The world's oceans, which normally gobble up carbon dioxide, are getting stuffed to the gills, according to the most thorough study to date of human-made carbon in the seas.
Between 2000 and 2007, as emissions of the potent greenhouse gas carbon dioxide skyrocketed, the amount of human-made carbon absorbed by the oceans fell from 27 to 24 percent.
In terms of ocean processes, "that's a pretty large drop, and the trend is pretty clear: The ocean can't keep up with [human-made carbon]," said study leader Samar Khatiwala, an oceanographer at Columbia University's Lamont-Doherty Earth Observatory.
Khatiwala is careful to point out that the total uptake of carbon is not declining—the rate is just not growing as fast as it used to.
But if the oceans continue to be overwhelmed by carbon, more of the gas will remain in the already warming atmosphere, the authors say.
"Ultimately the ocean is what's controlling what's going on here," said Chris Sabine, a supervisory oceanographer at NOAA's Pacific Marine Environmental Laboratory in Seattle, Washington, who was not involved in the research.
"It's a big deal that it's becoming less efficient in taking up CO2."
It's hitting a wall. Considering that emissions went up in that time frame - this past year up 2% despite the economic slow down and driven by China, not the US - the drop is less than they imply, but still there.
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