Forced variability in the ocean carbon sink, 1980 to present
Abstract
The ocean significantly modulates atmospheric CO2, having absorbed the equivalent of 41% of industrial-age fossil carbon emissions. On millennial timescales, the ocean will absorb approximately 85% of anthropogenic emissions. Despite this critical role for the ocean in regulating climate, we lack a detailed understanding of the mechanisms of variability in the ocean carbon sink. Here, I study the externally forced component of surface ocean pCO2 and air-sea CO2 fluxes using two climate model large ensembles and a simple box model. Forced change in surface ocean pCO2 is strongly driven by the variable atmospheric pCO2 growth rate and by large volcanic eruptions. The slowdown of emissions with the breakup of Soviet Union combined with the 1992 Mt. Pinatubo eruption led to significant forced anomalies in pCO2 in the 1990s that are apparent in surface ocean pCO2 data. Since CO2 fluxes act to restore the ocean toward the atmosphere, the signal of the atmospheric pCO2 growth rate is damped in the CO2 flux forced trend while the impact of volcanos remains clear. Removing the externally forced component from the total variability should allow for clearer assessment of the impacts of internal variability on the ocean carbon sink.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFM.B51E1998M
- Keywords:
-
- 3309 Climatology;
- ATMOSPHERIC PROCESSESDE: 0428 Carbon cycling;
- BIOGEOSCIENCESDE: 4273 Physical and biogeochemical interactions;
- OCEANOGRAPHY: GENERAL