The rate at which the oceans are warming has surged dramatically over the past four decades, a new study has revealed. According to the research, ocean temperatures were rising at a rate of approximately 0.06 degrees Celsius per decade in the late 1980s. However, by the early 2020s, this rate had more than quadrupled, reaching 0.27 degrees Celsius per decade. This trend highlights an alarming acceleration in ocean warming, and the study offers critical insights into why 2023 and early 2024 saw some of the highest ocean temperatures ever recorded.
The Study and Its Findings
Published on January 28, 2025, in Environmental Research Letters, the study provides a detailed analysis of the rapid increase in ocean warming over recent decades. The research was led by Professor Chris Merchant from the University of Reading, who explains that the findings are vital in understanding the broader context of global climate change.
Professor Merchant likened the ocean’s warming process to a bathtub, with the “hot tap” representing the influx of heat into the oceans. He described the situation in the 1980s as if the hot tap was running slowly, warming the water by just a fraction of a degree per decade. However, the pace of warming has dramatically increased in recent years, as the “hot tap” now runs much faster, contributing to a much more rapid rise in ocean temperatures.
The study’s findings underscore the urgency of addressing climate change through global efforts to reduce carbon emissions and transition toward net-zero carbon emissions. By doing so, we could “close off the hot tap” and slow down the rate of ocean warming.
The Role of Earth’s Energy Imbalance
The accelerating ocean warming is driven by an expanding energy imbalance in the Earth’s climate system. This imbalance occurs when more energy from the sun is absorbed by the planet than is radiated back into space. Over the past several decades, this energy imbalance has roughly doubled since 2010, largely due to increasing levels of greenhouse gases in the atmosphere. These gases trap heat, preventing it from escaping into space and effectively increasing the Earth’s overall temperature.
Moreover, the Earth is now reflecting less sunlight back into space compared to previous decades, contributing further to the energy imbalance and, by extension, to the rising temperatures of the planet, including its oceans.
Record-High Ocean Temperatures
In 2023 and early 2024, global ocean temperatures hit record highs, with the oceans experiencing 450 consecutive days of above-average temperatures. While some of this warming can be attributed to El Niño, a periodic natural warming event in the Pacific Ocean, scientists have determined that the majority of the record temperatures result from a much faster rate of ocean warming over the past decade compared to earlier periods.
A comparison with the 2015–2016 El Niño, another significant natural event, showed that the ocean surface warming in the past 10 years has been significantly higher. In fact, 44% of the unprecedented ocean warmth observed in 2023 and early 2024 can be attributed to the oceans absorbing heat at an accelerating rate, as opposed to just natural variability like El Niño.
What Does This Mean for the Future?
The study’s findings have important implications for the future trajectory of global ocean temperatures and climate change. While the ocean warming trends of the past few decades provide a useful historical context, they are not an accurate predictor of what to expect in the coming decades. In fact, it is highly plausible that the rate of ocean warming observed in the last 40 years will be surpassed in just the next 20 years if current trends continue.
This has significant consequences for the global climate. As the oceans warm, they release heat into the atmosphere, contributing to global temperature increases. The warming of the oceans also exacerbates the melting of polar ice, sea level rise, and extreme weather patterns.
Since the surface oceans play a crucial role in driving global climate patterns, the acceleration in their warming emphasizes the urgency of reducing fossil fuel consumption. By curbing greenhouse gas emissions and mitigating the effects of climate change, it may still be possible to prevent even more rapid temperature increases in the coming decades and stabilize the global climate.
The Importance of Immediate Action
The study highlights that ocean warming is not merely a concern for coastal regions but is a fundamental factor driving the broader climate crisis. As ocean temperatures continue to rise, the global climate will experience increasingly severe changes, including more extreme heatwaves, stronger storms, and rising sea levels. This, in turn, could have devastating effects on ecosystems, human populations, and economies, particularly in coastal areas.
To slow down the rate of ocean warming and mitigate the impacts of climate change, it is crucial to take immediate action. This includes reducing greenhouse gas emissions, transitioning to renewable energy sources, and enhancing global cooperation to tackle climate change. Without such efforts, the accelerating rate of ocean warming could push the Earth into even more dangerous levels of global temperature rise, with dire consequences for the planet’s future.
In conclusion, the findings of this study serve as a stark reminder of the rapid and ongoing changes happening in the Earth’s climate system. The accelerating rate of ocean warming over the past four decades provides clear evidence of the urgent need for global action to combat climate change and reduce the warming of our planet. The health of the oceans and the stability of the global climate are intrinsically linked, and the actions we take today will determine the trajectory of our planet’s future.
Reference: Quantifying the acceleration of multidecadal global sea surface warming driven by Earth’s energy imbalance, Environmental Research Letters (2025). DOI: 10.1088/1748-9326/adaa8a