The 2020-2021 La Nina event has passed its peak, but impacts on temperatures, precipitation and storm patterns continue, according to a new update from the World Meteorological Organization. Despite the general cooling influence of La Nina events, land temperatures are expected to be above-normal for most parts of the globe in February-April 2021.
La Nina appears to have peaked in October-November as a moderate strength event. There is a 65% likelihood that it will persist during February-April, with a 70% chance that the tropical Pacific will return to ENSO-neutral conditions by the April-June 2021 season, according to WMO‘s El Nino-La Nina Update.
La Nina 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 Nino Southern Oscillation.
“El Nino and La Nina 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 Nino and El Nino 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 Nina 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 Nina 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 Nina will influence global temperatures in 2021.