Droughts hurt world’s largest economies

Severe droughts across the Northern Hemisphere—stretching from the farms of California to waterways in Europe and China—are further snarling supply chains and driving up the prices of food and energy, adding pressure to a global trade system already under stress.

Parts of China are experiencing their longest sustained heat wave since record-keeping began in 1961, according to China’s National Climate Center, leading to manufacturing shutdowns owing to lack of hydropower. The drought affecting Spain, Portugal, France and Italy is on track to be the worst in 500 years, according to Andrea Toreti, a climate scientist at the European Commission’s Joint Research Center.

In the American West, a drought that began two decades ago now appears to be the worst in 1,200 years, according to a study led by the University of California, Los Angeles.

Researchers compare droughts by measuring the growth of annual tree rings that reflect rainfall and temperature from year to year in specific areas. Climate scientists say this year’s dry spells are partly because of La Niña, a cyclical pattern of cooler water in the eastern Pacific Ocean that pushes the atmospheric jet stream northward, leaving parts of Europe, the U.S. and Asia with less rain. The United Nations says the number of droughts worldwide has risen 29% since 2000 because of land degradation and climate change.