GENEVA, Nov 30, 2022 (BSS/AFP) - The exceptionally-long La Nina, which has 
worsened drought and flooding around the globe, is set to continue into 
February or even March, the United Nations warned Wednesday.

The current La Nina weather phenomenon -- the cooling of surface temperatures 
which can cause widespread impacts on global weather conditions -- started in 
September 2020.

"The unusually stubborn and protracted La Nina event is likely to last until 
the end of the northern hemisphere winter/southern hemisphere summer," the 
UN's World Meteorological Organization (WMO) said.

"The first 'triple-dip' La Nina (three consecutive years) of the 21st century 
will continue to affect temperature and precipitation patterns and exacerbate 
drought and flooding in different parts of the world."

The WMO said there was a 75 percent chance that La Nina will persist during 
December-February, and a 60 percent chance during January-March.

It is the first triple-dip La Nina of the century and only the third since 
1950, the organisation said.

La Nina is the large-scale cooling of surface temperatures in the central and 
eastern equatorial Pacific Ocean. It normally occurs every two to seven 
years.

The effect has widespread impacts on weather around the world -- typically 
the opposite impacts to the El Nino phenomenon, which has a warming influence 
on global temperatures. Conditions oscillate between the two.

There is a 55 percent chance of neutral conditions (neither El Nino or La 
Nina) emerging during February-April 2023, increasing to about 70 percent in 
March-May, according to WMO.

- Limited cooling impact -

La Nina is a natural phenomenon, but it is taking place against a background 
of human-induced climate change, which is increasing global temperatures and 
making weather more extreme, the WMO said.

Despite La Nina's cooling effect, both 2022 and 2021 were warmer than any 
year prior to 2015.

"The tropical Pacific has been in a La Nina state, with short interruptions, 
since September 2020 -- but this has only had a limited and temporary cooling 
impact on global temperatures," said WMO chief Petteri Taalas.

"The past eight years are set to be the hottest on record and sea level rise 
and ocean warming has accelerated."

La Nina is usually associated with wetter conditions in some parts of the 
world, and drier conditions in others. 

"This persistent La Nina event is prolonging drought and flood conditions in 
affected regions," said Taalas. 

"The international community is especially concerned about the unfolding 
humanitarian catastrophe for millions of people in the Horn of Africa, driven 
by the longest and most severe drought in recent history."