 | OCEANIC SOURCES AND SINKS FOR ATMOSPHERIC CO2 |
 by N. Gruber
Owing to the combination of greatly improved observational constraints
and new data analysis and modeling techniques, our ability to constrain the
role of the ocean in the global carbon cycle has made great advances in the
past decade. By combining ocean interior carbon data with ocean general
circulation models in an inverse manner, we can constrain the oceanic uptake of
anthropogenic CO2 to within an unprecedented narrow range of
2.20±0.25 Pg C yr-1 for a nominal year of 1995. The inversely
estimated pre-industrial air-sea fluxes reveal the expected pattern with CO2
outgassing in the tropics and CO2 uptake at mid to high latitudes.
The subpolar regions of the Southern Hemisphere defy this trend, exhibiting
strong outgassing of natural CO2. This outgassing nearly cancels the
large uptake of anthropogenic CO2 in this region, leading to a near
zero net contemporary flux. The contemporary air-sea fluxes from the inversion
agree reasonably well with flux estimates derived from ∆pCO2
observations, with the exception of the above subpolar regions, where our flux
estimates are three to five times smaller. When analyzed together with the
observed atmospheric CO2 gradients, our results support the
existence of a substantial sink for atmospheric CO2 in the northern
hemisphere terrestrial biosphere, and a terrestrial carbon loss in the tropics.
Link to Abstract
Link to Slides
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