La Niña seen to linger
The World Meteorological Organization (WMO) says the ongoing La Niña event might persist into 2023.
There is a high probability that the protracted La Niña event - which has affected temperature and precipitation patterns and exacerbated drought and flooding in different parts of the world - will continue until at least August.
A new update from the World Meteorological Organization even suggests that it might persist into 2023. If so, it would only be the third “triple-dip La Niña” (three consecutive northern hemisphere winters of La Niña conditions) since 1950.
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 (ENSO).
The ongoing drought in the Horn of Africa and southern South America bear the hallmarks of La Niña, as does the above average rainfall in South-East Asia and Australasia and predictions for an above average Atlantic hurricane season.
However, all naturally occurring climate events now take place in the context of human-induced climate change, which is increasing global temperatures, exacerbating extreme weather and climate, and impacting seasonal rainfall and temperature patterns.
“Human induced climate change amplifies the impacts of naturally occurring events like La Niña and is increasingly influencing our weather patterns, in particular through more intense heat and drought and the associated risk of wildfires – as well as record-breaking deluges of rainfall and flooding,” says WMO Secretary-General Professor Petteri Taalas.
The current La Niña event started in September 2020 and continued throughout mid-May 2022 across the tropical Pacific.
There was a temporary weakening of the oceanic components of La Niña during January and February 2022, but it has strengthened since March 2022.
WMO Global Producing Centers for Long Range Forecasts indicate that there is about a 70 per cent chance of the current La Niña conditions extending into boreal summer 2022, and about 50 to 60 per cent during July-September 2022.
There are some indications that the probability may increase again slightly during the boreal fall of 2022 and early boreal winter of 2022-23.