Heavy Rains From Climate Breakdown Driving Locust Plagues; More Frequent Indian Ocean Cyclones Key
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“This is not the first time that East Africa has seen locust upsurges approach this scale,” says Hamisi Williams, an FAO representative in Kenya, “but the size of the current situation is unprecedented in recent memory — sort of a 100-year storm.” A swarm of desert locusts (Schistocerca gregaria), numbering anywhere between 10 million and 100 million individuals, can fly up to 150 kilometers (90 miles) a day. Swarms have been known to migrate to Ethiopia and Somalia from as far away as India. As they move, the females lay eggs, leaving behind the nuclei of successive swarms that emerge a few weeks later.
Williams says climate change, which has affected storms and rainfall patterns in this region, is an important driver of locust population dynamics. Over the past three years, more frequent Indian Ocean cyclones have played a role in increased numbers of locusts. “In 2018, two cyclones dumped heavy rain on the uninhabited portion of the Arabian Peninsula known as ‘The Empty Quarter.’ There, locusts can breed and reproduce freely, undisturbed by humans. The locusts bred in the Empty Quarter for nine months, over three generations. That is the original source of the East Africa upsurge we are seeing now,” Williams told Mongabay.
These swarms can easily cross the narrow bodies of water that surround the Arabian Peninsula. They overflew the Red Sea, the Gulf of Aden, and the Arabian Sea to arrive in the Horn of Africa in 2019. There, says Williams, another spell of abnormally high rainfall in December 2019 triggered another spasm of reproduction.
Cyril Ferrand, head of the FAO Resilience Team East Africa, picks up the tale. “On Dec. 28, the swarms came in from Ethiopia and Somalia. The arid and semi-arid countries that they flew into were conducive for breeding, given the warm weather and moist soil caused by the heavy rains of 2019. These first generation ‘Kenyan born’ locusts grew [multiplied] 20 times, and their offspring would also grow 20 times larger, bringing the expected number of locusts from the original ones to 400 times bigger than the first which flew into the country.”
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https://news.mongabay.com/2020/06/changing-climate-creates-ideal-conditions-for-devastating-locust-swarms/
