Why El Niño is not to blame for record-breaking temperatures in 2023

At the time of writing, global temperature anomalies in 2023 continue to smash records. While the first daily global mean temperatures above 1.5°C were recorded in the summer, temperature anomalies during the autumn have been around 2°C. Alongside man-made carbon dioxide emissions, a phenomenon known as ‘El Niño’ is also taking a lot of the blame for the warming.

ABC Australia exclaimed that “It’s not just climate change”. The UK Daily Mail “pinned the blame on El Niño, a climate-heating natural weather event”. AP News blamed “climate change, El Niño and Russia’s war” for rising food prices around the world.

Whilst the widespread association of El Niño with global temperatures in media is relatively new – related probably to the alarming temperatures seen this year – blaming El Niño is not.

El Niño has provided a convenient scapegoat for failures in disaster risk reduction, mismanagement, and government corruption, where hydrometeorological disasters occurred during years with El Niño conditions. During the El Niño conditions of 1997-98, blaming El Niño in the US became something of a hobby. In California, people started displaying bumper stickers saying: ‘Don’t blame me, blame El Niño’.

As a named phenomenon with a vaguely Latin-flavoured name, El Niño provides a convenient scapegoat. With El Niño conditions declared when ocean temperatures cross a specific threshold, El Niño becomes something that is either here or it isn’t. El Niño is usually described as something that periodically ‘visits’, despite the fact that a declaration of El Niño conditions is based on a relatively arbitrary threshold in sea surface temperature.

The anthropomorphic nature of El Niño is strengthened by the presence of El Niño’s ‘sister’ La Niña. El Niño and La Niña thus form a gendered binary of male/female, hot/cold, wet/dry that is widely accepted in many cultures.

It is important that we recognise though that the badging of ocean-atmosphere variability in the tropical Pacific as El Niño is not inevitable.

The original El Niño phenomenon is a warm water current that occurs annually off the coast of Northern Peru, named by the local Catholic fishermen ‘El Niño’ (the Boy/Christ Child) due to its tendency to occur around Christmas. The fishermen did not distinguish between this annual current and the rarer, larger events, although later international scientists and commercial fisheries researching El Niño’s more intense manifestations had no interest in a local ocean current, so the meaning of the term changed over time.

It is difficult today to even define exactly what El Niño is. Each El Niño event is different, and whilst certain elements of El Niño can be forecast accurately there have been notable forecasting failures, particularly where El Niño does not behave as expected.

This should be kept in mind when El Niño is blamed for elevated temperatures. The phenomenon remains relatively poorly defined, and the badging of Pacific ocean-atmosphere variability as El Niño is in fact something of a historical accident. It would be better instead to think of the pattern of variability we currently call El Niño as a natural transfer of energy between the ocean and the atmosphere.

During normal years the trade winds blowing across the Pacific cause the warm surface waters to bunch up along the western boundary, with cooler waters across the eastern Pacific. During El Niño years the surface water flows eastwards, producing a larger area of warm water at the surface and allowing energy to be transferred to the atmosphere through evaporation. It is likely this has happened for millions of years, although it did not have a name before the twentieth century, and did not enter the public imagination until the late 1990s.

We should not, therefore, view record-breaking temperatures through the scapegoat of El Niño. Instead, they should be seen as a consequence of elevated greenhouse gas concentrations, primarily released through human activity. This produces a steady trend of warming that is projected onto various modes of natural variability, of which energy transfer in the Pacific (i.e. El Niño) is one.

El Niño-type processes will mean the rest of 2023 and into 2024 will likely be unprecedently warm, before temperatures will likely drop again the next year. Alarming as these records may be, they are not necessarily bad timing. The Paris Agreement was signed against a backdrop of unseasonably warm weather in Paris during the 2015-16 El Niño. It may be that the present global temperatures set the stage for a similar breakthrough. Either way, within the theatre of the COP, El Niño should be no more than a bit part, if present at all.