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Raimund Muscheler

Raimund Muscheler

Professor

Raimund Muscheler

Tipping elements and amplified polar warming during the Last Interglacial

Författare

  • Zoë A. Thomas
  • Richard T. Jones
  • Chris S.M. Turney
  • Nicholas Golledge
  • Christopher Fogwill
  • Corey J.A. Bradshaw
  • Laurie Menviel
  • Nicholas P. McKay
  • Michael Bird
  • Jonathan Palmer
  • Peter Kershaw
  • Janet Wilmshurst
  • Raimund Muscheler

Summary, in English

Irreversible shifts of large-scale components of the Earth system (so-called ‘tipping elements’) on policy-relevant timescales are a major source of uncertainty for projecting the impacts of future climate change. The high latitudes are particularly vulnerable to positive feedbacks that amplify change through atmosphere-ocean-ice interactions. Unfortunately, the short instrumental record does not capture the full range of past or projected climate scenarios (a situation particularly acute in the high latitudes). Natural archives from past periods warmer than present day, however, can be used to explore drivers and responses to forcing, and provide data against which to test models, thereby offering insights into the future. The Last Interglacial (129–116,000 years before present) — the warmest interglacial of the last 800,000 years — was the most recent period during which global temperatures were comparable with low-end 21st Century projections (up to 2 °C warmer, with temperature increase amplified over polar latitudes), providing a potentially useful analogue for future change. Substantial environmental changes happened during this time. Here we synthesise the nature and timing of potential high-latitude tipping elements during the Last Interglacial, including sea ice, extent of the boreal forest, permafrost, ocean circulation, and ice sheets/sea level. We also review the thresholds and feedbacks that likely operated through this period. Notably, substantial ice mass loss from Greenland, the West Antarctic, and possibly sectors of the East Antarctic drove a 6–9 m rise in global sea level. This was accompanied by reduced summer sea-ice extent, poleward-extended boreal forest, and reduced areas of permafrost. Despite current chronological uncertainties, we find that tipping elements in the high latitudes all experienced rapid and abrupt change (within 1–2 millennia of each other) across both hemispheres, while recovery to prior conditions took place over multi-millennia. Our synthesis demonstrates important feedback loops between tipping elements, amplifying polar and global change during the Last Interglacial. The high sensitivity and tight interconnections between polar tipping elements suggests that they could exhibit similar thresholds of vulnerability in the future, particularly if the aspirations of the Paris Agreement are not met.

Avdelning/ar

  • Kvartärgeologi
  • MERGE: ModElling the Regional and Global Earth system
  • BECC: Biodiversity and Ecosystem services in a Changing Climate

Publiceringsår

2020-04-01

Språk

Engelska

Publikation/Tidskrift/Serie

Quaternary Science Reviews

Volym

233

Dokumenttyp

Artikel i tidskrift

Förlag

Elsevier

Ämne

  • Climate Research

Status

Published

ISBN/ISSN/Övrigt

  • ISSN: 0277-3791