Lauderdale, J. M., & Cael, B. B. (2021). Impact of Remineralization Profile Shape on the Air-Sea Carbon Balance. Geophysical Research Letters, 48 (7), e2020GL091746. https://doi.org/10.1029/2020GL091746
The ocean’s “biological pump” regulates atmospheric carbon dioxide levels and climate by transferring organic carbon produced at the surface by phytoplankton to the ocean interior via “marine snow,” where the organic carbon is consumed and respired by microbes. This surface to deep transport is usually described by a power-law relationship of sinking particle concentration with depth. Uncertainty in biological pump strength can be related to different variable values (“parametric” uncertainty) or the underlying equations (“structural” uncertainty) that describe organic matter export. This study evaluates structural uncertainty using an ocean biogeochemistry model by systematically substituting six alternative remineralization profiles fit to a reference power-law curve. Structural uncertainty makes a substantial contribution, about one-third in atmospheric pCO2 terms, to total uncertainty of the biological pump, highlighting the importance of improving biological pump characterization from observations and its mechanistic inclusion in climate models.