Assessment of the sea-ice carbon pump: Insights from a three-dimensional ocean-sea-ice biogeochemical model (NEMO-LIM-PISCES)
|Author(s)||Moreau Sebastien1, 2, Vancoppenolle Martin3, Bopp Laurent4, Aumont Olivier5, Madec Gurvan3, 6, Delille Bruno7, Tison Jean-Louis8, Barriat Pierre-Yves1, Goosse Hugues1|
|Affiliation(s)||1 : Catholic Univ Louvain, Earth & Life Inst, Georges Lemaitre Ctr Earth & Climate Res, Louvain La Neuve, Belgium.
2 : Univ Tasmania, Inst Marine & Antarctic Studies, Hobart, Tas, Australia.
3 : UPMC Paris 6, Sorbonne Univ, LOCEAN IPSL, CNRS, Paris, France.
4 : CNRS, Inst Pierre Simon Laplace, Lab Sci Climat & Environm, Gif Sur Yvette, France.
5 : Inst Rech Dev, Lab Phys Oceans, Brest, France.
6 : Natl Oceanog Ctr, Southampton, Hants, England.
7 : Univ Liege, MARE, Unite Oceanog Chim, Liege, Belgium.
8 : Univ Libre Bruxelles, Fac Sci, Lab Glaciol, Brussels, Belgium.
|Source||Elementa-science Of The Anthropocene (2325-1026) (Univ California Press), 2016-08 , Vol. 4 , N. 000122. , P. 14p.-|
|WOS© Times Cited||16|
The role of sea ice in the carbon cycle is minimally represented in current Earth System Models (ESMs). Among potentially important flaws, mentioned by several authors and generally overlooked during ESM design, is the link between sea-ice growth and melt and oceanic dissolved inorganic carbon (DIC) and total alkalinity (TA). Here we investigate whether this link is indeed an important feature of the marine carbon cycle misrepresented in ESMs. We use an ocean general circulation model (NEMO-LIM-PISCES) with sea-ice and marine carbon cycle components, forced by atmospheric reanalyses, adding a first-order representation of DIC and TA storage and release in/from sea ice. Our results suggest that DIC rejection during sea-ice growth releases several hundred Tg C yr(-1) to the surface ocean, of which < 2% is exported to depth, leading to a notable but weak redistribution of DIC towards deep polar basins. Active carbon processes (mainly CaCO3 precipitation but also ice-atmosphere CO2 fluxes and net community production) increasing the TA/DIC ratio in sea-ice modified ocean-atmosphere CO2 fluxes by a few Tg C yr(-1) in the sea-ice zone, with specific hemispheric effects: DIC content of the Arctic basin decreased but DIC content of the Southern Ocean increased. For the global ocean, DIC content increased by 4 Tg C yr(-1) or 2 Pg C after 500 years of model run. The simulated numbers are generally small compared to the present-day global ocean annual CO2 sink (2.6 +/- 0.5 Pg C yr(-1)). However, sea-ice carbon processes seem important at regional scales as they act significantly on DIC redistribution within and outside polar basins. The efficiency of carbon export to depth depends on the representation of surface-subsurface exchanges and their relationship with sea ice, and could differ substantially if a higher resolution or different ocean model were used.