Weak La Niña may return: WMO
WMO – A weak La Niña event may re-emerge later in 2021 for the second consecutive year, with the risk that forecast precipitation patterns may exacerbate existing drought in some parts of the world and increase the risk of heavy rainfall and flooding in others, according to the latest forecast from the World Meteorological Organization. While La Niña typically has a cooling influence, temperatures over land areas are expected to be above average between September and November, especially in the northern hemisphere.
The latest El Niño/La Niña Update from the WMO suggests that either the cool side of ENSO-neutral conditions continue or that La Niña conditions return near the end of the year. There is a 60% chance of ENSO-neutral and 40% for La Niña for September-November, and equal chances of ENSO-neutral and La-Nina re-emergence in October-December and November-January. The El Niño/La Niña outlook favors ENSO-neutral again in 2022.
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).
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 impacting seasonal rainfall 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,” said WMO Secretary-General Prof. Petteri Taalas in a press release.
“We have seen this with devastating and tragic effect in the past few months in nearly all regions of the world. Climate change is increasing the severity and frequency of disasters,” he said.
“Improved early warnings and disaster risk management means that we are better at saving lives, but the socio-economic and humanitarian impacts are spiralling in the form of worsening food insecurity, more displacement and migration and the potential for unrest,” said Taalas.
