Comparative carbon cycle dynamics between the present and last interglacial

• Published in: Quaternary Science Reviews
• Main Authors: Brovkin, Victor, Brücher, Tim, Kleinen, Thomas, Zaehle, Sönke, Joos, Fortunat, Roth, Raphael, Spahni, Renato, Schmitt, Jochen, Fischer, Hubertus, Leuenberger, Markus, Stone, Emma J., Ridgwell, Andy, Chappellaz, Jerome, Kehrwald, Natalie, Barbante, Carlo, Blunier, Thomas, Dahl Jensen, Dorthe
• Format: Article in Journal/Newspaper
• Language: English
• Published: Elsevier 2016
• Subjects: Antarctic; Antarc*; Ice; permafrost
• Online Access: https://oceanrep.geomar.de/id/eprint/31188/; https://oceanrep.geomar.de/id/eprint/31188/1/1-s2.0-S0277379116300300-main.pdf; https://oceanrep.geomar.de/id/eprint/31188/2/mmc1.docx; https://doi.org/10.1016/j.quascirev.2016.01.028

Highlights: • We provide comprehensive discussion of carbon cycle forcings in interglacials. • We compare transient simulations of climate-carbon cycle models through Holocene and Eemian interglacials. • We synthesyze role of forcings in previous and current study in one summary figure. Abstract: Changes in temperature and carbon dioxide during glacial cycles recorded in Antarctic ice cores are tightly coupled. However, this relationship does not hold for interglacials. While climate cooled towards the end of both the last (Eemian) and present (Holocene) interglacials, CO2 remained stable during the Eemian while rising in the Holocene. We identify and review twelve biogeochemical mechanisms of terrestrial (vegetation dynamics and CO2 fertilization, land use, wildfire, accumulation of peat, changes in permafrost carbon, subaerial volcanic outgassing) and marine origin (changes in sea surface temperature, carbonate compensation to deglaciation and terrestrial biosphere regrowth, shallow-water carbonate sedimentation, changes in the soft tissue pump, and methane hydrates), which potentially may have contributed to the CO2 dynamics during interglacials but which remain not well quantified. We use three Earth System Models (ESMs) of intermediate complexity to compare effects of selected mechanisms on the interglacial CO2 and δ13CO2 changes, focusing on those with substantial potential impacts: namely carbonate sedimentation in shallow waters, peat growth, and (in the case of the Holocene) human land use. A set of specified carbon cycle forcings could qualitatively explain atmospheric CO2 dynamics from 8 ka BP to the pre-industrial. However, when applied to Eemian boundary conditions from 126 to 115 ka BP, the same set of forcings led to disagreement with the observed direction of CO2 changes after 122 ka BP. This failure to simulate late-Eemian CO2 dynamics could be a result of the imposed forcings such as prescribed CaCO3 accumulation and/or an incorrect response of simulated terrestrial carbon to the surface ...