Nearly 50 million may face acute hunger from El Niño, UN estimates
El Niño occurs every few years and typically lasts about a year. In normal years, warm water collects in the western Pacific. During El Niño, that mass of warm water shifts east toward South America, moving the tropical rains it generates along with it. The eastward shift of warmer water is one of the harbingers scientists measure to predict the strength of each event.
This summer’s temperatures in the east-central Pacific rank among the highest on record, according to data from the National Oceanic and Atmospheric Administration. Projections show the current event potentially exceeding previously powerful El Niños.
The number of named storms in the northeastern Pacific is about 40 percent above average for this time of year, according to data from Colorado State University. Hawaii has seen unusually strong cyclone activity this summer, with Hurricanes Lala and Lowell bringing destructive winds and flooding. More than a half-million acres have burned in Indonesia this year, forcing school closures and harming air quality as far away as Singapore and the Philippines. Previous strong El Niños in 1997 and 2015 also fueled devastating blazes in Indonesia.
As ocean evaporation shifts east during El Niño, it generates warm air that rises into the atmosphere and migrates north and east, speeding up as it travels. Those high-pressure winds feed into the subtropical jet stream, giving it an extra boost that propels the stream further east over North America and causes it to blow stronger and steadier. The reinforced jet stream delivers more rain and storms to the southern United States, with precipitation peaks in winter potentially bringing flooding and coastal erosion to California and severe thunderstorms to Gulf states.
While El Niño promotes cyclones in the Pacific, it tends to stifle them in the North Atlantic. In El Niño years, warm air rising off the Pacific generates high-altitude winds that blow east toward the tropical Atlantic, according to Phil Klotzbach, a hurricane forecaster at Colorado State University. “This results in increased levels of Atlantic vertical wind shear,” Klotzbach said. “Too much vertical wind shear tears apart hurricanes.” The North Atlantic typically gets more than three hurricanes by this time of year; so far there have been none.
El Niño’s effects extend to food security in regions distant from the Pacific. “Southern Africa has a pretty strong tendency for drought during El Niño,” said Emily Becker, an atmospheric scientist at the University of Miami. “These can have very significant impacts because of food insecurity.” The U.N. World Food Program recently estimated that El Niño could push almost 50 million more people into acute hunger by next year, with southern Africa and Central America particularly at risk.
El Niño offers one redeeming aspect compared with other natural disasters, according to Becker. “Disasters happen all the time,” Becker said. “And in El Niño years, we actually know where they will happen. We can prepare.”