Preprints
https://doi.org/10.5194/egusphere-2024-1691
https://doi.org/10.5194/egusphere-2024-1691
19 Jun 2024
 | 19 Jun 2024
Status: this preprint is open for discussion and under review for Climate of the Past (CP).

Speleothem evidence for late Miocene extreme Arctic amplification – an analogue for near future anthropogenic climate change?

Stuart Umbo, Franziska Lechleitner, Thomas Opel, Sevasti Modestou, Tobias Braun, Anton Vaks, Gideon Henderson, Pete Scott, Alexander Osintzev, Alexandr Kononov, Irina Adrian, Yuri Dublyansky, Alena Giesche, and Sebastian Breitenbach

Abstract. The Miocene provides an excellent climatic analogue for near future anthropogenic warming, with atmospheric CO2 concentrations and global average temperatures similar to those projected for the coming century. However, the magnitude of Miocene Arctic warming remains unclear due to the scarcity of reliable proxy data. Here we use stable oxygen isotope and trace element analyses, alongside clumped isotope and fluid inclusion palaeothermometry of speleothems to reconstruct palaeo-environmental conditions near the Siberian Arctic coast during the late Tortonian (8.68 ± 0.09 Ma). Stable oxygen isotope records suggest warmer than present temperatures. This is supported by temperature estimates based on clumped isotopes and fluid inclusions giving mean annual air temperatures between +6.6 and +11.1 °C, compared with -12.3 °C today. Trace elements records reveal a highly seasonal hydrological environment.

Our estimate of >18 °C of Arctic warming supports the wider consensus of a warmer-than-present Miocene and provides a rare paleo-analogue for future Arctic amplification under high emissions scenarios. The reconstructed increase in mean surface temperature far exceeds those projected in fully coupled global climate models, even under extreme emissions scenarios. Given that climate models have consistently underestimated the extent of recent Arctic amplification, our proxy data suggest Arctic warming may exceed current projections. If Arctic warming by 2100 matches our late Miocene estimates, it would have large-scale impacts on global climate, including extensive thawing of Siberian permafrost – a vast fossil carbon store.

Publisher's note: Copernicus Publications remains neutral with regard to jurisdictional claims made in the text, published maps, institutional affiliations, or any other geographical representation in this preprint. The responsibility to include appropriate place names lies with the authors.
Stuart Umbo, Franziska Lechleitner, Thomas Opel, Sevasti Modestou, Tobias Braun, Anton Vaks, Gideon Henderson, Pete Scott, Alexander Osintzev, Alexandr Kononov, Irina Adrian, Yuri Dublyansky, Alena Giesche, and Sebastian Breitenbach

Status: open (until 14 Aug 2024)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • CC1: 'Comment on egusphere-2024-1691', Arthur Oldeman, 19 Jun 2024 reply
  • RC1: 'Comment on egusphere-2024-1691', Anonymous Referee #1, 09 Jul 2024 reply
  • RC2: 'Comment on egusphere-2024-1691', Julian Murton, 18 Jul 2024 reply
Stuart Umbo, Franziska Lechleitner, Thomas Opel, Sevasti Modestou, Tobias Braun, Anton Vaks, Gideon Henderson, Pete Scott, Alexander Osintzev, Alexandr Kononov, Irina Adrian, Yuri Dublyansky, Alena Giesche, and Sebastian Breitenbach
Stuart Umbo, Franziska Lechleitner, Thomas Opel, Sevasti Modestou, Tobias Braun, Anton Vaks, Gideon Henderson, Pete Scott, Alexander Osintzev, Alexandr Kononov, Irina Adrian, Yuri Dublyansky, Alena Giesche, and Sebastian Breitenbach

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Short summary
We use cave rocks to reconstruct northern Siberian climate 8.68 ± 0.09 million years ago. We show that when global average temperature was about 4.5 °C warmer than today (similar to what’s expected in the coming decades should carbon emissions continue unabated), Arctic temperature increased by more than 18 °C. Similar levels of Arctic warming in the future would see huge areas of permafrost (permanently frozen ground) thaw and release greenhouse gases to the atmosphere.