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- Title
Global ocean carbon uptake: magnitude, variability and trends.
- Authors
Wanninkhof, R.; Park, G.-H.; Takahashi, T.; Sweeney, C.; Feely, R.; Nojiri, Y.; Gruber, N.; Doney, S. C.; McKinley, G. A.; Lenton, A.; Le Quéré, C.; Heinze, C.; Schwinger, J.; Graven, H.; Khatiwala, S.
- Abstract
Estimates of the anthropogenic global-integrated sea-air carbon dioxide (CO2) flux from 1990 to 2009, based on different models and measurements, range from -1.4 to -2.6 PgCyr-1 . The median values of anthropogenic CO2 for each method show better agreement and are: -1.9 for PgCyr-1 for numerical ocean general circulation hind cast models (OGCMs) with parameterized biogeochemistry; -2.1 PgCyr-1 for atmospheric inverse models; -1.9 PgCyr-1 for global atmospheric constraints based on O2 /N2 ratios for 1990-2000; and -2.4 PgCyr-1 for oceanic inverse models. An updated estimate of this anthropogenic CO2 flux based on a climatology of sea-air partial pressure of CO2 differences (ΔpCO2) (Takahashi et al., 2009) and a bulk formulation of gas transfer with wind speed for year 2000 is -2.0 PgCyr-1 . Using this ΔpCO2 climatology and empirical relationships of pCO2 with sea-surface temperature (SST) anomalies (Park et al., 2010a), the interannual variability of the contemporary CO2 flux is estimated to be 0.20 PgCyr-1 (1σ) from 1990 through 2009. This is similar to the variability estimated by the OGCMs of 0.16 PgCyr-1 but smaller than the interannual variability from atmospheric inverse estimates of 0.40 PgCyr-1. The variability is largely driven by large-scale climate re-organizations. The decadal trends for different methods range from -0.13 (PgCyr-1) decade-1 to -0.50 (PgCyr-1) decade-1. The OGCMs and the data based sea-air CO2 flux estimates show smaller uptakes and appreciably smaller decadal trends than estimates based on changes in carbon inventory suggesting that methods capable of resolving shorter timescales are showing a slowing of the rate of ocean CO2 uptake. It is not clear if this large difference in trend is a methodological issue or a real natural feedback.
- Subjects
CARBON dioxide in seawater; ESTIMATES; OCEAN-atmosphere interaction; OCEAN circulation; BIOGEOCHEMISTRY; GENERAL circulation model; CLIMATOLOGY
- Publication
Biogeosciences Discussions, 2012, Vol 9, Issue 8, p10961
- ISSN
1810-6277
- Publication type
Article
- DOI
10.5194/bgd-9-10961-2012