evidence: The concentration of carbon dioxide (CO2) in ocean water (y axis) depends on the amount of CO2 in the atmosphere (shaded curves) and the temperature of the water (x axis). This simplified graph shows that as atmospheric CO2 increases from pre-industrial levels (blue) to double (2X) the pre-industrial amounts (light green), the ocean CO2 concentration increases as well. However, as water temperature increases, its ability dissolve CO2 decreases. Global warming is expected to reduce the ocean’s ability to absorb CO2, leaving more in the atmosphere…which will lead to even higher temperatures. (Graph by Robert Simmon.) [...] When Le Quéré plugged atmospheric measurements from the Southern Ocean between 1981 and 2004 into her model, she was startled by the result—something far more interesting than the Antarctic Circumpolar Wave. "The Southern Ocean carbon sink has not changed at all in 25 years. That’s unexpected because carbon dioxide is increasing so fast in the atmosphere that you would expect the sink to increase as well," says Le Quéré. But it hadn’t. Instead, the Southern Ocean held steady, while atmospheric carbon dioxide concentrations climbed. Why?