When a whale dies, it sinks to the bottom of the ocean. As it decomposes, much of the carbon that makes up its body stays on the sea floor. The same thing happens when other ocean creatures die, creating a carbon-rich sediment that builds over millennia.

“We know that the sea floor is the largest carbon storehouse on the planet,” says Enric Sala, a marine ecologist and an explorer-in-residence at the National Geographic Society.

He says that globally, the sediment on the ocean floor stores more carbon than all the soil on Earth.

“But we are disturbing some of that sediment and that carbon because of bottom trawling, which is a destructive fishing practice that plows the sea floor with large and heavy nets,” he says.

Stirring up the sediment can release some of that long-stored carbon, some of which turns into carbon dioxide.

Scientists are working to determine how much of that CO₂ escapes to the atmosphere and warms the climate.

Having more CO₂ in the water also makes it more acidic, which can harm ocean creatures.

So to keep more carbon locked away in ocean sediment, Sala says it’s important to protect large areas of the ocean from destructive fishing methods.

Reporting credit: Sarah Kennedy/ChavoBart Digital Media