What can Palaeoclimate Modelling do for you?

Haywood, Alan M.; Valdes, Paul J.; Aze, Tracy; Barlow, Natasha; Burke, Ariane; Dolan, Aisling M.; Heydt, Anna S. von der; Hill, Daniel J.; Jamieson, Stewart S. R.; Otto‐Bliesner, Bette L.; Salzmann, Ulrich; Saupe, Erin E.; Voß, Jochen

doi:10.1007/s41748-019-00093-1

Cited by 62 publications

(38 citation statements)

References 137 publications

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“…Although numerous interdisciplinary studies can be triggered by efficient climate modelling at the frontier of geology, climatology and biology (see e.g. Haywood et al (2019) for a synthesis), the question of the stability of biases with radically different…”

Section: Discussionmentioning

confidence: 99%

IPSL-CM5A2. An Earth System Model designed for multi-millennial climate simulations

Sepulchre¹,

Caubel²,

Ladant³

et al. 2019

Preprint

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Abstract. Based on the CMIP5-generation previous IPSL earth system model, we designed a new version, IPSL-CM5A2, aiming at running multi-millennial simulations typical of deep-time paleoclimates studies. Three priorities were followed during the set-up of the model: (1) improving the overall model computing performance, (2) overcoming a persistent cold bias depicted in the previous model generation, and (3) making the model able to handle the specific continental configurations of the geological past. Technical developments have been performed on separate components and on the coupling system to speed up the whole coupled model. These developments include the integration of hybrid parallelization MPI-OpenMP in LMDz atmospheric component, the use of a new library to perform parallel asynchronous input/output by using computing cores as “IO servers”, the use of a parallel coupling library between the ocean and the atmospheric components. The model can now simulate ~100 years per day, opening new possibilities towards the production of multi-millennial simulations with a full earth system model. The tuning strategy employed to overcome a persistent cold bias is detailed. The confrontation of an historical simulation to climatological observations shows overall improved ocean meridional overturning circulation, marine productivity and latitudinal position of zonal wind patterns. We also present the numerous steps required to run the IPSL-CM5A2 for deep-time paleoclimates through a preliminary case-study for the Cretaceous. Namely, a specific work on the ocean model grid was required to run the model for specific continental configurations in which continents are relocated according to past paleogeographic reconstructions. By briefly discussing the spin-up of such a simulation, we elaborate on the requirements and challenges awaiting paleoclimate modelling in the next years, namely finding the best trade-off between the level of description of the processes and the computing cost on supercomputers.

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Section: Discussionmentioning

confidence: 99%

IPSL-CM5A2. An Earth System Model designed for multi-millennial climate simulations

Sepulchre¹,

Caubel²,

Ladant³

et al. 2019

Preprint

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“…The models are clearly unrivaled in their ability to simulate a broad range of large‐scale phenomena on seasonal to decadal time scales (Flato et al, 2013). However, the reliability of models to simulate climate variability on multidecadal and longer time scales requires additional evaluation (Haywood et al, 2019). Climate records derived from paleoenvironmental parameters facilitate the testing of models out of the “comfort zone of present‐day climate,” or, in other words, one application of paleoclimate is to validate state‐of‐the‐art coupled climate models for past time slices and past climate transitions.…”

Section: Introductionmentioning

confidence: 99%

Abrupt Climate and Weather Changes Across Time Scales

Lohmann

Butzin

Eissner

et al. 2020

Paleoceanog and Paleoclimatol

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The past provides evidence of abrupt climate shifts and changes in the frequency of climate and weather extremes. We explore the nonlinear response to orbital forcing and then consider climate millennial variability down to daily weather events. Orbital changes are translated into regional responses in temperature, where the precessional response is related to nonlinearities and seasonal biases in the system. We question regularities found in climate events by analyzing the distribution of interevent waiting times. Periodicities of about 900 and 1,150 yr are found in ice cores besides the prominent 1,500 yr cycle. However, the variability remains indistinguishable from a random process, suggesting that centennial-to-millennial variability is stochastic in nature. New numerical techniques are developed allowing for a high resolution in the dynamically relevant regions like coasts, major upwelling regions, and high latitudes. Using this model, we find a strong sensitivity of the Atlantic meridional overturning circulation depending on where the deglacial meltwater is injected into. Meltwater into the Mississippi and near Labrador hardly affect the large-scale ocean circulation, whereas subpolar hosing mimicking icebergs yields a quasi shutdown. The same multiscale approach is applied to radiocarbon simulations enabling a dynamical interpretation of marine sediment cores. Finally, abrupt climate events also have counterparts in the recent climate records, revealing a close link between climate variability, the statistics of North Atlantic weather patterns, and extreme events. Plain Language Summary Predicting the future spread of possible climates, the risk of climate extremes and the risk of rapid transitions is of high socioeconomic relevance. The past provides evidence of abrupt climate change and the frequency of extremes. This allows to separate anthropogenic signals from natural climate variability. Earth system models applied both to past and future scenarios will enhance our ability to detect regime shifts which are necessary to potentially predict climate extremes and transitions. We consider the response of the system to regular orbital forcing and then focus on shorter time scales down to weather. The appearance of precession is linked to nonlinear responses of the climate system to external orbital forcing. Furthermore, we find that centennial-to-millennial variability is stochastic in nature. We also discuss recent developments of climate models with superior resolution in typical retrieval regions of paleoclimate records, such as continental margins and coasts. Using this model, we find a strong sensitivity of the Atlantic meridional overturning circulation depending on where the deglacial meltwater is injected into. Meltwater into the Mississippi and near Labrador hardly affect the large-scale ocean circulation, whereas subpolar hosing related to icebergs yields a quasi shutdown. Our multiscale approach is applied to radiocarbon simulations enabling a dynamical interpretation of marine sediment cores....

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“…Despite good agreement in simulating modern and preindustrial (PI) climate, Earth system models (ESMs) diverge in predicting many fundamental aspects of future climate change, including the transient melting behavior of the Arctic sea ice (Stroeve et al, 2012), Arctic feedbacks (Pithan & Mauritsen, 2014), changes in equatorial Pacific sea surface temperature (SST) pattern (Coats & Karnauskas, 2017;Seager et al, 2019;Vecchi & Soden, 2007), and changes in subtropical precipitation (Collins et al, 2013), among many others. Paleo-observations can provide independent out-of-sample data to help constrain these uncertainties (Haywood et al, 2019). To this end, Pliocene Model Intercomparison Project (PlioMIP) (Haywood et al, 2010(Haywood et al, , 2015 and Pliocene Research, Interpretation and Synoptic Mapping Project (PRISM) (Dowsett et al, 2013(Dowsett et al, , 2010(Dowsett et al, , 2016 have been carried out with separate focuses on paleoclimate modeling and paleo-observational data synthesis.…”

Section: Introductionmentioning

confidence: 99%

Increased Climate Response and Earth System Sensitivity From CCSM4 to CESM2 in Mid‐Pliocene Simulations

Feng

Otto‐Bliesner

Brady

et al. 2020

J Adv Model Earth Syst

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Three new equilibrium mid‐Pliocene (MP) simulations are implemented with the Community Climate System Model version 4 (CCSM4) and Community Earth System Model versions 1.2 (CESM1.2) and 2 (CESM2). All simulations are carried out with the same boundary and forcing conditions following the protocol of Pliocene Model Intercomparison Project Phase 2 (PlioMIP2). These simulations reveal amplified MP climate change relative to the preindustrial going from CCSM4 to CESM2, seen in global and polar averages of surface warming, sea ice reduction in both the Arctic and the Antarctic, and weakened Hadley circulation. The enhanced global mean warming arises from enhanced Earth system sensitivity (ESS) to not only CO2 change but also changes in boundary conditions primarily from vegetation and ice sheets. ESS is amplified by up to 70% in CCSM4 and up to 100% in CESM1.2 and CESM2 relative to the equilibrium climate sensitivity of respective models. Simulations disagree on several climate metrics. Different from CCSM4, both CESM1.2 and CESM2 show reduction of cloud cover, and weakened Walker circulation accompanied by an El Niño‐like mean state of the tropical Pacific in MP simulations relative to the preindustrial. This El Niño‐like mean state is consistent with paleo‐observational sea surface temperatures, suggesting an improvement upon CCSM4. The performances of MP simulations are assessed with a new compilation of observational MP sea surface temperature. The model‐data comparison suggests that CCSM4 is not sensitivity enough to the MP forcings, but CESM2 is likely too sensitive, especially in the tropics.

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What can Palaeoclimate Modelling do for you?

Cited by 62 publications

References 137 publications

IPSL-CM5A2. An Earth System Model designed for multi-millennial climate simulations

IPSL-CM5A2. An Earth System Model designed for multi-millennial climate simulations

Abrupt Climate and Weather Changes Across Time Scales

Increased Climate Response and Earth System Sensitivity From CCSM4 to CESM2 in Mid‐Pliocene Simulations

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