Hotter oceans threaten everyone on land

The Earth's oceans are heating up, and that is a problem for all of us. Fortunately, it is a problem we can fix.

I work with a team of scientists who study the Earth's temperature. Our research shows that the oceans are gradually warming, and this warming has consequences for our societies.

Why are we studying the oceans? It is because the oceans are very large. They cover 70 percent of the planet. They are also very deep, on average thousands of meters, and therefore have a tremendous mass. This also means that ocean temperatures change slowly over time, making them an excellent way to measure long-term climate change. An important feature of the oceans is that they absorb approximately 90 percent of the extra heat from global warming. Therefore, if you want to measure how fast the Earth is warming, the answer is in the oceans.

Oceans are also important because they greatly affect weather patterns. As air passes over the ocean, it picks up heat and moisture — the two ingredients that drive weather. So, as our oceans warm, the atmosphere warms and becomes more humid — leading to more extreme weather.

This is a warning that the planet's weather is becoming more extreme. Rainfalls that used to be 10 cm are now 14 cm. Storms that used to have wind speeds of 100 km per hour are now blowing at 120 km per hour. Typhoons that used to be 500 km in diameter are now 750 km. Droughts that used to last one week now persist for longer durations. This is how climate change and warming oceans "supercharge" our weather, and we pay the consequences. In 2025, several extreme weather events caused damage and loss of life, including widespread flooding in Asia, drought in the Middle East, and heavy rain in Mexico and the Pacific Northwest.

My team has been studying ocean temperatures for nearly a decade, and our data clearly show that the oceans are warming. Other researchers have come to similar conclusions. With high-quality data extending back to the 1950s, we have a clear picture of long-term climate change. We are observing what scientists predicted many years ago — man-made increases in greenhouse gases lead to warming.

While we are not surprised by the warming trend, the patterns are definitely intriguing. It turns out the oceans do not warm uniformly. Some areas are warming faster than others. Last year, the Atlantic, Mediterranean, Northern Pacific, and Southern Ocean warmed more than the rest of the world. Part of this is explained by wind patterns in the atmosphere. Other patterns are explained by the well-known El Ni?o/La Ni?a process, a naturally occurring pattern in the Pacific Ocean that creates localized warming and cooling patterns every few years. Another contributing factor is vertical motion in the ocean. Warm waters near the surface descend to the ocean depths in a process called "downwelling". In other areas, "upwelling" brings deep cold waters to the surface. Both downwelling and upwelling are natural processes, but climate change may be changing how strong these currents are.

Regardless of the cause, these warming patterns are being studied by the world's top climate scientists for additional clues to climate change.

While there is plenty of worrisome news, there is also a reason to be optimistic. Recent decreases in the cost of green energy have made wind and solar power less expensive than coal. The expansion of electric vehicles driven by sunlight directly reduces emissions from automobile tailpipes. Improvements to energy efficiency mean we can get more work done with less fuel. While I share my colleagues' optimism that we can change the trajectory of our planet, we need to act quickly. Every day we delay action will make the future more challenging. But if we make smart choices, we can generate the energy to power our cities, homes, workplaces, and communities. By using renewable energy, we can provide this power more cheaply and without harming the environment. It is a "win-win" situation; who can be against that?

The author is a professor of thermal sciences at the School of Engineering of the University of St. Thomas, United States.

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