60-Second Earth

135 Years of Records Reveals Deep Ocean Warming

The ocean surface is warming. Using records going back more than a century to the British Challenger expedition, researchers calculate that the deep ocean is experiencing its own temperature rise. David Biello reports

Her Majesty's Ship Challenger set sail in 1872. Stripped of her guns and outfitted for science, her mission was to sail around the globe sampling as she went.

Among other scientific triumphs, the Challenger gathered the first global set of ocean temperature readings, more than 260 in all. The British expedition measured from the surface to a depth beyond 900 meters.

In 2004 a set of drifting buoys began to make similar measurements. There are now more than 3,000 of these floats bobbing in the world's seas, collecting oceanographic information.

Comparing the data sets, separated by more than a century in time, reveals that, yes, the ocean is warming. On average, the global ocean is warmer by roughly 0.6 degrees Celsius at the surface and 0.1 degrees at depth. The analysis appears in the journal Nature Climate Change.

The extra heat trapped by the pollution from more than a century's worth of coal and other fossil fuel burning is beginning to reach the briny deep. That will have impacts from the survival of sea life to global rates of rainfall. Climate change dead ahead.

—David Biello

[The above text is a transcript of this podcast.]

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