Biological and Environmental Research - Earth and Environmental System Sciences
Earth and Environmental System Modeling

A Joint Role for Forced and Internally-Driven Variability in the Decadal Modulation of Global Warming

TitleA Joint Role for Forced and Internally-Driven Variability in the Decadal Modulation of Global Warming
Publication TypeJournal Article
Year of Publication2020
AuthorsLiguori, Giovanni, McGregor Shayne, Arblaster Julie M., Singh Martin S., and Meehl Gerald A.
JournalNature Communications
Volume11
Number1
Abstract / Summary

Despite the observed monotonic increase in greenhouse-gas concentrations, global mean temperature displays important decadal fluctuations typically attributed to both external forcing and internal variability. Here, we provide a robust quantification of the relative contributions of anthropogenic, natural, and internally-driven decadal variability of global mean sea surface temperature (GMSST) by using a unique dataset consisting of 30-member large initial-condition ensembles with five Earth System Models (ESM-LE). We present evidence that a large fraction (~29–53%) of the simulated decadal-scale variance in individual timeseries of GMSST over 1950–2010 is externally forced and largely linked to the representation of volcanic aerosols. Comparison with the future (2010–2070) period suggests that external forcing provides a source of additional decadal-scale variability in the historical period. Given the unpredictable nature of future volcanic aerosol forcing, it is suggested that a large portion of decadal GMSST variability might not be predictable.

URLhttp://dx.doi.org/10.1038/s41467-020-17683-7
DOI10.1038/s41467-020-17683-7
Journal: Nature Communications
Year of Publication: 2020
Volume: 11
Number: 1
Publication Date: 07/2020

Despite the observed monotonic increase in greenhouse-gas concentrations, global mean temperature displays important decadal fluctuations typically attributed to both external forcing and internal variability. Here, we provide a robust quantification of the relative contributions of anthropogenic, natural, and internally-driven decadal variability of global mean sea surface temperature (GMSST) by using a unique dataset consisting of 30-member large initial-condition ensembles with five Earth System Models (ESM-LE). We present evidence that a large fraction (~29–53%) of the simulated decadal-scale variance in individual timeseries of GMSST over 1950–2010 is externally forced and largely linked to the representation of volcanic aerosols. Comparison with the future (2010–2070) period suggests that external forcing provides a source of additional decadal-scale variability in the historical period. Given the unpredictable nature of future volcanic aerosol forcing, it is suggested that a large portion of decadal GMSST variability might not be predictable.

DOI: 10.1038/s41467-020-17683-7
Citation:
Liguori, G, S McGregor, J Arblaster, M Singh, and G Meehl.  2020.  "A Joint Role for Forced and Internally-Driven Variability in the Decadal Modulation of Global Warming."  Nature Communications 11(1).  https://doi.org/10.1038/s41467-020-17683-7.