scholarly journals Frequency, magnitude and character of hyperthermal events at the onset of the Early Eocene Climatic Optimum

2015 ◽  
Vol 11 (3) ◽  
pp. 1795-1820 ◽  
Author(s):  
V. Lauretano ◽  
K. Littler ◽  
M. Polling ◽  
J. C. Zachos ◽  
L. J. Lourens
Keyword(s):  
Water Mass ◽  
Intermediate Water ◽  
Early Eocene ◽  
Walvis Ridge ◽  
Early Eocene Climatic Optimum ◽  
Thermal Maximum ◽  
Carbon And Oxygen Isotope ◽  
Hyperthermal Events ◽  
Climatic Optimum ◽  
Δ13c And Δ18o

Abstract. Recent studies have shown that the Early Eocene Climatic Optimum (EECO) was preceded by a series of short-lived global warming events, known as hyperthermals. Here we present high-resolution benthic stable carbon and oxygen isotope records from ODP Sites 1262 and 1263 (Walvis Ridge, SE Atlantic) between ∼54 and ∼52 million years ago, tightly constraining the character, timing, and magnitude of six prominent hyperthermal events. These events, that include Eocene Thermal Maximum (ETM) 2 and 3, are studied in relation to orbital forcing and long-term trends. Our findings reveal an almost linear relationship between δ13C and δ18O for all these hyperthermals, indicating that the eccentricity-paced co-variance between extreme perturbations in the exogenic carbon pool and deep-sea temperatures persisted during the onset of the EECO, in accord with previous observations for the Paleocene Eocene Thermal Maximum (PETM) and ETM2. The covariance of δ13C and δ18O during H2 and I2, which are the second pulses of the "paired" hyperthermal events ETM2-H2 and I1-I2, deviates with respect to the other events. This could relate to a relatively higher contribution of an isotopically heavier source of carbon, such as peat or permafrost, and/or to climate feedbacks/local changes in circulation. Finally, the δ18O records of the two sites show a systematic offset with on average 0.2‰ heavier values for the shallower Site 1263, which we link to a slightly heavier (e.g. more saline) isotope composition of the intermediate water mass reaching the northeastern flank of the Walvis Ridge compared to that of the deeper northwestern water mass at Site 1262.

scholarly journals Frequency, magnitude and character of hyperthermal events at the onset of the Early Eocene Climatic Optimum

2015 ◽  
Vol 11 (10) ◽  
pp. 1313-1324 ◽  
Author(s):  
V. Lauretano ◽  
K. Littler ◽  
M. Polling ◽  
J. C. Zachos ◽  
L. J. Lourens
Keyword(s):  
Water Mass ◽  
Intermediate Water ◽  
Early Eocene ◽  
Walvis Ridge ◽  
Early Eocene Climatic Optimum ◽  
Thermal Maximum ◽  
Carbon And Oxygen Isotope ◽  
Hyperthermal Events ◽  
Climatic Optimum ◽  
Δ13c And Δ18o

Abstract. Recent studies have shown that the Early Eocene Climatic Optimum (EECO) was preceded by a series of short-lived global warming events, known as hyperthermals. Here we present high-resolution benthic stable carbon and oxygen isotope records from ODP Sites 1262 and 1263 (Walvis Ridge, SE Atlantic) between ~ 54 and ~ 52 million years ago, tightly constraining the character, timing, and magnitude of six prominent hyperthermal events. These events, which include Eocene Thermal Maximum (ETM) 2 and 3, are studied in relation to orbital forcing and long-term trends. Our findings reveal an almost linear relationship between δ13C and δ18O for all these hyperthermals, indicating that the eccentricity-paced covariance between deep-sea temperature changes and extreme perturbations in the exogenic carbon pool persisted during these events towards the onset of the EECO, in accordance with previous observations for the Paleocene Eocene Thermal Maximum (PETM) and ETM2. The covariance of δ13C and δ18O during H2 and I2, which are the second pulses of the "paired" hyperthermal events ETM2-H2 and I1-I2, deviates with respect to the other events. We hypothesize that this could relate to a relatively higher contribution of an isotopically heavier source of carbon, such as peat or permafrost, and/or to climate feedbacks/local changes in circulation. Finally, the δ18O records of the two sites show a systematic offset with on average 0.2 ‰ heavier values for the shallower Site 1263, which we link to a slightly heavier isotopic composition of the intermediate water mass reaching the northeastern flank of the Walvis Ridge compared to that of the deeper northwestern water mass at Site 1262.

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

2020 ◽  
Vol 16 (5) ◽  
pp. 1953-1968 ◽  
Author(s):  
Gordon N. Inglis ◽  
Fran Bragg ◽  
Natalie J. Burls ◽  
Margot J. Cramwinckel ◽  
David Evans ◽  
...  
Keyword(s):  
Climate Change ◽  
Surface Temperature ◽  
Climate Sensitivity ◽  
Future Climate Change ◽  
Early Eocene ◽  
Early Eocene Climatic Optimum ◽  
Thermal Maximum ◽  
Global Mean Surface Temperature ◽  
Climatic Optimum ◽  
Global Mean

Abstract. Accurate estimates of past global mean surface temperature (GMST) help to contextualise future climate change and are required to estimate the sensitivity 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) and prevent an accurate assessment of climate sensitivity during this extreme greenhouse climate interval. Using the most recent data compilations, we employ a multi-method experimental framework to calculate GMST during the three DeepMIP target intervals: (1) the latest Paleocene (∼57 Ma), (2) the Paleocene–Eocene Thermal Maximum (PETM; 56 Ma), and (3) the early Eocene Climatic Optimum (EECO; 53.3 to 49.1 Ma). Using six different methodologies, we find that the average GMST estimate (66 % confidence) during the latest Paleocene, PETM, and EECO was 26.3 ∘C (22.3 to 28.3 ∘C), 31.6 ∘C (27.2 to 34.5 ∘C), and 27.0 ∘C (23.2 to 29.7 ∘C), respectively. GMST estimates from the EECO are ∼10 to 16 ∘C warmer than pre-industrial, higher than the estimate given by the Intergovernmental Panel on Climate Change (IPCC) 5th Assessment 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 sensitivity between the early Paleogene and today. We demonstrate that “bulk” equilibrium climate sensitivity (ECS; 66 % confidence) during the latest Paleocene, 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 to 4.4 ∘C) per doubling of CO2. These values are generally similar to those assessed by the IPCC (1.5 to 4.5 ∘C per doubling CO2) but appear incompatible with low ECS values (<1.5 per doubling CO2).

scholarly journals Major perturbations in the global carbon cycle and photosymbiont-bearing planktic foraminifera during the early Eocene

2016 ◽  
Vol 12 (4) ◽  
pp. 981-1007 ◽  
Author(s):  
Valeria Luciani ◽  
Gerald R. Dickens ◽  
Jan Backman ◽  
Eliana Fornaciari ◽  
Luca Giusberti ◽  
...  
Keyword(s):  
Carbon Cycle ◽  
Northwest Pacific ◽  
Early Eocene ◽  
Ocean Drilling Program ◽  
Low Latitude ◽  
Planktic Foraminifera ◽  
Early Eocene Climatic Optimum ◽  
Carbon And Oxygen Isotope ◽  
Hyperthermal Events ◽  
Global Carbon

Abstract. A marked switch in the abundance of the planktic foraminiferal genera Morozovella and Acarinina occurred at low-latitude sites near the start of the Early Eocene Climatic Optimum (EECO), a multi-million-year interval when Earth surface temperatures reached their Cenozoic maximum. Stable carbon and oxygen isotope data of bulk sediment are presented from across the EECO at two locations: Possagno in northeast Italy and Deep Sea Drilling Project (DSDP) Site 577 in the northwest Pacific. Relative abundances of planktic foraminifera are presented from these two locations, as well as from Ocean Drilling Program (ODP) Site 1051 in the northwest Atlantic. All three sections have good stratigraphic markers, and the δ13C records at each section can be correlated amongst each other and to δ13C records at other locations across the globe. These records show that a series of negative carbon isotope excursions (CIEs) occurred before, during and across the EECO, which is defined here as the interval between the J event and the base of Discoaster sublodoensis. Significant though ephemeral modifications in planktic foraminiferal assemblages coincide with some of the short-term CIEs, which were marked by increases in the relative abundance of Acarinina, similar to what happened across established hyperthermal events in Tethyan settings prior to the EECO. Most crucially, a temporal link exists between the onset of the EECO, carbon cycle changes during this time and the decline in Morozovella. Possible causes are manifold and may include temperature effects on photosymbiont-bearing planktic foraminifera and changes in ocean chemistry.

scholarly journals Temperature seasonality in the North American continental interior during the early Eocene climatic optimum

2018 ◽  
Author(s):  
Ethan G. Hyland ◽  
Katharine W. Huntington ◽  
Nathan D. Sheldon ◽  
Tammo Reichgelt
Keyword(s):  
Climate Model ◽  
Regional Climate ◽  
Early Eocene ◽  
Early Eocene Climatic Optimum ◽  
The North ◽  
Annual Range ◽  
Climatic Optimum ◽  
Temperature Records ◽  
Model Ensembles ◽  
Continental Interior

Abstract. Paleogene greenhouse climate equability has long been a paradox in paleoclimate research. However, recent developments in proxy and modeling methods have suggested that strong seasonality may be a feature of at least some greenhouse periods. Here we present the first multi-proxy record of seasonal temperatures during the Paleogene from paleofloras, paleosol geochemistry, and carbonate clumped isotope thermometry in the Green River Basin (Wyoming, USA). These combined temperature records allow for the reconstruction of past seasonality in the continental interior, which shows that temperatures were warmer in all seasons during the peak early Eocene climatic optimum and that the mean annual range of temperature was high, similar to the modern value (~ 26 °C). Proxy data and downscaled Eocene regional climate model results suggest amplified seasonality during greenhouse events. Increased seasonality reconstructed for the early Eocene is similar in scope to the higher seasonal range predicted by downscaled climate model ensembles for future high-CO2 emissions scenarios. Overall, these data and model comparisons have substantial implications for understanding greenhouse climates in general, and may be important for predicting future seasonal climate regimes and their impacts in continental regions.

Exploring the possible meridional temperature gradient of Early Eocene Climatic Optimum with an energy balance model

2021 ◽  
Author(s):  
Fanni Dora Kelemen ◽  
Bodo Ahrens
Keyword(s):  
Energy Balance ◽  
Temperature Gradient ◽  
Entropy Production ◽  
Maximum Entropy ◽  
Early Eocene ◽  
Meridional Temperature Gradient ◽  
Proxy Data ◽  
Maximum Entropy Production ◽  
Early Eocene Climatic Optimum ◽  
Climatic Optimum

&lt;p&gt;Early Eocene Climatic Optimum (EECO, ~53-51 million years) is one of the past warm periods, associated with high CO&lt;sub&gt;2&lt;/sub&gt; concentrations (~900-2500 ppmv), which can serve as an analogue for our possible future, high C0&lt;sub&gt;2 &lt;/sub&gt;climate. One notable feature of this hothouse climate state is the weaker meridional temperature gradient relative to pre-industrial values. This have been confirmed by both proxies and models, but the extent of the temperature gradient still requires more research. Models are challenged to reproduce the stronger than present day polar amplification signal, and it is also shown that high latitude proxy data are often influenced by seasonal bias. Thus, there is an uncertainty regarding both the observed and modelled meridional gradient and the mentioned issues complicate also the comparison between modeled and proxy data.&lt;/p&gt;&lt;p&gt;In our work we aim to investigate the EECO period with a simple energy balance box model and apply the maximum entropy production principle to explore the possible scenarios of meridional temperature gradients. We find that the maximum entropy production principle could be beneficial in the paleoclimate context since it has the utility to give an accurate prediction for non-equilibrium systems with the minimal amount of information. We also assess the heat transport signaled by proxy data and by state-of-the-art model outputs in accordance to our theoretical constrains based on the idealized test case.&lt;/p&gt;

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