“Insect Apocalypse”: Climate change reason behind locust outbreak?
Scientists link locust attacks, which damaged large farmland areas in Gujarat and Rajasthan in India, with climate change, warning that conditions like these will prevail if emissions continue to rise.
A locust outbreak -- an insect apocalypse -- has devastated farmlands and livelihood in Gujarat and Rajasthan in India, along with those in countries in Africa, the Middle East and South Asia. The invasion is said to be one of its kind in the past seven decades.
Now, experts connect it with global warming and climate change.
Although locust attacks are a seasonal phenomenon, favourable conditions like a good rainfall, greenery and moisture had fuelled the assaults in the infested regions.
“The West Indian Ocean, including the Arabian Sea, was warmer than usual during the last two seasons. This is largely due to a phenomenon called Indian Ocean Dipole (IOD), and also due to the rising ocean temperatures associated with global warming,” says Dr Roxy Koll Mathew at Indian Institute of Tropical Meteorology, Pune.
Indian Ocean Dipole (IOD) refers to the difference in water temperature between opposite sides of the Indian Ocean. The IOD is a primary driver of climate conditions stretching from Africa to Australia.
“Heavy, prolonged rains over the west coast of India (including Rajasthan) during the latter half of the monsoon— and unusually strong cyclones during the post-monsoon season— may have links with these warm ocean temperatures in the west Indian Ocean region.”
Unusual weather conditions, especially the widespread heavy rains, are a major factor contributing to the locust attacks. Heavy downpour leads to the growth of vegetation in arid areas, providing locusts with the conditions needed to develop and reproduce, according to the World Meteorological Department (WMO).
With weather conditions advancing the insect growth, the swarms are expected to worsen over the coming months as the locusts feed on the new season's crops.
The UN Food and Agriculture Organisation (FAO) has described this unprecedented threat as "extremely alarming" as it affects the areas already vulnerable to the impacts of climate change.
According to the FAO, a single locust swarm covered an area of 40km by 60km, consumed as much food in a single day as 85 million people in Kenya, while in Ethiopia swarms have covered more than 429 km sq.
As wet seasons increase, even worse locust attacks could follow. This could damage the livelihoods of one-tenth of the world's population, according to the FAO.
IOD and climate change
The positive phase of the IOD in 2019 was the strongest for six decades. This change in the pattern of ocean temperatures led to severe rainfall in vulnerable regions, as well as contributed to the unusually dry conditions in Australia that drove the current bushfires.
Academic studies have found that strongly positive phases of the IOD have happened more often in recent decades and that climate change is behind the increase.
As greenhouse gases continue to heat the ocean and the atmosphere, extreme events caused by the IOD are predicted to become increasingly common.