Super El Niño and Climate Change Drive Unseasonably Warm Autumn in UK

The United Kingdom is experiencing unseasonably warm weather as autumn begins, with temperatures forecast to reach 26°C (79°F) in London on Friday. Meteorologists cite a combination of a 'ridge' of high air pressure, the growing influence of a Super El Niño, and climate change as the primary drivers of this extended period of summer-like conditions.

The Super El Niño event, which is currently strengthening in the equatorial Pacific, has already broken temperature records months ahead of its expected peak. Record sea surface temperatures associated with this natural climate cycle, amplified by global warming, are contributing to warmer-than-average weather globally and in the UK.

According to Dr. Lucy Clarke of Nottingham Trent University, the El Niño event could lead to milder, wetter, and stormier weather later in autumn and into early winter. However, she noted that while El Niño has a strong grip on the Pacific and tropics, its direct impact on the UK's weather is less pronounced, with the Atlantic and the Jet Stream playing a more significant role in shaping the local climate.

Professor Nigel Arnell, a climate scientist at the University of Reading, explained that the current warm temperatures follow a pattern of consistently warm late winter, spring, and summer. He attributed this to three factors: the long-term trend of rising global temperatures due to climate change, higher-than-average sea surface temperatures in the Atlantic also linked to global warming, and the persistent position of the Jet Stream allowing warm air from the south to reach the UK.

The Met Office indicated that the warm weather began over the Atlantic, where a deep low-pressure system has been drawing warm air from Europe and subtropical Africa towards the UK. This weather pattern, combined with a ridge of high pressure over the UK, is creating settled conditions with sunny spells, leading to gradually increasing temperatures throughout the week.

Scientists emphasize that while weather patterns like El Niño cause natural variability, human-caused climate change has significantly altered the baseline temperatures. Professor Hannah Cloke, a meteorologist from the University of Reading, stated that when the weather pattern favors warmth, it now gets warmer than it used to due to the background warming trend. A recent Met Office study found that climate change made the record-breaking summer of this year 130 times more likely.

Professor Friederike Otto, a climate scientist at Imperial College London, echoed this sentiment, noting that every heatwave is made hotter and more probable by emissions from burning fossil fuels. The current Super El Niño is on track to be one of the largest in at least 1,000 years, with sea surface temperatures in the equatorial Pacific significantly above average.

While El Niño's most significant global temperature impact is expected into 2027, experts anticipate it will contribute to above-average global temperatures this autumn. Despite its global influence, scientists maintain that El Niño's direct effects on the UK's weather systems are limited, with the dominant drivers being Atlantic weather patterns and the Jet Stream. The prevailing warmth is largely attributed to climate change, with El Niño acting as an additional factor.