Preprints
https://doi.org/10.5194/cp-2021-78
https://doi.org/10.5194/cp-2021-78

  05 Aug 2021

05 Aug 2021

Review status: this preprint is currently under review for the journal CP.

The blue suns of 1831: was the eruption of Ferdinandea, near Sicily, one of the largest volcanic climate forcing events of the nineteenth century?

Christopher Garrison, Christopher Kilburn, David Smart, and Stephen Edwards Christopher Garrison et al.
  • UCL Hazard Centre, Department of Earth Sciences, University College London, Gower Street, London, WC1E 6BT, UK

Abstract. One of the largest climate forcing eruptions of the nineteenth century was, until recently, believed to have taken place at Babuyan Claro volcano, in the Philippines, in 1831. However, a recent investigation found no reliable evidence of such an eruption, suggesting that the 1831 eruption must have taken place elsewhere. A newly compiled dataset of reported observations of a blue, purple and green sun in August 1831 is here used to reconstruct the transport of a stratospheric aerosol plume from that eruption. The source of the aerosol plume is identified as the eruption of Ferdinandea, which took place about 50 km off the south-west coast of Sicily (lat. 37.1° N., long. 12.7° E.), in July and August 1831. The modest magnitude of this eruption, assigned a Volcanic Explosivity Index (VEI) of 3, has commonly caused it to be discounted or overlooked when identifying the likely source of the stratospheric sulphate aerosol in 1831. It is proposed, however, that convective instability in the troposphere contributed to aerosol reaching the stratosphere and that the aerosol load was enhanced by addition of a sedimentary sulphur component to the volcanic plume. One of the largest climate forcing volcanic eruptions of the nineteenth century would thus effectively have been hiding in plain sight, arguably ‘lowering the bar’ for the types of eruptions capable of having a substantial climate forcing impact. Prior estimates of the mass of stratospheric sulphate aerosol responsible for the 1831 Greenland ice-core sulphate deposition peaks which have assumed a source eruption at a low-latitude site will therefore have been overstated. The example presented in this paper serves as a useful reminder that VEI values were not intended to be reliably correlated with eruption sulphur yields unless supplemented with compositional analyses. It also underlines that eye-witness accounts of historical geophysical events should not be neglected as a source of valuable scientific data.

Christopher Garrison et al.

Status: open (until 03 Oct 2021)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on cp-2021-78', Anonymous Referee #1, 20 Aug 2021 reply
  • RC2: 'Comment on cp-2021-78', Fred Prata, 02 Sep 2021 reply
  • RC3: 'Comment on cp-2021-78', Anonymous Referee #3, 09 Sep 2021 reply

Christopher Garrison et al.

Christopher Garrison et al.

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Short summary
An unidentified eruption in 1831 was one of the largest volcanic climate forcing events of the nineteenth century. We use reported observations of a blue sun to reconstruct the transport of an aerosol plume from that eruption and, hence, identify it as the 1831 eruption of Ferdinandea, near Sicily. We propose that, although it was only a modest eruption, its volcanic plume was enriched with sulphur from sedimentary deposits and that meteorological conditions helped it reach the stratosphere.