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The long-term rainfall history in CHIRPS has enabled CHC researchers to refine their understanding of the La Niña teleconnection. By comparing global weather records and the predictions of climate models to the CHIRPS records, they have discovered the importance of the “western V,” an arc of hot Pacific water that can appear during a La Niña event. Shaped like a less-than sign, it angles from Indonesia northeast toward Hawaii and southeast toward the Pitcairn Islands, and it forms as La Niña pens warm waters in the western Pacific.
It has far-reaching consequences. As water temperatures spike, energetic evaporation saturates low-level winds flowing west from the cool eastern Pacific. The moist winds dump their water over Indonesia—the wet get wetter. The winds, now high and dry, continue their march west across the Indian Ocean and drop down over East Africa, preventing the intrusion of nearby moist ocean air and breaking up rain clouds. Global warming is strengthening these effects, causing them to linger even after a La Niña fades. And it appears that because of the ongoing ocean warming, they can happen without a La Niña at all, Funk says.
Armed with this new understanding, Funk in May 2016 found himself at USAID headquarters. A strong El Niño had just waned, and sea surface temperature trends suggested La Niña would follow. If it did form, he warned, FEWS NET's food analysts should prepare for sequential droughts in East Africa. A set of new seasonal climate forecasts from the National Oceanic and Atmospheric Administration echoed Funk's drought warnings. CHIRPS revealed that the October-December rains had failed. And, seeking to amplify their voices, FEWS NET and its peers at the United Nations and in Europe issued a joint alert, warning of potential famine.
By December of that year, food aid for half a million Somalis arrived. The next month, 1 million; by February 2017, 2 million. Thanks to the shipments and the many improvements East Africans had made in their own safety net, food prices didn't spike when the rains failed again. The warnings had worked.
Four years later, a different teleconnection is playing out, but the picture across Africa is equally grim. In February, in a small UCSB conference room, CHC climate scientist Laura Harrison pulled up a map of Africa. Although there was no El Niño or La Niña to influence events, the two Indian Ocean oscillations she and her colleagues had been watching were going strong.
The blob of hot water off the coast of Somalia turned out to be as hot as it's ever been, a half-degree warmer than a similar state in 1997. CHC had been right to forecast extensive rains in the Horn of Africa: Moist winds from the blob fueled drenching storms. The resulting flooding and landslides ruined 73,000 hectares of crops and killed more than 350 people. The storms also saturated arid regions, feeding lush growth that lured an unpredicted hazard to the region: a locust invasion. Hundreds of billions of locusts have chewed through rich farmland in Ethiopia's Rift Valley, while stripping pastures in Kenya and Somalia.
The blob of cold water south of Madagascar was doing the opposite. Just as the team expected, it had dried up rains across southern Africa. On Harrison's screen, CHIRPS data showed a red blob of anomalous dryness across Zimbabwe—rainfall was running 80% below average for the season. Short-term forecasts called for some rain, but it looked like it would come too late, Harrison said. “The crop has failed in a lot of those areas.”
On the phone from Botswana, Magadzire agreed. He had spent the day training people to use FEWS NET products, and his visiting Zimbabwean students reported lines for maize that lasted hours. To buy it, farmers were selling emaciated cows for a fraction of their value. “There is actually a huge shortage,” he said. In a few days, after the team hashed out its evidence, he'd argue the same to the FEWS NET social scientists who would integrate the data with economic and security analysis.
At the end of the month, FEWS NET staff compared their monitoring with that of their peers at the United Nations and Europe. The combined forecasts would go into the Crop Monitor for Early Warning, a monthly update provided by the University of Maryland that the G-20 group of rich nations began several years ago to unify famine warnings. Already, in response to previous reports, USAID had more than doubled its food aid to Zimbabwe, to $86 million. But even this increase may not be enough.
On 2 April, FEWS NET sent out a rare alert, stating crisis conditions were likely in southern Africa from April to August. Maize supplies would be short, with prices 10 times their normal level. By that time, another danger had arrived: the coronavirus pandemic. The resulting lockdowns in Zimbabwe and its neighbors could exacerbate risks for the neediest, putting them out of work and unable to afford maize. By the end of this year, FEWS NET warned, Zimbabwe could find itself in emergency conditions—one step away from famine.
Reflecting on his time at CHC, Funk is proud of his team and how it has tried to lessen the toll of famines. But he is clear-eyed about a problem that isn't going away—and may be getting worse, for reasons other than natural cycles. For the past 5 years, during a time of global economic growth, famine threats were still rising, Funk points out. Now, the coronavirus pandemic has the world teetering on recession. He worries that climate change will only exacerbate the inevitable conflicts over stressed croplands. “At the end of the day,” Funk says, “humanitarian crises are caused by humans.”
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