Climate sensitivity and meridional overturning circulation in the late Eocene using GFDL CM2.1

Hutchinson, David K.; Boer, Agatha M. de; Coxall, Helen; Caballero, Rodrigo; Nilsson, Johan; Baatsen, Michiel

doi:10.5194/cp-14-789-2018

Cited by 63 publications

(103 citation statements)

References 104 publications

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“…Likewise, Figure 3 shows absolute values and mean changes for variables relating to ocean overturning, specifically, the maximum depth of the mixed layer in the Southern Ocean (Figures 3a and 3b) and North Atlantic (Figures 3c and 3d) and maximum overturning strength in the Southern (Figures 3e and 3f) and Northern (Figures 3g and 3h) Hemispheres. Unlike the results of Hutchinson et al (2018), none of the simulations here suggest overturning in the North Pacific. The simulations here generally have lower sea surface salinities and a much shallower mixed layer depth (MLD) in the Pacific than in the Atlantic, suggesting that overturning is absent from this region (figures of North Pacific MLD and salinity not shown).…”

Section: Boundary Condition Sensitivitycontrasting

confidence: 99%

Assessing Mechanisms and Uncertainty in Modeled Climatic Change at the Eocene‐Oligocene Transition

Kennedy-Asser

Lunt

Farnsworth

et al. 2019

Paleoceanog and Paleoclimatol

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The Earth system changed dramatically across the Eocene‐Oligocene Transition (EOT) on a variety of spatial and temporal scales. Understanding the many complex and interacting factors affecting the Earth's atmosphere and oceans at the EOT requires the combination of both data and modeling approaches and an understanding of the uncertainty in both of these elements. Here uncertainty in the Earth system response to various imposed forcings typical of changes at the EOT is assessed. By using an ensemble of simulations from the fully coupled general circulation model, HadCM3L, the uncertainty due to differences in the boundary conditions and insufficient model spin‐up is quantified. The surface temperature response in high‐latitude ocean regions, particularly where deep water formation occurs, is found to be highly sensitive to differences in boundary conditions (i.e., have the greatest magnitude of uncertainty), while low‐latitude oceans are the most insensitive to differences in boundary conditions (i.e., have the lowest magnitude of uncertainty). The length of spin‐up (or how far the model is from equilibrium) can have a significant effect on the response to some forcings and on the magnitude of uncertainty due to differences in boundary conditions. These findings are important to consider for future modeling work and for interpreting previous published simulations.

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Section: Boundary Condition Sensitivitycontrasting

confidence: 99%

Assessing Mechanisms and Uncertainty in Modeled Climatic Change at the Eocene‐Oligocene Transition

Kennedy-Asser

Lunt

Farnsworth

et al. 2019

Paleoceanog and Paleoclimatol

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“…This bias is similar to other higher-resolution variants of the model (Valdes et al, 2017). FOAM has been shown to capture most of the major characteristics of present-day climatology (Jacob, 1997;Liu et al, 2003) as well as reasonable climate variability (Wu and Liu, 2005). As HadCM3BL, FOAM exhibits a cold high-latitude bias in the Northern Hemisphere, in particular in winter (Gallimore et al, 2005).…”

Section: Model Simulationssupporting

confidence: 62%

“…These models are all relatively low resolution and less complex than some others that have been used in recent studies (e.g. Hutchinson et al, 2018;Baatsen et al, 2018); however, they are still regularly used in palaeoclimate research (e.g. Goddéris et al, 2017;Farnsworth et al, 2019;Saupe , 2019).…”

Section: Model Simulationsmentioning

confidence: 99%

“…By contrast, complex fully coupled climate models generally cannot be run for long (>10 4 years) transient simulations and instead often only provide equilibrium snapshots of climate at a single point in time but offer a complete spatial picture of how different regions compare to one another in a physically consistent way (e.g. Goldner et al, 2014;Lunt et al, 2016;Hutchinson et al, 2018).…”

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confidence: 99%

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Changes in the high-latitude Southern Hemisphere through the Eocene–Oligocene transition: a model–data comparison

et al. 2020

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The global and regional climate changed dramatically with the expansion of the Antarctic Ice Sheet at the Eocene-Oligocene transition (EOT). These large-scale changes are generally linked to declining atmospheric pCO 2 levels and/or changes in Southern Ocean gateways such as the Drake Passage around this time. To better understand the Southern Hemisphere regional climatic changes and the impact of glaciation on the Earth's oceans and atmosphere at the EOT, we compiled a database of 10 ocean and 4 landsurface temperature reconstructions from a range of proxy records and compared this with a series of fully coupled, low-resolution climate model simulations from two models (HadCM3BL and FOAM). Regional patterns in the proxy records of temperature show that cooling across the EOT was less at high latitudes and greater at mid-latitudes. While certain climate model simulations show moderate-good performance at recreating the temperature patterns shown in the data before and after the EOT, in general the model simulations do not capture the absolute latitudinal temperature gradient shown by the data, being too cold, particularly at high latitudes. When taking into account the absolute temperature before and after the EOT, as well as the change in temperature across it, simulations with a closed Drake Passage before and after the EOT or with an opening of the Drake Passage across the EOT perform poorly, whereas simulations with a drop in atmospheric pCO 2 in combination with ice growth generally perform better. This provides further sup-port for previous research that changes in atmospheric pCO 2 are more likely to have been the driver of the EOT climatic changes, as opposed to the opening of the Drake Passage.www.clim-past.net/16/555/2020/

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“…Hutchinson et al (2018Hutchinson et al ( , 2019. The ocean component uses the modular ocean model (MOM) version 5.1.0, while the other components of the model are the same as in CM2.1; Atmosphere Model 2, Land Model 2 and the Sea Ice Simulator 1.…”

mentioning

confidence: 99%

DeepMIP: Model intercomparison of early Eocene climatic optimum (EECO) large-scale climate features and comparison with proxy data

Lunt¹,

Bragg²,

Chan³

et al. 2020

Preprint

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Abstract. We present results from an ensemble of seven climate models, each of which has carried out simulations of the early Eocene climate optimum (EECO, ~ 50 million years ago). These simulations have been carried out in the framework of DeepMIP (www.deepmip.org), and as such all models have been configured with identical paleogeographic and vegetation boundary conditions. The results indicate that these non-CO2 boundary conditions contribute between 3 and 5 °C to Eocene warmth. Compared to results from previous studies, the DeepMIP simulations show reduced spread of global mean surface temperature response across the ensemble, for a given atmospheric CO2 concentration. In a marked departure from the results from previous simulations, at least two of the DeepMIP models (CESM and GFDL) are consistent with proxy indicators of global mean temperature, and atmospheric CO2, and meridional SST gradients. The best agreement with global SST proxies from these models occurs at CO2 concentrations of around 2400 ppmv. At a more regional scale the models lack skill in reproducing the proxy SSTs, in particular in the southwest Pacific, around New Zealand and south Australia, where the modelled anomalies are substantially less than indicated by the proxies. However, in these regions modelled continental surface air temperature anomalies are consistent with surface air temperature proxies, implying an inconsistency between marine and terrestrial temperatures in either the proxies or models in this region. Our aim is that the documentation of the large scale features and model-data comparison presented herein will pave the way to further studies that explore aspects of the model simulations in more detail, for example the ocean circulation, hydrological cycle, and modes of variability; and encourage sensitivity studies to aspects such as paleogeography and aerosols.

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Climate sensitivity and meridional overturning circulation in the late Eocene using GFDL CM2.1

Cited by 63 publications

References 104 publications

Assessing Mechanisms and Uncertainty in Modeled Climatic Change at the Eocene‐Oligocene Transition

Assessing Mechanisms and Uncertainty in Modeled Climatic Change at the Eocene‐Oligocene Transition

Changes in the high-latitude Southern Hemisphere through the Eocene–Oligocene transition: a model–data comparison

DeepMIP: Model intercomparison of early Eocene climatic optimum (EECO) large-scale climate features and comparison with proxy data

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