Ocean Thermostats

September 23, 2006
By Damond Benningfield

In some science fiction movies, the oceans can freeze in mid-wave, saving the heroes for another day. But such a quick-freeze is possible only in the imagination of a writer.

Sea surface temperatures around the globe. Photo: National Oceanic & Atmospheric Administration/National Climatic Data Center

In real life, the oceans are quite efficient at storing heat. They distribute this heat around the globe, helping to keep the temperatures fairly moderate all year ’round.
The oceans cover more than 70 percent of Earth’s surface. As it absorbs energy from the Sun, the water gets warmer. At night, though, but it doesn’t radiate its heat back into space as quickly as the land does. That’s because water has a high heat capacity.

The wind drives the currents in the top layers of the oceans, pushing water around the globe. As the water moves into colder regions, it releases more of its heat, warming those parts of the planet. Without the oceans to distribute heat, the seasonal temperature changes would be much more extreme.

In the northern hemisphere, for example, the region between the equator and 30 degrees north - about the northern edge of the Gulf of Mexico - takes in more heat from the Sun than it releases. But the region farther north loses more heat than it receives. The Gulf Stream Current carries the Gulfs extra heat northward, maintaining an essentially constant temperature in the North Atlantic.

Understanding how the oceans distribute heat, and how they interact with the atmosphere, is crucial for improving our ability to predict changes in the world’s climate.

copyright: Damond Benningfield