Geneva – A warming El Niño event may develop in the coming months after three consecutive years of an unusually stubborn and protracted La Niña, according to a new report from the World Meteorological Organisation (WMO).
However, while the return of El Nino is considered likely this will be proceeded by a period of neutral conditions during March-May. The likelihood of these stable conditions continuing beyond May decreases slightly but remains high.
The chances of El Niño developing, while low in the first half of the year, gradually increases in May-July. Long-lead forecasts for June-August indicate a much higher chance (55 percent) of El Niño developing but are subject to high uncertainty associated with predictions this time of the year.
The first triple-dip La Niña of the 21st century is finally coming to an end. La Niña’s cooling effect put a temporary brake on rising global temperatures, even though the past eight year period was the warmest on record.
If the world now enters an El Niño phase, it is likely to fuel another spike in global temperatures.
2016 is currently the warmest year on record because of the combination of El Niño and climate change. There is a 93 percent likelihood of at least one year until 2026 being the warmest on record, and a 50:50 chance of the global temperature temporarily reaching 1.5°C above the pre-industrial.
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. It usually has the opposite impacts on weather and climate as El Niño in affected regions.
La Niña has been associated with the persistent drought in the Greater Horn of Africa and large parts of South America as well as above average rainfall in South East Asia and Australasia.
El Niño and La Niña are a natural phenomenon. But it is taking place against a background of human-induced climate change, which is increasing global temperatures, affecting seasonal rainfall patterns, and making our weather more extreme.
A return to near-normal conditions is predicted for the equatorial central and eastern Pacific, and warmer than average sea surface temperatures are generally predicted over other oceanic regions. This contributes to widespread prediction of above-normal temperatures over land areas.
Even though La Niña is coming to an end we are likely to see latent impacts for some time to come and therefore some of the canonical rainfall impacts of La Niña may still continue. The lingering impacts of multi-year La Niña is basically due to its long duration, and continuous circulation anomaly, which are different from the single-peak La Niña event.
