An assessment of the Atlantic and Arctic sea–air CO2 fluxes, 1990–2009

[摘要] TheAtlantic and Arctic Oceans are critical components of the global carboncycle. Here we quantify the net sea–air CO₂ flux, for the first time,across different methodologies for consistent time and space scales for theAtlantic and Arctic basins. We present the long-term mean, seasonal cycle,interannual variability and trends in sea–air CO₂ flux for the period1990 to 2009, and assign an uncertainty to each. We use regional cuts fromglobal observations and modeling products, specifically a pCO₂-basedCO₂ flux climatology, flux estimates from the inversion of oceanic andatmospheric data, and results from six ocean biogeochemical models.Additionally, we use basin-wide flux estimates from surface ocean pCO₂observations based on two distinct methodologies. Our estimate of thecontemporary sea–air flux of CO₂ (sum of anthropogenic and naturalcomponents) by the Atlantic between 40° S and 79° N is−0.49 ± 0.05 Pg C yr⁻¹,and by the Arctic it is −0.12 ± 0.06 Pg C yr⁻¹, leading to a combined sea–air flux of −0.61 ± 0.06 Pg C yr⁻¹for the two decades (negative reflects oceanuptake). We do find broad agreement amongst methodologies with respect tothe seasonal cycle in the subtropics of both hemispheres, but not elsewhere.Agreement with respect to detailed signals of interannual variability ispoor, and correlations to the North Atlantic Oscillation are weaker in theNorth Atlantic and Arctic than in the equatorial region and southernsubtropics. Linear trends for 1995 to 2009 indicate increased uptake andgenerally correspond between methodologies in the North Atlantic, but thereis disagreement amongst methodologies in the equatorial region and southernsubtropics.

[学科分类] 地球化学与岩石