Palaeoclimate constraints on the impact of 2 °C anthropogenic warming and beyond
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Hubertus Fischer
- Function : Author
- PersonId : 755228
- ORCID : 0000-0002-2787-4221
Victor Brovkin
- Function : Author
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- ORCID : 0000-0001-6420-3198
- IdRef : 200260626
Anne Daniau
- Function : Author
- PersonId : 174590
- IdHAL : anne-laure-daniau
- ORCID : 0000-0002-1621-3911
- IdRef : 12852538X
Thomas Felis
- Function : Author
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- ORCID : 0000-0003-1417-9657
Thibaut Caley
- Function : Author
- PersonId : 738443
- IdHAL : thibaut-caley
- ORCID : 0000-0001-8249-7054
Anne de Vernal
- Function : Author
- PersonId : 766752
- ORCID : 0000-0001-5656-724X
- IdRef : 117823406
Julien Emile-Geay
- Function : Author
- PersonId : 781741
- ORCID : 0000-0001-5920-4751
Fortunat Joos
- Function : Author
- PersonId : 757568
- ORCID : 0000-0002-9483-6030
Daniel Lunt
- Function : Author
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- ORCID : 0000-0003-3585-6928
Katarzyna Marcisz
- Function : Author
- PersonId : 773164
- ORCID : 0000-0003-2655-9729
Matias Martinez
- Function : Author
- PersonId : 1164245
- IdHAL : martinezmatias
- ORCID : 0000-0002-2945-866X
Valérie Masson-Delmotte
- Function : Author
- PersonId : 859531
Christoph Nehrbass-Ahles
- Function : Author
- PersonId : 790997
- ORCID : 0000-0002-4009-4633
Bette Otto-Bliesner
- Function : Author
- PersonId : 772224
- ORCID : 0000-0003-1911-1598
Thomas Stocker
- Function : Author
- PersonId : 1007117
Martin Ziegler
- Function : Author
- PersonId : 945585
Abstract
Over the past 3.5 million years, there have been several intervals when climate conditions were warmer than during the pre-industrial Holocene. Although past intervals of warming were forced differently than future anthropogenic change, such periods can provide insights into potential future climate impacts and ecosystem feedbacks, especially over centennial-to-millennial timescales that are often not covered by climate model simulations. Our observation-based synthesis of the understanding of past intervals with temperatures within the range of projected future warming suggests that there is a low risk of runaway greenhouse gas feedbacks for global warming of no more than 2 °C. However, substantial regional environmental impacts can occur. A global average warming of 1–2 °C with strong polar amplification has, in the past, been accompanied by significant shifts in climate zones and the spatial distribution of land and ocean ecosystems. Sustained warming at this level has also led to substantial reductions of the Greenland and Antarctic ice sheets, with sea-level increases of at least several metres on millennial timescales. Comparison of palaeo observations with climate model results suggests that, due to the lack of certain feedback processes, model-based climate projections may underestimate long-term warming in response to future radiative forcing by as much as a factor of two, and thus may also underestimate centennial-to-millennial-scale sea-level rise.
Origin : Publisher files allowed on an open archive
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