Geneva, June 10 (IANS) The World Meteorological Organization (WMO) on Friday of a high probability that the ongoing protracted La Nina 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 and possibly to the northern hemisphere fall and start of winter.
Some long-lead predictions even suggest that it might persist into 2023.
“If so, it would only be the third ‘triple-dip La Nina’ (three consecutive northern hemisphere winters of La Nina conditions) since 1950,” the WMO said in a global statement.
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 Nino, which is the warm phase of the so-called El Nino Southern Oscillation (ENSO).
The ongoing drought in the Horn of Africa and southern South America bear the hallmarks of La Nina, as does the above average rainfall in Southeast 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 Nina 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 Petteri Taalas.
“WMO is providing tailored support to the humanitarian sector – as witnessed by a recent multi-agency alert on the worsening drought in East Africa. Improved seasonal forecasts are pivotal in this because they help plan ahead and gain substantial socio-economic benefits in climate sensitive sectors like agriculture, food security, health and disaster risk reduction,” said Taalas.
“In addition to improving climate services, WMO is also striving towards the goal that everyone should have access to early warning systems in the next five years to protect them against hazards related to our weather, climate and water,” he reminded of the recent WMO announcement.
The current La Nina event started in September 2020 and continued through mid-May 2022 across the tropical Pacific. There was a temporary weakening of the oceanic components of La Nina during January and February 2022, but it has strengthened since March 2022.
WMO Global Producing Centres for Long Range Forecasts indicate that there is about a 70 per cent chance of the current La Nina conditions extending into boreal summer 2022, and about 50-60 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.