Natural temperature increases in the Pacific Ocean follow a cycle of 2 to 7 years, and their duration ranges from 9 to 12 months. The effects of these episodes could extend beyond the climatic sphere. Vector-borne diseases such as malaria and dengue have been shown to spread over wider areas as temperatures rise. Scientists warn that El Niño, added to already catastrophic climate change, could exacerbate this situation.
Past instances of El Niño have seen an increase and spread of various infectious diseases in the tropics most affected by the phenomenon, according to Madeleine Thomson, an expert on climate impacts at the Wellcome Trust charity.
This increase is linked to two effects of El Niño: abnormal rainfall that favors the reproduction of vectors such as mosquitoes and higher temperatures that accelerate the transmission of infectious diseases.
In 1998, an El Niño event coincided with a significant outbreak of malaria in the Kenyan highlands. The arrival of El Niño could drastically increase the probability of setting temperature records and generating extreme heat in many regions of the world, said Petteri Taalas, secretary general of the World Meteorological Organization (WMO).
Heat waves are “silent killers” that actually cause more deaths than other violent weather events, according to Gregory Wellenius, director of a center for climate and health at Boston University. Last summer, more than 61,000 people died in Europe due to heat, without the influence of El Niño.
July 2023 has already become the warmest month on record, although the full effect of El Niño on global temperatures generally manifests itself a year after the onset of the phenomenon.
The presence of El Niño in a year can increase the chances of crop failures in regions such as South and Southeast Asia, which could affect the global production of rice, a plant highly susceptible to weather conditions.
The Panama Canal, through which 6% of global maritime trade passes, announced restrictions due to low rainfall exacerbated by El Niño, which could result in revenue losses of up to $200 million.
A study published in the journal Science in May estimated that El Niño events have caused more than $4 trillion in damage to the global economy in subsequent years. According to this research, the impacts of El Niño and climate change are expected to generate economic losses of $84 billion in the 21st century.