The return of the climatic phenomenon La Niña, which causes bad weather in the world, has begun and should last until next year -

/ AP / SIPA

She's back.

The World Meteorological Organization (WMO) announced the return of La Niña on Thursday.

This climatic phenomenon is causing bad weather in the world, has started and should last until next year.

According to the specialized agency of the UN, this episode should be "moderate to strong".

The last high intensity episode dates back to 2010-2011 and caused torrential rains in particular in Australia, South America and South Asia.

Reverse of the El Niño phenomenon

In 2008-2009, another episode of La Niña was blamed for freezing temperatures which had claimed dozens of victims across Europe.

The La Niña phenomenon is the inverse of the El Niño phenomenon and corresponds to the large-scale cooling of surface waters in the central and eastern equatorial Pacific, associated with variations in tropical atmospheric circulation.

La Niña will not stop global warming

But while La Niña generally has the effect of cooling the temperature on a global scale, it should not be expected to stop global warming.

Because now the cooling usually associated with La Niña is "more than offset by the heat trapped in our atmosphere by greenhouse gases", explained the Secretary General of the WMO, Petteri Taalas.

Thus, "the years in Niña are even warmer today than the years in strong Niño that we have known", he noted.

"Therefore", he concluded, "2020 is still on the way to become one of the hottest years on record and 2016 - 2020 is expected to be the hottest five year period in history."

Precipitation below normal in Africa and Asia

According to the WMO, it is very likely (90%) that tropical Pacific surface temperatures will continue to correspond to a La Niña anomaly until the end of the year, or even until the first quarter of 2021 ( 55%).

Seasonal forecasts indicate, according to the WMO, that several regions are expected to experience some of the most significant rainfall anomalies associated with the 2020 La Niña episode.

The regions of the Horn of Africa, Central Asia and Southeast Asia are expected to experience below normal precipitation, while it will be above normal in some islands in the Pacific and in the northern part of South America.

This La Niña episode coincides with a heavy rainy and planting season in much of East Africa, which is expected to experience drier than normal conditions.

"Added to the effects of the locust invasion, this situation is worrying and could increase food insecurity in the region," warns the WMO.

La Niña could also contribute to hurricane season

Maxx Dilley, deputy director of the organization, stressed during a press briefing that La Niña could also contribute to the particularly active hurricane season this year.

“There is a connection between La Niña, El Niño and the frequency of hurricanes.

El Niño tends to reduce the frequency while La Niña tends to encourage them, so La Nina could contribute to this active hurricane season that we are seeing, ”he said.

At the same time, Hurricane Zeta hits the southern United States.

In September, the meteorological services decided to use the Greek alphabet to name them, having exhausted the entire list of names initially planned for this season.

Maxx Dilley believes Zeta should be the last hurricane of the season, which normally runs from June to late October, although warming may allow later occurrences.

La Niña is expected to create drier-than-normal conditions in the southern United States and northern Mexico over the next three months.

“So we could go fairly quickly from hurricanes and floods to dry conditions,” said Maxx Dilley.

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