are more likely to materialise.