A sharp rise in global temperatures in 2023 set off a relentless series of disasters worldwide, from deadly wildfires in Los Angeles to severe flooding in Valencia. Scientists rushed to find the causes and concluded that a major warming of the Earth’s surface oceans played a key role. A new study from the University of Reading in the UK found that the upper layers of the oceans are now warming more than four times faster than they were in the late 1980s.
What did the researchers find? Led by meteorologist Chris Merchant, the team proposed several explanations for the excess heat beyond what El Niño and greenhouse gas emissions would predict. Their ideas included increased water vapor trapping heat after the 2022 eruption of the Hunga Tonga–Hunga Ha’apai volcano; a drop in cooling aerosols following changes in shipping regulations; and unusually strong activity in the current solar cycle. Even taken together, however, those factors could not fully explain the observed temperature spike, Science Alert reported.
To dig deeper, the researchers used satellite records dating back to 1985 to track how ocean surface temperatures have changed. They found that about 40 years ago the rate of warming was roughly 0.06 °C, while it is now about 0.27 °C. That’s not a steady, linear change — it’s accelerating. While part of the recent excess heat is attributable to the El Niño event, the team estimates that 44 percent of the acceleration in ocean warming comes from the oceans absorbing heat much faster than predicted over the last decade. “If you imagine the oceans as a bathtub, in the 1980s the hot tap was running slowly, warming the water by just a fraction of a degree each decade. But now the hot tap is running much faster, and the warming is picking up speed,” Merchant said.
Why is that alarming? The researchers warn that if the trend continues, ocean temperatures over the next 20 years could exceed the rise seen in the past 40 years. Meanwhile, global warming is already damaging wildlife, causing crop failures that leave millions without food, and harming people’s health around the world.
Merchant’s team says policymakers and the public need to understand that this pace of warming raises the risk of rapid, irreversible changes in the coming decades. “This underscores the urgency of radically reducing fossil fuel consumption,” the report states. The researchers add that every action to cut greenhouse gas emissions can save lives in the future. The study appears in the journal Environmental Research Letters.
