WMO declares onset of El Nino, warns surge in global temperatures

El Nino conditions have developed in the tropical Pacific for the first time in seven years, setting the stage for a likely surge in global temperatures and disruptive weather and climate patterns, according to a new report issued by the World Meteorological Organization (WMO) on Wednesday.

WMO forecasts that there is a 90 per cent probability of the El Nino event continuing during the second half of 2023, and it is expected to be at least of moderate strength.

“The onset of El Nino will greatly increase the likelihood of breaking temperature records and triggering more extreme heat in many parts of the world and in the ocean,” said WMO Secretary-General Prof. Petteri Taalas, in a statement.

El Nino occurs on average every two to seven years, and episodes typically last nine to 12 months. It is a naturally occurring climate pattern associated with warming of the ocean surface temperatures in the central and eastern tropical Pacific Ocean.

But it takes place in the context of a climate changed by human activities.

The UN agency said that since February, monthly average sea surface temperature anomalies in the central-eastern equatorial Pacific have warmed significantly, rising from nearly half degree Celsius below average (-0.44 in February) to around half degree Celsius above average (+0.47 in May).

In the week centred on June 14, the warm sea surface temperature anomalies continued to increase, reaching a value of +0.9 degrees Celsius.

The collective evidence from both oceanic and atmospheric observations strongly points towards the presence of El Nino conditions in the Pacific, the WMO said.

However, some uncertainty remains because of only weak ocean-atmosphere coupling, which is crucial for the amplification and sustenance of El Nino.

It is anticipated that it will take approximately another month or so to witness a fully established coupling in the tropical Pacific.

“As warmer-than-average sea surface temperatures are generally predicted over oceanic regions, they contribute to widespread prediction of above-normal temperatures over land areas. Without exception, positive temperature anomalies are expected over all land areas in the Northern and Southern Hemisphere,” said the UN agency’s latest update for July, August and September 2023.

“The declaration of an El Nino by the WMO is the signal to governments around the world to mobilise preparations to limit the impacts on our health, our ecosystems and our economies,” Taalas said.

“Early warnings and anticipatory action of extreme weather events associated with this major climate phenomenon are vital to save lives and livelihoods,” he added.