The waters of the North Pacific have experienced their warmest summer on record, with an enigmatic marine heatwave baffling climate scientists. Temperatures across a vast expanse of the ocean, roughly ten times the size of the Mediterranean, surged by over 0.25C above the previous record set in 2022 during July, August, and September.
While climate change is a known contributor to more frequent marine heatwaves, the sheer scale and persistence of this ‘warm blob’ are proving difficult to explain. Researchers are investigating various factors, including potential impacts from recent changes in shipping fuel regulations that may have reduced atmospheric cooling aerosols, and shifts in air pollution in East Asian cities.
These warmer Pacific waters are already influencing weather patterns on both sides of the ocean. In East Asia, exceptionally high summer temperatures were recorded, while in North America, increased moisture from the Pacific is thought to have fueled more intense storms and atmospheric rivers, leading to heavy rainfall and potential flooding.
The unusual heatwave could also have knock-on effects for weather systems reaching Europe and the UK. Some scientists suggest that the heat in the North Pacific might contribute to atmospheric patterns favouring colder Arctic air being drawn into Europe, potentially leading to a cooler start to the upcoming winter. However, this remains an area of active research, as the complex interplay of global weather systems means predicting winter conditions is always challenging, especially with the ongoing trend of milder winters due to climate change.
Adding another layer of complexity is the emergence of La Niña conditions in the eastern tropical Pacific, typically associated with cooler ocean temperatures. While La Niña can influence UK winter weather, favouring a colder start but potentially a milder end, its interaction with the dominant North Pacific heatwave is a key focus for forecasters. Scientists are closely observing how these competing phenomena will shape the weather in the months ahead.
More weekend picks
Intense Med Sea heatwave raises fears for marine life
The before and after images showing glaciers vanishing before our eyes
Tiny creatures gorge, get fat, and help fight global warming