Have you ever wondered what El Niño is? No, it’s not a little-known actor you may have heard of, but rather a naturally occurring climate pattern, which is linked to the warming of ocean surface temperatures in the eastern and central tropical Pacific Ocean. It is also one that we could expect to observe this year in the UK. The name translates to “little boy” in Spanish, in honour of the Christ child. It is believed that it was selected based on the time of year (around December) during which these warm-water events were historically spotted off the coast of South America.
It is a pattern which occurs on average, every two to seven years. The episodes last around nine months to one year.
In simple terms, the condition is known to occur when surface water in the equatorial Pacific becomes warmer than average and east winds blow weaker than normal. The instance of the event was a weak one and occurred in 2018-2019.
An instance of El Niño is declared when sea temperatures in the tropical eastern Pacific rise 0.5 °C above the long-term average. You may have also heard about La Niña, which is an oceanic and atmospheric phenomenon that is the colder relative of El Niño. La Niña causes the jet stream to move northward and to weaken over the eastern Pacific. During La Niña winters, the South sees warmer and drier conditions than usual.
According to the World Meteorological Organization (WMO), there is an increasing probability of it developing this year. La Niña has now ended after a three-year run and the tropical Pacific is at the moment in an ENSO-neutral state (The El Niño-Southern Oscillation), meaning that it is neither El Niño nor La Niña. According to the WMO, there is a 60% chance for a transition from ENSO-neutral to El Niño between May and July. This will increase to about 70% between June and August, and then 80% between July and September, according to the latest Update.
At this stage there is no indication of the strength or duration of El Niño but it can sometimes bring warmer winters to the UK and Europe. Some sources believe that the UK could face record-breaking seasonal temperatures as a result.
Geographically, it has an impact on weather systems around the globe, triggering disruptions in temperature, rainfall and winds, which can mean floods, droughts, crop failures, and food shortages. It is believed that scientists consider 1.5 degrees of global warming to be the Earth’s “tipping point.” Beyond this, the chances of disruptive conditions increases significantly. A strong El Niño could create this effect and have wider implications on the global economy.