A joint role for forced and internally-driven variability in the decadal modulation of global warming

Giovanni Liguori; Shayne McGregor; Julie M. Arblaster; Martin S. Singh; Gerald A. Meehl

doi:10.1038/s41467-020-17683-7

A joint role for forced and internally-driven variability in the decadal modulation of global warming

Giovanni Liguori
, Shayne McGregor
, Julie M. Arblaster
, Martin S. Singh
, Gerald A. Meehl

School of Earth Atmosphere and Environment

Research output: Contribution to journal › Article › Research › peer-review

27 Citations (Scopus)

Abstract

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.

Original language	English
Article number	3827
Number of pages	7
Journal	Nature Communications
Volume	11
Issue number	1
DOIs	https://doi.org/10.1038/s41467-020-17683-7
Publication status	Published - 31 Jul 2020

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10.1038/s41467-020-17683-7Licence: CC BY

316644748-oaFinal published version, 2.59 MBLicence: CC BY

Cite this

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title = "A joint role for forced and internally-driven variability in the decadal modulation of global warming",

abstract = "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 (\textasciitilde{}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.",

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AU - Liguori, Giovanni

AU - McGregor, Shayne

AU - Arblaster, Julie M.

AU - Singh, Martin S.

AU - Meehl, Gerald A.

PY - 2020/7/31

Y1 - 2020/7/31

N2 - 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.

AB - 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.

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A joint role for forced and internally-driven variability in the decadal modulation of global warming

Abstract

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ARC Centre of Excellence for Climate Extremes

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A joint role for forced and internally-driven variability in the decadal modulation of global warming

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ARC Centre of Excellence for Climate Extremes

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