ETH Zurich environmental physics professor Nicolas Gruber and his team have determined the ocean sink from 1994 to 2007. Their findings published in the Science showed that the ocean has accumulated 34 gigatonnes of anthropogenic carbon dioxide in 13 years.
Mechanism of carbon dioxide absorption
Fossil fuels generate carbon dioxide during combustion. This is absorbed not only in the atmosphere but also in the ocean and the land ecosystems.
The ocean dissolves carbon dioxide in the surface water and is distributed into the ocean currents. The dissolved carbon dioxide is transported through the mixing processes from the surface deep into the interior of the ocean.
The oceanic sink for carbon dioxide is largely dependent on this overturning circulation. The absence of this sink would be detrimental as it would increase the carbon dioxide amount in the atmosphere.
There is a relatively stable amount of carbon dioxide absorbed in the oceans in comparison to the last 200 years. The concern is that as atmospheric carbon dioxide concentration increases, there is also an increase in the oceanic sink. There will come a time, however, that the ocean will become saturated.
So far, that point has not been reached. "Over the examined period, the global ocean continued to take up anthropogenic CO2at a rate that is congruent with the increase of atmospheric CO2," Gruber explains.
Numerous model-based estimates of the ocean sink for human-made carbon dioxide confirm the findings of their research. "This is an important insight, giving us confidence that our approaches have been correct," Gruber adds.
