If La Nina continues, expect more droughts and floods

The climate phenomenon known as La Nina triggers a chain reaction between weather patterns around the world. This can lead to more droughts in some places even as floods and cyclones occur in others. La Nina occurs when the surface of the Pacific Ocean along the equator cools and the atmosphere above it reacts. Usually, this happens once every few years. However, the persistence of the latter poses the possibility that the Northern Hemisphere will experience its third consecutive La Nina winter, which is rare.

1. How strange is this?

Since 1950, according to US records, La Nina has occurred in three consecutive years only twice, in 1998-2001 and 1973-1976. As far as anyone knows, there hasn’t been a La Nina four times, so forecasters believe the current wave will fade in early 2023 after it reaches its peak.

2. What could the third year of La Nina mean?

For California, the largest agricultural state in the United States, and for the soybean and corn growing regions of Argentina and Brazil, it could mean another year of drought. In Australia, it could bring another round of flooding across Queensland, Victoria and New South Wales, where rising waters generated at least $3 billion in insurance claims in early 2022. The price of a cup of coffee could rise if drought hits farmers in Brazil while floods hit Those in Vietnam and Colombia. Sugar for sweetening may cost more if the cane used to make it is stressed from the lack of rain. Across the Atlantic, there could be more hurricanes than usual because the La Nina there reduces wind shear, which is one of nature’s ways to put an end to devastating storms. In 2020, the Atlantic recorded a record 30 storms, and in 2021 there were 21 storms.

3. How is La Nina related to El Nino?

La Nina is part of a larger cycle known as the El Nino Southern Oscillation. The ENSO, as scientists call it, consists of El Nino – Peruvian fishermen named it the Christ Child in the seventeenth century when they noticed a warming tropical Pacific Ocean near Christmas in some years, La Nina, and a neutral phase in between.

4. What causes this cycle?

El Niños occur for unknown reasons, although some scientists believe it is a way for Earth’s atmosphere to shed heat into space. They begin faintly in the trade winds that push the warm waters from the sun in the tropical Pacific to a hill in the west. Part of that water flows eastward, making the eastern Pacific Ocean hotter. This phenomenon affects larger air currents, diverting moisture-bearing storms away from some places, such as Indonesia and Africa, and towards other places, including Argentina and Japan. When the heat from El Nino runs out, the ocean begins to cool. Initially, the Pacific Ocean falls into a state between the two extremes, the neutral phase. If cooling continues and sea surface temperatures fall below normal, La Nina will occur. Everything tends to play out every two to seven years. However, as has been evident since 2020, one end of the pattern could dominate for some time. The Atlantic and Indian Oceans have similar events, but their events do not have a far-reaching effect to those of the massive Pacific Ocean.

5. Does climate change affect the cycle?

Some early models suggested that as the Earth warmed, the number of El Niño events would rise. However, this does not appear to have happened. So far this century, La Nina has dominated the course. Weather experts say it will take more research to find out why. One theory is that smoke from bushfires in Australia in 2019 and 2020 is a factor, according to Gerald Mehl, chief scientist at the National Center for Atmospheric Research in the United States. US government meteorologist Tom DeLiberto noted years ago that there are many variables influencing El Nino and its ramifications, and isolating the role of global warming may not be possible.

More stories like these are available at bloomberg.com

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