La Niña passes peak, but effects continue – UN

MANILA, Philippines — The 2020-2021 La Niña event has passed its peak, but impacts on temperatures, precipitation and storm patterns continue, according to the United Nations weather agency.

In a new update from the World Meteorological Organization (WMO), land temperatures are expected to be above-normal for most parts of the globe in February-April 2021 despite the general cooling influence of La Niña events.

La Niña appears to have peaked in October-November as a moderate strength event. There is a 65 percent likelihood that it will persist during February-April, with a 70 percent chance that the tropical Pacific will return to ENSO-neutral conditions by the April-June 2021 season, the WMO’s El Niño-La Niña update showed.

La Niña refers to the large-scale cooling of the ocean surface temperatures in the central and eastern equatorial Pacific Ocean, coupled with changes in the tropical atmospheric circulation, namely winds, pressure and rainfall. It usually has the opposite impacts on weather and climate as El Niño, which is the warm phase of the so-called El Niño southern oscillation.

“El Niño and La Niña are major drivers of the Earth’s climate system. But all naturally occurring climate events now take place in the context of human-induced climate change, which is increasing global temperatures, exacerbating extreme weather, impacting seasonal rainfall patterns and complicating disaster prevention and management,” said WMO Secretary-General professor Petteri Taalas.

“Thanks to our ability to predict La Niño and El Niño events in advance, the WMO community has been able to strengthen its support to governments, the United Nations and stakeholders in climate sensitive sectors to mobilize preparations and save lives,” he said.

La Niña has a temporary global cooling effect. But this was not enough to prevent 2020 from being one of the three warmest years on record.

La Niña and El Niño effects on average global temperature are typically strongest in the second year of the event, but it remains to be seen to what extent the current La Niña will influence global temperatures in 2021.

Large parts of Southeast Asia have shown a typical La Niña response with significantly above normal rainfall totals over the last few months.

“This trend is likely to continue, particularly to the east of the region,” WMO said.