If you crave for a pint of beer at the end of a hard day, brace yourself: climate change is poised to make your favourite drink more scarce and pricey. Heatwaves and droughts will periodically cause sharp declines in barley yields, a crucial ingredient in most beer, according to a study. “Decreases in the global supply of barley lead to proportionally larger decreases in barley used to make beer,” said lead author Dabo Guan. Only the highest quality grain — less than 20% — is used to make beer, with most of the rest used as feedstock. “High-quality barley is even more sensitive to extreme weather events linked to climate change,” Mr. Guan said. During severe climate events, global beer consumption would decline by 16%, or nearly 30 billion litres — equal to all the beer quaffed each year in the U.S., Mr. Guan and a team of researchers reported in the journal Nature Plants . Beer prices in the wake of these disruptive weather events would, on average, double. By volume, beer is by far the most popular alcoholic drink in the world, with nearly 200 billion litres produced in 2017. Some countries will get hit harder by beer shortages and higher bar tabs than others, the study found. In China — whose 1.3 billion people collectively down more brew than any other nation — consumption would fall by a staggering 4.3 billion litres in a bad year. Britain would also get thirsty during a severe barley crunch, with consumption dropping by up to 1.3 billion litres, and the price of a pint doubling. Per capita, most of the top-20 beer-drinking nations are in Europe, along with the U.S., New Zealand and Australia. Barley as a source of food Mr. Guan and colleagues calculated the impact of severe weather events on yields in the world’s 34 most important barley-growing regions. An extreme weather year was defined as one with both heatwaves and drought more severe than once-a-century events before global warming began. From 2010 to the end of the century, they found, there will be 17 such events if global warming is capped under two degrees Celsius, and 139 if current rates of carbon pollution persist. In a climate-addled world where staple crops are predicted to decline in yield and nutritional value, pressure will likely mount to use barley as a source of food rather than to make brew.