External forcing explains recent decadal variability of the ocean carbon sink Journal Article uri icon

Overview

abstract

  • The ocean has absorbed the equivalent of 39% of industrial-age fossil; carbon emissions, significantly modulating the growth rate of; atmospheric CO2 and its associated impacts on climate. Despite the; importance of the ocean carbon sink to climate, our understanding of the; causes of its interannual-to-decadal variability remains limited. This; hinders our ability to attribute its past behavior and project its; future. A key period of interest is the 1990s, when the ocean carbon; sink did not grow as expected. Previous explanations of this behavior; have focused on variability internal to the ocean or associated with; coupled atmosphere/ocean modes. Here, we use an idealized upper ocean; box model to illustrate that two external forcings are sufficient to; explain the pattern and magnitude of sink variability since the; mid-1980s. First, the global-scale reduction in the decadal-average; ocean carbon sink in the 1990s is attributable to the slowed growth rate; of atmospheric pCO2. The acceleration of atmospheric pCO2 growth after; 2001 drove recovery of the sink. Second, the global sea surface; temperature response to the 1991 eruption of Mt Pinatubo explains the; timing of the global sink within the 1990s. These results are consistent; with previous experiments using ocean hindcast models with and without; forcing from variable atmospheric pCO2 and climate variability. The fact; that variability in the growth rate of atmospheric pCO2 directly; imprints on the ocean sink implies that there will be an immediate; reduction in ocean carbon uptake as atmospheric pCO2 responds to cuts in; anthropogenic emissions.

publication date

  • April 29, 2020

has restriction

  • closed

Date in CU Experts

  • November 14, 2020 7:27 AM

Full Author List

  • McKinley G; Fay A; Eddebbar Y; Gloege L; Lovenduski N

author count

  • 5

Other Profiles