“A triple episode”: World Meteorological Organization warns that unprecedented climate phenomenon will affect Chile for the first time in 20 years

The World Meteorological Organization (WMO) set off the weather alarmsafter warning that this year there will be the third consecutive episode of the La Niña phenomenon.

According to the meteorological agency of the United Nations (UN), there is a 70% chance of La Niña extending into September and November. There is even a 55% chance that it will occur until February 2023, added the WMO.

The actual “triple episode” of La Niña started in September 2020. “The last time this happened (that there were three consecutive years with the presence of the phenomenon) was between 1999 and 2001 (more than 20 years ago)″points Raúl Cordero, climatologist of the University of Santiago, realizing the unprecedented nature of this phenomenon.

According to the WMO, all naturally occurring weather events now occur in the context of anthropogenic climate change, causing a rise in global temperatures, exacerbating extreme weather and climate eventsand alters the configuration of seasonal temperatures and precipitation.

Lake Peñuelas, located in the Valparaíso Region. PHOTO: Agency One

Its recurrence helps explain why Chile continues to experience a megadrought that has already lasted for more than a decade. This is because the presence of La Niña It is always associated with a lack of rain and the consequent drought. Its appearance usually begins in October, and ends in April, as long as it rains. In general, in Chile it does not appear in winter.

Cordero explains that with the announcement of its presence for the third year, “we will complete three consecutive summers marked by the influence of La Niña in the tropical Pacific. It is not strange that it is recorded consecutively, but it is rare that he does it for three years in a row. It has been more than two decades since three events like this have been recorded.”

“It is exceptional that an episode of La Niña lasts for three consecutive years. Its cooling effect is temporarily slowing the rise in global temperatures, but it will not stop or reverse the long-term warming trend.” stated in a statement WMO Secretary General Professor Petteri Taalas.

According to Cordero, “La Niña corresponds to the cold phase of an oscillation and the surface temperature of the tropical Pacific, off the coast of Ecuador and Peru. The temperature in that area is currently dropping and will probably peak at the end of the year. It is expected that during the first quarter of next year the temperature in this area will begin to rise towards values ​​closest to those considered normal or, in climatological jargon, neutral”.

Probabilistic predictions of surface air temperature and precipitation for the September-October 2022 season. The reference period is 1993-2009. Credit: WMO

Cordero explains that the effects of La Niña depend on the region. “During the austral summer it is associated with low rainfall in Patagonia, moderate temperatures in the central zone, and it can intensify the altiplano winter in the extreme north of the country. On the other hand, it tends to strengthen or attenuate some of the effects of global warming. For example, in the central zone its moderating effect on temperatures probably make next summer not as hot as it could be if you weren’t here.”

This could also moderate the forest fire season. “This does not mean that next summer will not be hot. But without La Niña it could in terms of maximum temperature be much worse”, he adds.

In addition, the phenomenon affects temperatures and rainfall in much of the world.. “Between southern California and the south central zone of Chile, it is associated with low rainfall and drought. However, its effects go far beyond the Pacific basin, and can also affect rainfall in southern Brazil and, via anomalies in wind patterns, can intensify the hurricane season in the Atlantic”, explains the academic. of the Usach.

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