Triple-dip La Niña persists, prolonging drought and flooding

Geneva - The unusually stubborn and protracted La Niña event is likely to last until the end of the northern hemisphere winter, or southern hemisphere summer. 

The largest increase in probabilities for above-normal temperatures are along the Arctic coast of Asia, northern parts of central America, the eastern Maritime Continent, and New Zealand.

The first triple-dip La Niña, over three consecutive years, of the 21st century will continue to affect temperature and precipitation patterns and exacerbate drought and flooding in different parts of the world, according to the World Meteorological Organisation (WMO).

The WMO latest report just released says there is a 75 percent chance that La Niña will persist during to February and maybe even March.

There is a 55 percent chance of neutral conditions, neither El Niño or La Niña, emerging during February to April, increasing to about 70 percent during March to May, according to the WMO.

It is only the third time since 1950 that there has been a triple-dip La Niña. La Niña refers to the large-scale cooling of ocean surface temperatures in the central and eastern equatorial Pacific Ocean.

It is 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.

La Niña is a natural phenomenon. But it is taking place against a background of  human-induced climate change, which is increasing global temperatures, making the weather more extreme and affecting seasonal rainfall patterns.

The tropical Pacific has been in a La Niña state, with short interruptions, since September 2020. But this has only had a limited and temporary cooling impact on global temperatures. The last eight years are set to be the hottest on record and sea level rise and ocean warming has accelerated.

Already, more than 20 million people are highly food insecure in Kenya, Somalia and Ethiopia and some parts of Somalia may face the risk of famine by the end of the year.

It has been wetter than usual in southern Africa, northern South America, the maritime continent and eastern and southern Australia. More intense and longer monsoon rainfall in southeast Asia is associated with La Niña. Thus, Pakistan experienced devastating rains in July and August.

El Niño and La Niña are major but not the only drivers of the Earth’s climate system. Despite the stubborn La Niña in the equatorial central and eastern Pacific, widespread warmer than-average sea-surface temperatures elsewhere are predicted to dominate the forecast of air temperatures for into February.