Climate Change Makes Biblical Plagues a More Regular Threat to Farmers

Locust swarms can be devastating to farmers and, potentially, the food supply.

(Photo: Samuel Aranda/Getty Images)

Jan 26, 2016· 3 MIN READ
Tove Danovich is a journalist based in Portland, Oregon.

A swarm of locusts that covers the land and skies, devours crops, and leaves cattle without grass for grazing is a plague worthy of the Bible. In Argentina, where farmers have reported locust clouds “four miles long and nearly two miles high,” according to The New York Times, the threat is all too real.

The country is facing the worst infestation of locusts in 60 years, and most believe there is no stopping the swarm at this point, only a possibility of lessening its effects. Fumigators have been attempting to kill young locusts that are not yet able to fly. In a little more than a week, the locusts are expected to “mature into voracious flying swarms in search of food,” the Times wrote. The Rural Confederation of Argentina told La Nacion that 700,000 hectares of farmland have already been affected and could easily spread to millions if immediate action isn’t taken. Farmers in the surrounding area grow sunflower and cotton, or manage grasslands for grazing livestock. But if the swarm takes to the air, there’s no telling where it might land and what damage it could do.

While Argentina is facing a very clear and present danger, there’s a looming threat of a swarm hitting other countries too—a threat that may be intensifying. “Locust are becoming even more dangerous in the context of exceptional weather events associated to climate change,” according to the Food and Agriculture Organization of the United Nations, which notes that the high incidence of drought in the 21st century has also worsened the impact of locusts in Africa. Drought may decrease locust numbers, but the FAO warns that higher temperatures could “shorten the incubation and maturation periods and lead to a rise in the number of locust generations in a year.” So not only will there be an increasing possibility of locust swarms, but the intensity of those swarms is likely to rise. Together, the FAO writes, a “very small” swarm consumes as much food as 35,000 people eat per day.

Locusts, a type of grasshopper, are relatively innocuous, solitary insects most of the time. But extreme weather events, such as those caused by climate change and El Niño, have the potential to trigger swarms. There are a number of potential environmental changes that lead to swarming, but most often the behavior has been tied to a period of flooding in otherwise arid regions, leading to plant growth that provides a hospitable environment for the locust population to boom. When dry weather eventually returns, the habitat shrinks, and the inflated population of locusts is pushed closer together.

Rather than eating in the every-locust-for-himself approach that is the norm for the insect, the cramped conditions result in a chemical change that turns the solitary insects into gregarious team players. Young locusts can’t fly. They develop wings as adults. Once they mature and tens of millions of locusts take to the air in unison, they form a giant black cloud that settles onto farmland and fields, eating everything in its path. It’s not the appetite of the individual locusts so much as the targeted buffet-style approach the swarms implement that creates such an utter disaster for farmers. They also change color from dark brown or red to bright orange and pink before swarming (the exact switch depending on the species). Humans may get the winter blues, but climate and weather effects on locusts constitute a full metamorphosis.

The most worrisome variety is the desert locust, which can “live and breed under various ecological and climatic regimes in vast areas covering 29 million square kilometers” and covering parts of 60 different countries in Africa, the Middle East, and Asia, according to the FAO. Their swarm area constitutes more than 20 percent of the world’s land surface. “During plagues,” the FAO added, “the desert locust has the potential to damage the livelihood of a tenth of the world’s population.”

Even though the desert locust is the heartiest species, all locust swarms can migrate quickly, covering hundreds of miles of land per day. This makes preventing swarms not just the responsibility of the nation where the swarm originated, but the international community too. The only way to combat locust swarms is through preventive measures such as monitoring and pesticides. But predictive models aren’t reliable where locusts are concerned.

Still, when it’s clear that young locust populations are growing, it’s important to reduce their numbers. But so far the international community has not been effective in its attempts. The best way to stop a plague is early spraying of juvenile locusts with small amounts of pesticides. But as locusts get closer to swarming, their numbers make this a more difficult and expensive proposition. Once the insects have taken to the air, aerial spraying is the only way to combat the plague.

The response to numerous swarms in Africa has succeeded only at enormous cost owing to initial underfunding and late implementation. A 2003–2005 outbreak would have cost only $3.3 million per year to prevent, according to the FAO. Instead, responding to the outbreak after the swarm had amounted to $570 million plus untold additional funds in crop damages and economic losses. In November, the FAO warned that recent weather in the northwest Africa, the Horn of Africa, and Yemen had created the perfect breeding ground for locusts and strongly suggested preventive measures be put in place. But the response has been slow yet again.

All signs point toward locust swarms becoming more prevalent, making it all the more important that preventive measures become the norm.