Locust outbreaks in the Horn of Africa are linked to the changing climate

Since 2018, swarms of desert locusts have devoured vital crops and vegetation in the Horn of Africa, and scientists are drawing ominous links between this new reality, the warming climate and increasingly extreme weather. 

“Unusually heavy and widespread rainfall has made this plague more serious, impacting countries that had previously been hardly affected, such as Kenya, South Sudan and Uganda,” says Christiaan Kooyman, a scientific advisor and biopesticide expert in Kenya. “It is fairly certain that climate change has contributed.”

The locust plagues are linked to powerful recent cyclones in the fast-warming western Indian Ocean, with the heavy rains, strong winds and soaked land creating ideal conditions for desert locusts to breed and spread.

The frequency and intensity of these cyclones are increasing. A recent commentary in the journal Nature Climate Change noted that 2019 was a record-setting year for the number of tropical cyclones in the Indian Ocean, with eight making landfall. As part of this, the capital of Djibouti received the equivalent of two normal years’ worth of rain in four days. Across the Red Sea, desert lakes formed in a barren, uninhabited region of Saudi Arabia known as the “Empty Quarter.”

Concurrently, the frequency and severity of the locust outbreaks are also on the rise as the species transform dramatically under wet conditions, changing from solitary creatures to social ones that breed exponentially. Kenya, for instance, experienced its worst locust infestation in 70 years in 2019 and East Africa its worst desert locust crisis in 25 years, according to the Food and Agriculture Organization of the United Nations (FAO).

“While desert locusts are an age-old threat, we fear something is changing,” the FAO said in a statement. “If the current trend of increased cyclones continues, then the Horn of Africa is likely to face more locust outbreaks in the future.”

Drawn in by the vegetation and greenery resulting from the rains, desert locusts reproduce and disperse. With wet, warm and sandy soil optimal for laying eggs, several generations of desert locusts have been bred since 2018. The mature winged adults multiply rapidly and driven by the wind can migrate widely in search of food, flying upwards of 150 kilometers (90 miles) in a day. On the ground, the voracious pests, a part of the grasshopper family, can destroy huge amounts of crops. One square kilometer can hold a swarm of 40 to 80 million desert locusts, and in a single day a swarm can eat the same amount as roughly 35,000 people or six elephants.

Faced with an onslaught of desert locust swarms after a November 2020 cyclone led to an atypically wet December, local communities, NGOs and international and government agencies have fought back both in the air and in the field. The FAO and other groups have partnered with local aviation companies and scouts on the ground to spray pesticides in infested areas. The application of these chemical pesticides has also led to concern about the long-term impact on the environment. Rural farmers have also dug up locust eggs to expose them to birds and other predators, created their own organic pesticides extracted from oil of the neem tree to spray on locusts, and banged on drums and other containers to disturb them. 

But these responders face a daunting battle against the swarms, particularly the species Schistocerca gregaria due to its clustering, gregarious nature, which spurs its rapid rate of reproduction. Already, the FAO estimates more than 1.3 million hectares of land with locust infestations have been treated since January, and air and ground control measures continue to roll out. Aid too has been distributed to rural communities hard-hit by the swarms that are now facing a food crisis in addition to the ongoing socioeconomic and public health challenges of the COVID-19 pandemic. 

Control operations and an anticipated return to drier conditions due to light-to-moderate spring rains are helping to curb the damage from this year’s desert locust outbreak. But officials are remaining vigilant as some new swarms continue to form in advance of the spring planting season in early April. 

Looking ahead, experts are urging fixes to systems designed to prepare for and respond to these locust outbreaks. “There is not always long-term thinking around environmental protection with something like desert locusts,” says Monique Bennett, a senior researcher with Good Governance Africa. “There is a good scientific understanding of how to control for locusts, but lack of membership payment by countries within the DLCO-EA means there isn’t sufficient preparation when locusts break out. Governments do not invest in research and readiness when it does arise.”

Bennett says more regional coordination and funding for preventive measures and regional oversight is needed, particularly for the Desert Locust Control Organization for Eastern Africa (DLCO-EA). She also stressed the importance of investing in research and technology, developing early warning systems and stockpiling resources in advance of emergencies. Such preparations can lessen the costs of responding to outbreaks and the impact on food security and livelihoods in a region already experiencing acute hunger and other vulnerabilities.

“The predicted trend is that years of abundant rainfall will increase, though droughts will not likely disappear,” says Kooyman. “It is therefore to be expected that plagues will occur more frequently at least in the central region [of Africa]. If funding were available in time, any locust upsurges could be nipped in the bud by good surveillance and control of locust groups and swarms.”