Interesting article recently released, which indicates that the North Atlantic is less able to uptake carbon dioxide than it was thirty years ago. Researchers were able to weed out the long-term trends from (often conflicting) short-term natural variability by combining multiple datasets.
During the past three decades, increases in atmospheric carbon dioxide have largely been matched by corresponding increases in dissolved carbon dioxide in the seawater. The gases equilibrate across the air-water interface, influenced by how much carbon is in the atmosphere and the ocean and how much carbon dioxide the water is able to hold as determined by its water chemistry.
But the researchers found that rising temperatures are slowing the carbon absorption across a large portion of the subtropical North Atlantic. Warmer water cannot hold as much carbon dioxide, so the ocean’s carbon capacity is decreasing as it warms.
If this trend is occurring in oceans globally, that would indicate the world is filling up one of its largest carbon sinks, and doing so at an increasing rate as time goes by. Losing the ocean’s ability to absorb almost one third of global carbon emissions would have dire consequences for any climate change mitigation efforts in motion now and in the future. We’re having a tough enough time curbing emissions to a rate that would stabilize atmospheric CO2 at 450ppm (let alone the 350 ppm levels researchers currently recommend). Shrinking the buffer that ocean sinks provide could really swamp the system.