What is El Nino? The weather event explained, how it will affect the UK and what it means for global warming
There is a two-in-three chance the world will temporarily hit a key warming limit within the next five years, the United Nations weather agency said on Wednesday.
The World Meteorological Organisation (WMO) forecasts a 66 per cent likelihood that between now and 2027, the globe will have a year that averages 1.5ºC warmer than the mid 19th century.
That number is critical because the 2015 Paris Climate Agreement set 1.5ºC as a global guardrail in atmospheric warming, with countries pledging to try to prevent that much long-term warming if possible.
This likely would only be a fleeting flirtation with the internationally agreed-upon temperature threshold, however, as scientists expect a temporary burst of heat from El Niño — a naturally-occurring weather phenomenon — to supercharge human-caused warming from the burning of coal, oil and gas to new heights.
What is El Niño?
El Niño is part of a natural climate pattern known as El Niño Southern Oscillation. Under El Niño sea surface temperatures, particularly in the tropical central and eastern part of the Pacific Ocean, rise. This affects the climate not only in this region, but across the world.
An El Niño phase can last a few years. This then gives way to La Niña, which is essentially the opposite. Sea temperatures cool and this has a knock-on effect on the general climate. El Niño is Spanish for “the boy”, while La Niña translates as “the girl”.
The effects of El Niño often peak during December. The name is thought to have originated as “El Niño de Navidad“ centuries ago when Peruvian fishermen named the weather phenomenon after the newborn Jesus Christ.
An El Niño is declared when sea temperatures in the tropical eastern Pacific rise 0.5°C above the long-term average. The conditions for declaring La Niña differ between different agencies, but during an event sea temperatures can often fall 3-5°C below average.
Professor Adam Scaife, head of long-range forecasting at the Met Office, told Channel 4’s FactCheck: “El Niño and La Niña, that cycle in the Pacific, are the biggest natural form of climate variability there is. It’s been going on for thousands of years, and every few years it flops one way and the next.”
How will El Niño affect the UK?
The last three winters have seen a run of three consecutive La Niña events, but forecasters are expecting a transition to El Niño in 2023. This could bring heatwaves and droughts in the summer, followed by a particularly cold winter.
The Met Office said: “The forecasts all indicate a sharp rise from the current neutral state to El Niño conditions by summer this year. While there is still considerable uncertainty in the magnitude of the event, some of these latest forecasts also suggest that a large El Niño event is possible, with sea surface temperatures in some forecasts reaching more than two degrees above normal by the autumn.”
Professor Scaife said: “The current record for global temperature occurred in 2016 and it’s no coincidence that followed the last big El Niño. If we get a big El Niño at the end of this year then, we’re likely to break the record for global temperature in 2024.”
What does El Niño mean for global warming?
El Niño-fuelled temperatures could worsen the climate change effects countries are already experiencing – including severe heatwaves, drought and wildfires.
The Met Office says: “Both historical observations and our physics-based computer models show that El Niño brings increased risk of drought to south-east Asia, India, north-eastern Australia and parts of the Amazon and southern Africa and increased risk of cold conditions to northern Europe in winter.
“We will be looking carefully at these regions with our colleagues at other national meteorological services as El Niño develops and updated forecasts become available.”
Experts have significant concerns if El Niño helps pushed global temperatures up past the 1.5ºC limit. Scientists in a special 2018 United Nations report said going past that point would be drastically and dangerously different with more death, destruction and damage to global ecosystems.
However, WMO secretary-general, Petteri Taalas, said what’s likely to happen in the next five years isn’t the same as failing the global goal.
“This report does not mean that we will permanently exceed the 1.5ºC level specified in the Paris Agreement which refers to long-term warming over many years. However, WMO is sounding the alarm that we will breach the 1.5ºC level on a temporary basis with increasing frequency,” he said.
The 66 per cent odds of a single year hitting that threshold in five years have increased from 48 per cent last year, 40 per cent the year before, 20 per cent in 2020 and 10 per cent about a decade ago. The WMO report is based on calculations by 11 different climate science centres across the globe.
There report said there is a 98 per cent chance of breaking the 2016 annual global temperature record between now and 2027, and a 98 per cent chance that the next five years will be the hottest five years on record.