Reduced carbon cycle resilience across the Palaeocene-Eocene Thermal Maximum

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doi: 10.5194/cp-14-1515-2018
Author(s): Armstrong McKay, David I.; Lenton, Timothy M.
Author Affiliation(s): Primary:
University of Southampton, National Oceanography Centre Southampton, Southampton, United Kingdom
Other:
University of Exeter, United Kingdom
Volume Title: Climate of the Past
Source: Climate of the Past, 14(10), p.1515-1527. Publisher: Copernicus, Katlenburg-Lindau, International. ISSN: 1814-9324
Note: In English. 92 refs.; illus., incl. 1 table
Summary: Several past episodes of rapid carbon cycle and climate change are hypothesised to be the result of the Earth system reaching a tipping point beyond which an abrupt transition to a new state occurs. At the Palaeocene-Eocene Thermal Maximum (PETM) at ∼ 56 Ma and at subsequent hyperthermal events, hypothesised tipping points involve the abrupt transfer of carbon from surface reservoirs to the atmosphere. Theory suggests that tipping points in complex dynamical systems should be preceded by critical slowing down of their dynamics, including increasing temporal autocorrelation and variability. However, reliably detecting these indicators in palaeorecords is challenging, with issues of data quality, false positives, and parameter selection potentially affecting reliability. Here we show that in a sufficiently long, high-resolution palaeorecord there is consistent evidence of destabilisation of the carbon cycle in the ∼ 1.5 Myr prior to the PETM, elevated carbon cycle and climate instability following both the PETM and Eocene Thermal Maximum 2 (ETM2), and different drivers of carbon cycle dynamics preceding the PETM and ETM2 events. Our results indicate a loss of "resilience" (weakened stabilising negative feedbacks and greater sensitivity to small shocks) in the carbon cycle before the PETM and in the carbon-climate system following it. This pre-PETM carbon cycle destabilisation may reflect gradual forcing by the contemporaneous North Atlantic Volcanic Province eruptions, with volcanism-driven warming potentially weakening the organic carbon burial feedback. Our results are consistent with but cannot prove the existence of a tipping point for abrupt carbon release, e.g. from methane hydrate or terrestrial organic carbon reservoirs, whereas we find no support for a tipping point in deep ocean temperature.
Year of Publication: 2018
Research Program: ODP Ocean Drilling Program
Key Words: 02 Geochemistry; 12 Stratigraphy, Historical Geology and Paleoecology; Atlantic Ocean; C-13/C-12; Carbon; Carbon cycle; Carbon dioxide; Cenozoic; Climate change; Correlation; Cycles; Feedback; Geochemical cycle; Isotope ratios; Isotopes; Leg 208; O-18/O-16; ODP Site 1262; Ocean Drilling Program; Oxygen; Paleocene-Eocene Thermal Maximum; Paleoclimatology; Paleoenvironment; Paleogene; Paleotemperature; South Atlantic; Stable isotopes; Statistical analysis; Tertiary; Walvis Ridge
Coordinates: S271100 S271100 E0013500 E0013400
Record ID: 2019051805
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from Copernicus Gesellschaft, Katlenburg-Lindau, Germany