Leeds professor on what to expect from "unprecedented” El Niño as it breaks records weeks before expected peak
John Marsham, Professor of Atmospheric Science at the University of Leeds, explains the El Niño and how the record-breaking phenomenon could impact the UK.
A University of Leeds professor says “the weakest [El Niño] forecast is still going to be extremely strong”, as the climate phenomenon breaks record weeks before its expected peak.
Daily sea surface temperatures in a key part of the Pacific were 3.05°C above average on 19 September, higher than the 3.02°C record set in November 2015.
John Marsham, Professor of Atmospheric Science, at the University of Leeds explains that anything over a 2°C rise is considered strong and the ocean temperatures currently being seen are “off the charts”.
El Niño explained
Defining the El Niño, Marsham says: “El Niño is a natural variability in Earth's climate, based around the Pacific Ocean.
“Normally, the warm water is towards the west of the Pacific Ocean and every few years that changes so that the winds blow the warm water towards the west on the equator and then those warm waters shift towards the east and that's what we call El Niño.
“How much evaporation and heating of air over the sea you get depends on how warm the oceans are, so that change in where the warm water is in the Pacific Ocean then affects where rainfall happens and where droughts happen.
“That's all in the Pacific, but that rainfall is releasing lots of energy and heat into our atmosphere and that then affects the weather all around the world.”
El Niño and climate change
The El Niño formula is natural, roughly occurring every two to seven years, but Marsham says the burning of fossil fuels makes the impacts of the phenomenon stronger.
He says: “Burning of fossil fuels has increased the temperature of the air, it's increased the temperature of the oceans. Warm air can hold more water so you get heavier rainfall and warm air increases evaporation so for the same lack of rainfall you get more evaporation from the soil, so it makes droughts worse.”
El Niño’s impact on the UK weather
With El Niño based in the tropical Pacific, its strongest impacts are in the tropical regions. The impact the El Niño could have on weather in the UK is weaker and less certain.
Marsham says: “Later this year, October to December, we expect stronger westerly winds, where many of our storms come from, so stronger winds and storms, and then January, February more chance of cold snaps. Both of those things are quite uncertain.”
Marsham highlights how the impacts of the recent drought could combine with the El Niño. Trees weakened by record low rainfall and high temperatures could get hit by very high winds.
How El Niño could disrupt food production and energy systems
The El Niño is expected to impact global food systems and UK food supply chains.
The UN World Food Programme (WFP) has said 49 million more people in highly vulnerable communities globally are set to be pushed into acute hunger because of the El Niño.
Supply of affected commodities to the UK will likely continue, but reduced global yields are predicted to result in higher prices.
Key risks
Rice, multiple key producers, like India, Thailand and Vietnam are expected to face weather impacts from El Niño.
Wheat and grains - droughts in Australia and the USA could lead to reduced exports, however, some data suggests that historically El Niño can result in a slight drop in global wheat prices.
Tropical commodities like coffee and cocoa are particularly vulnerable.
Government research says some have estimated El Niño could cause food prices to double in the UK, but the data is limited and confidence in this is low. The last El Niño, in 2023, had virtually no discernible impact on UK food prices.
Marsham says: “It looks like it [El Niño] will push up energy prices by pushing up demand for natural gas.
“The Panama Canal is already short of water. It could increase the water stress in the Panama Canal that means that fewer ships can go through. So that then has further economic impacts and pushing up energy prices again affects food prices.”
Demand would likely increase with more pronounced hot or cold weather and cause already high energy prices to rise.
Marsham says: “The weakest forecast it’s still going to be extremely strong. The scale of the impacts are quite uncertain because we haven’t experienced this before and this is what we need to prepare for.
“People think of extreme weather in terms of the weather they have experienced before or in living memory, but we have to prepare for absolutely unprecedented events. That includes not only unprecedented weather in the UK, but unprecedented disruption to UK food supplies because we are by necessity dependent on other regions for our food.
“This is only going to get worse until we stop burning fossil fuels. It won’t get better at that point, we will have to live with the climate that we have, but it’s going to carry on getting worse until we phase out fossil fuels.”