Unprecedented Marine Heatwave Wreaks Havoc in the North Pacific

Sun Oct 19 2025 16:05:12 GMT+0300 (Eastern European Summer Time)

A mysterious marine heatwave has led to record-high temperatures in the North Pacific, raising alarms about its potential impacts on global weather patterns, including colder conditions in the UK this winter.

The North Pacific Ocean has registered its warmest summer on record, with temperatures surpassing the previous high by over 0.25°C. This phenomenon, linked to climate change and unique atmospheric conditions, has implications for weather patterns across the globe, including the possibility of colder winters in the UK due to altered jet streams. Researchers are investigating multiple factors contributing to this unusual warming, including changes in shipping fuels and natural variability.

The waters of the north Pacific have had their warmest summer on record, according to BBC analysis of a mysterious marine heatwave that has confounded climate scientists.

Sea surface temperatures between July and September were more than 0.25C above the previous high of 2022 - a significant increase across an area roughly ten times the size of the Mediterranean.

While climate change is known to make marine heatwaves more likely, scientists are struggling to explain why the north Pacific has been so hot for so long.

Yet, this excess heat in the so-called warm blob may have the opposite effect in the UK, possibly leading to a colder start to winter, some researchers believe.

There's definitely something unusual going on in the north Pacific, said Zeke Hausfather, a climate scientist at Berkeley Earth. Such a jump in temperatures across a region so large is quite remarkable.

The BBC analyzed data from the European Copernicus climate service to calculate average temperatures between July and September across a large area of the north Pacific, sometimes known as the warm blob. This region extends from the east coast of Asia to the west coast of North America, the same area used in previous scientific studies.

The figures show that not only has the region been warming quickly over the past couple of decades, but 2025 is markedly higher than recent years too.

That the seas are getting hotter is no surprise. Global warming, caused by humanity's emissions of carbon dioxide and other gases, has already trebled the number of days of extreme heat in oceans globally. However, the observed temperatures have been even higher than climate models predicted.

Natural weather variability, including weaker-than-usual winds this summer, is believed to play a part in retaining these warm temperatures at the sea surface. However, researchers emphasize that natural variability is not the sole reason behind this extraordinary situation.

One hypothesis posits that a change in shipping fuels might favor the warming. Before 2020, dirty engine oil produced large amounts of sulfur dioxide, which while harmful, created aerosols that reflected sunlight, aiding in regulating ocean temperatures. The removal of this cooling effect could be revealing the acute impacts of warming caused by human activity.

The warm water in the north Pacific has already influenced weather patterns significantly, leading to intense heatwaves in regions like Japan and South Korea and generating powerful storms in the US.

In California, extremely warm ocean waters have contributed to enhanced thunderstorms, providing heat and moisture that can worsen rainfall and flooding events.

As the winter months approach, the overall implications for Europe are profound. The warm conditions in the North Pacific could create atmospheric waves that influence weather patterns, potentially leading to colder conditions as they interact with broader atmospheric systems.

Additionally, a weak La Niña phenomenon occurring in the eastern tropical Pacific might further complicate predictions, as La Niña typically leads to colder winters in the UK, although it can also bring milder conditions later in the season.

Future monitoring and analysis will be vital in understanding the implications of these developments for both local weather patterns and global climate dynamics as we head into winter.