When it comes to slowing down global warming, the world’s oceans—70 percent of the planet’s surface—may be Homo sapiens’ best hope for a stable future. In July researchers from the National Oceanic and Atmospheric Administration published findings that the oceans store almost half the anthropogenic carbon dioxide—the CO2 produced by humans—released into the atmosphere. “We’ve known for a number of years that the oceans take up a lot of CO2,” says Christopher Sabine, a chemical oceanographer with the NOAA office in Seattle. “But up to now, that’s been from indirect estimates or models. This is the first time we’ve been able to quantify it from direct measurements in the oceans.”
And measure they did. Throughout the 1990s, international teams of scientists on research vessels traversed the oceans east to west and north to south, stopping every 30 miles to lower instruments overboard. At each stop, they collected water from 36 different depths—72,000 measurements from 9,600 locations around the globe.
Sabine says the oceans are “performing this tremendous service for humankind.” But that support is not without cost and danger. The oceans now have far higher concentrations of CO2, as well as the lowest pH in millions of years. The changes, warns Sabine, “may have serious effects on the organisms that live in the ocean—in ways we don’t yet understand.”