Giant Locust Swarms Could Expand to New Areas With Climate Change, Study Suggests

In the coming decades, erratic periods of rain and drought could create new hot spots for the ravenous grasshoppers in west India and west central Asia, threatening crops and food security

A close-up, hovering just a few inches above the ground, of dozens of locusts sitting in the dirt or flying in the air. The landscape is dry and dusty, with hardly any vegetation other than dead grass or dirt.
A single locust swarm can comprise between four billion and eight billion individual insects. ruvanboshoff via Getty Images

Locust swarms could soon expand to new regions in south and west central Asia, as the erratic weather patterns brought on by burning fossil fuels create prime conditions for the insects, a recent study suggests.

Between 2065 and 2100, desert locusts’ range could expand by as much as 13 to 25 percent as a result of cyclical droughts—providing the hot, dry weather in which locusts thrive—and occasional heavy rains, which allow their eggs to incubate in damp soil.

The food security and livelihoods of millions of people in India, Afghanistan, Turkmenistan and Iran would be under threat, the researchers argue in their paper, published last week in Science Advances. In those countries in particular, they estimate new hot spots of locust swarms to emerge as the world is altered by climate change.

“Failure to address these risks could further strain food production systems and escalate the severity of global food insecurity,” study co-author Xiaogang He, a hydrologist and environmental policy expert at the National University of Singapore, tells Carlos Mureithi of the Associated Press (AP).

Swarm Of Locusts DEVOUR Everything In Their Path | Planet Earth | BBC Earth

Desert locusts, a kind of migratory grasshopper, are often solitary insects. But when drought reduces available vegetation in their habitat, locusts come together and fly in one of the world’s most populous migrations in search of food, moving in groups that can comprise between four billion and eight billion individuals. The air becomes thick with the insects, as they cover up to 90 miles a day across multiple countries, taking up an area of 460 square miles. Even just a small swarm of 80 million individuals can eat enough crops in a single day to feed 35,000 people. As a result, the United Nations’ Food and Agriculture Organization calls them “the most destructive migratory pest in the world.” Typically, they inhabit regions of Africa, the Middle East and Southwest Asia.

The most severe locust crisis in recent history came to East Africa in 2019 and 2020, when both drought and extreme rainfall made conditions ripe for locust breeding and growth. And already, irregular weather patterns in other parts of the world have spurred locust swarms where they traditionally haven’t been.

In 2019, a swarm hit the southern Arabian Peninsula, which was “previously unsuitable for breeding due to vegetation conditions,” Martin Husemann, the science director of the State Museum of Natural History in Germany who was not involved in the study, tells Inside Climate News’ Bob Berwyn. And Kenya, which in the late twentieth century saw a limited number of swarms, has since become one of the world’s hot spots.

A photograph of the blue sky, filled with millions of locusts moving so quickly and unfocused that each appears as a brown blur
Millions of Australian plague locusts swarm in the sky in 2007. CSIRO via Wikimedia Commons under CC BY 3.0 DEED

The team of researchers mathematically modeled how precipitation events, temperature, wind and soil moisture might affect the movement of swarms over large areas. Simultaneously, they modeled how global warming would affect weather patterns in the coming decades. Their calculations revealed a high probability that synchronized “hot spots” of locust activity would pop up in seemingly dissimilar locations at the same time—such as in Pakistan and Algeria, or in India and Morocco—due to weather irregularities.

The potential loss of crops could severely disrupt local, regional and global food networks.

“Given that these countries often serve as global breadbaskets and are already grappling with climate-driven extremes like droughts, floods and heat waves, the potential escalation of locust risks in these regions could exacerbate existing challenges,” He tells the New York Times’ Raymond Zhong.

Cyril Piou, a plant researcher and ecologist at the Center for Biology and Management of Populations in France who was not involved in the study, tells Inside Climate News the team did not sufficiently account for local pest control measures, which have decreased the impact of locust swarms over the past few decades. They also did not collaborate with many researchers in the affected countries.

“There are many scientists in these countries that actually know a lot about locust ecology and management,” he says to the publication. “And [the researchers] could have gotten some grasp of this information to avoid arriving at conclusions… without knowing what’s happening already on the ground.”

A close-up photo of about a half-dozen locusts sitting on the front grill of a white car
Locusts sit on the front grill of a car in Israel in 2004. Niv Singer via Flickr under CC BY-SA 2.0 DEED

Piou adds to Inside Climate News that predicting rainfall is an inexact science, and estimating locust swarm activity based on these models may be a bit presumptuous.

But many researchers, including the study authors, agree that a major step to curb the impact of locust swarms is the strengthening of international partnerships and communication—leveraging emergency funding, weather information, historical records and other sources to prepare for and contend with the insects.

“The desert locust crisis is less about the insect and more about conflict and insecurity among people,” wrote Jody Green, an entomologist at the University of Nebraska-Lincoln, who was not involved in the study, in a 2022 blog post for Entomology Today. “It is a story that demonstrates what can happen when countries do not coordinate enough among one another.”

Get the latest stories in your inbox every weekday.