Underestimation of volcanic cooling in tree-ring-based reconstructions of hemispheric temperatures

Michael E. Mann, Jose D. Fuentes, Scott Rutherford

Research output: Contribution to journalArticle

100 Citations (Scopus)

Abstract

The largest eruption of a tropical volcano during the past millennium occurred in AD 1258-1259. Its estimated radiative forcing was several times larger than the 1991 Pinatubo eruption 1. Radiative forcing of that magnitude is expected to result in a climate cooling of about 2 °C (refs 2-5). This effect, however, is largely absent from tree-ring reconstructions of temperature 6-8, and is muted in reconstructions that employ a mix of tree-rings and other proxy data 9,10. This discrepancy has called into question the climate impact of the eruption 2,5,11. Here we use a tree-growth model driven by simulated temperature variations to show that the discrepancy between expected and reconstructed temperatures is probably an artefact caused by a reduced sensitivity to cooling in trees that grow near the treeline. This effect is compounded by the secondary effects of chronological errors due to missing growth rings and volcanically induced alterations of diffuse light. We support this conclusion with an assessment of synthetic proxy records created using the simulated temperature variations. Our findings suggest that the evidence from tree rings is consistent with a substantial climate impact 2-5 of volcanic eruptions in past centuries that is greater than that estimated by tree-ring-based temperature reconstructions.

Original languageEnglish (US)
Pages (from-to)202-205
Number of pages4
JournalNature Geoscience
Volume5
Issue number3
DOIs
StatePublished - Mar 1 2012

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tree ring
cooling
volcanic eruption
climate effect
radiative forcing
temperature
treeline
artifact
volcano
climate
effect

All Science Journal Classification (ASJC) codes

  • Earth and Planetary Sciences(all)

Cite this

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abstract = "The largest eruption of a tropical volcano during the past millennium occurred in AD 1258-1259. Its estimated radiative forcing was several times larger than the 1991 Pinatubo eruption 1. Radiative forcing of that magnitude is expected to result in a climate cooling of about 2 °C (refs 2-5). This effect, however, is largely absent from tree-ring reconstructions of temperature 6-8, and is muted in reconstructions that employ a mix of tree-rings and other proxy data 9,10. This discrepancy has called into question the climate impact of the eruption 2,5,11. Here we use a tree-growth model driven by simulated temperature variations to show that the discrepancy between expected and reconstructed temperatures is probably an artefact caused by a reduced sensitivity to cooling in trees that grow near the treeline. This effect is compounded by the secondary effects of chronological errors due to missing growth rings and volcanically induced alterations of diffuse light. We support this conclusion with an assessment of synthetic proxy records created using the simulated temperature variations. Our findings suggest that the evidence from tree rings is consistent with a substantial climate impact 2-5 of volcanic eruptions in past centuries that is greater than that estimated by tree-ring-based temperature reconstructions.",
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Underestimation of volcanic cooling in tree-ring-based reconstructions of hemispheric temperatures. / Mann, Michael E.; Fuentes, Jose D.; Rutherford, Scott.

In: Nature Geoscience, Vol. 5, No. 3, 01.03.2012, p. 202-205.

Research output: Contribution to journalArticle

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