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1. Global mean surface temperature and climate sensitivity of the early Eocene Climatic Optimum (EECO), Paleocene–Eocene Thermal Maximum (PETM), and latest Paleocene

   https://doi.org/10.5194/cp-16-1953-2020  

   Inglis, Gordon N. ; Bragg, Fran ; Burls, Natalie J. ; Cramwinckel, Margot J. ; Evans, David ; Foster, Gavin L. ; Huber, Matthew ; Lunt, Daniel J. ; Siler, Nicholas ; Steinig, Sebastian ; et al ( January 2020 , Climate of the Past)

   null (Ed.)

   Abstract. Accurate estimates of past global mean surface temperature (GMST) help tocontextualise future climate change and are required to estimate thesensitivity of the climate system to CO2 forcing through Earth's history.Previous GMST estimates for the latest Paleocene and early Eocene(∼57 to 48 million years ago) span a wide range(∼9 to 23 ∘C higher than pre-industrial) andprevent an accurate assessment of climate sensitivity during this extremegreenhouse climate interval. Using the most recent data compilations, weemploy a multi-method experimental framework to calculate GMST during thethree DeepMIP target intervals: (1) the latest Paleocene (∼57 Ma), (2) the Paleocene–Eocene Thermal Maximum (PETM; 56 Ma), and (3) the earlyEocene Climatic Optimum (EECO; 53.3 to 49.1 Ma). Using six differentmethodologies, we find that the average GMST estimate (66 % confidence)during the latest Paleocene, PETM, and EECO was 26.3 ∘C (22.3 to28.3 ∘C), 31.6 ∘C (27.2 to 34.5 ∘C), and27.0 ∘C (23.2 to 29.7 ∘C), respectively. GMST estimatesfrom the EECO are ∼10 to 16 ∘C warmer thanpre-industrial, higher than the estimate given by the Intergovernmental Panel on Climate Change (IPCC) 5thAssessment Report (9 to 14 ∘C higher than pre-industrial).Leveraging the large “signal” associated with these extreme warm climates,we combine estimates of GMST and CO2 from the latest Paleocene, PETM,and EECO to calculate gross estimates of the average climate sensitivitybetween the early Paleogene and today. We demonstrate that “bulk”equilibrium climate sensitivity (ECS; 66 % confidence) during the latestPaleocene, PETM, and EECO is 4.5 ∘C (2.4 to 6.8 ∘C),3.6 ∘C (2.3 to 4.7 ∘C), and 3.1 ∘C (1.8 to4.4 ∘C) per doubling of CO2. These values are generallysimilar to those assessed by the IPCC (1.5 to 4.5 ∘C per doublingCO2) but appear incompatible with low ECS values (<1.5 perdoubling CO2). 

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2. The Magnitude of Surface Ocean Acidification and Carbon Release During Eocene Thermal Maximum 2 (ETM‐2) and the Paleocene‐Eocene Thermal Maximum (PETM)

   https://doi.org/10.1029/2019PA003699  

   Harper, D. T. ; Hönisch, B. ; Zeebe, R. E. ; Shaffer, G. ; Haynes, L. L. ; Thomas, E. ; Zachos, J. C. ( February 2020 , Paleoceanography and Paleoclimatology)
3. SEDIMENT ASSIMILATION EXERTS PRIMARY CONTROL ON HF ISOTOPE RATIOS IN THE PALEOCENE-EOCENE SANAK-BARANOF PLUTONIC BELT, ALASKA

   https://doi.org/10.1130/abs/2019CD-329682  

   Davidson, Cameron ; Garver, John I. ( January 2019 , Geological Society of America Abstracts with Programs)
4. Response of calcareous nannoplankton to the Paleocene–Eocene Thermal Maximum in the Paratethys Seaway (Tarim Basin, West China)

   https://doi.org/10.1016/j.gloplacha.2022.103918  

   Wang, Yasu ; Cui, Ying ; Su, Hong ; Jiang, Jingxin ; Wang, Yang ; Yang, Zhilin ; Hu, Xiumian ; Jiang, Shijun ( October 2022 , Global and Planetary Change)
5. Solar System chaos and the Paleocene–Eocene boundary age constrained by geology and astronomy

   https://doi.org/10.1126/science.aax0612  

   Zeebe, Richard E. ; Lourens, Lucas J. ( August 2019 , Science)

   Astronomical calculations reveal the Solar System’s dynamical evolution, including its chaoticity, and represent the backbone of cyclostratigraphy and astrochronology. An absolute, fully calibrated astronomical time scale has hitherto been hampered beyond ~50 million years before the present (Ma) because orbital calculations disagree before that age. Here, we present geologic data and a new astronomical solution (ZB18a) showing exceptional agreement from ~58 to 53 Ma. We provide a new absolute astrochronology up to 58 Ma and a new Paleocene–Eocene boundary age (56.01 ± 0.05 Ma). We show that the Paleocene–Eocene Thermal Maximum (PETM) onset occurred near a 405-thousand-year (kyr) eccentricity maximum, suggesting an orbital trigger. We also provide an independent PETM duration (170 ± 30 kyr) from onset to recovery inflection. Our astronomical solution requires a chaotic resonance transition at ~50 Ma in the Solar System’s fundamental frequencies. 

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