The HadGEM2-ES implementation of CMIP5 centennial simulations

Abstract. The scientific understanding of the Earth's climate system, including the central question of how the climate system is likely to respond to human-induced perturbations, is comprehensively captured in GCMs and Earth System Models(ESM). Diagnosing the simulated climate response, and comparing responses across different models, is crucially dependent on transparent assumptions of how the GCM/ESM has been driven – especially because the implementation can involve subjective decisions and may differ between modelling groups performing the same experiment. This paper outlines the climate forcings and setup of the Met Office Hadley Centre ESM, HadGEM2-ES for the CMIP5 set of centennial experiments. We document the prescribed greenhouse gas concentrations, aerosol precursors, stratospheric and tropospheric ozone assumptions, as well as implementation of land-use change and natural forcings for the HadGEM2-ES historical and future experiments following the Representative Concentration Pathways. In addition, we provide details of how HadGEM2-ES ensemble members were initialised from the control run and how the palaeoclimate and AMIP experiments, as well as the "emission-driven" RCP experiments were performed.

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The HadGEM2-ES implementation of CMIP5 centennial simulations

Geoscientific Model Development ◽

10.5194/gmd-4-543-2011 ◽

2011 ◽

Vol 4 (3) ◽

pp. 543-570 ◽

Cited By ~ 546

Author(s):

C. D. Jones ◽

J. K. Hughes ◽

N. Bellouin ◽

S. C. Hardiman ◽

G. S. Jones ◽

...

Keyword(s):

Tropospheric Ozone ◽

Climate System ◽

Climate Response ◽

Earth System ◽

Central Question ◽

Simulated Climate ◽

Climate Forcings ◽

Earth’S Climate ◽

Hadley Centre ◽

Earth System Models

Abstract. The scientific understanding of the Earth's climate system, including the central question of how the climate system is likely to respond to human-induced perturbations, is comprehensively captured in GCMs and Earth System Models (ESM). Diagnosing the simulated climate response, and comparing responses across different models, is crucially dependent on transparent assumptions of how the GCM/ESM has been driven – especially because the implementation can involve subjective decisions and may differ between modelling groups performing the same experiment. This paper outlines the climate forcings and setup of the Met Office Hadley Centre ESM, HadGEM2-ES for the CMIP5 set of centennial experiments. We document the prescribed greenhouse gas concentrations, aerosol precursors, stratospheric and tropospheric ozone assumptions, as well as implementation of land-use change and natural forcings for the HadGEM2-ES historical and future experiments following the Representative Concentration Pathways. In addition, we provide details of how HadGEM2-ES ensemble members were initialised from the control run and how the palaeoclimate and AMIP experiments, as well as the "emission-driven" RCP experiments were performed.

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ESD Reviews: Evidence of multiple inconsistencies between representations of terrestrial and marine ecosystems in Earth System Models

10.5194/esd-2020-55 ◽

2020 ◽

Author(s):

Félix Pellerin ◽

Philipp Porada ◽

Inga Hense

Keyword(s):

Marine Ecosystem ◽

Marine Ecosystems ◽

Climate System ◽

Biological Processes ◽

Earth System ◽

Climate Feedbacks ◽

Ecosystem Models ◽

System Models ◽

Marine Ecosystem Models ◽

Earth System Models

Abstract. Terrestrial and marine ecosystems interact with other Earth system components through different biosphere-climate feedbacks that are very similar among ecosystem types. Despite these similarities, terrestrial and marine systems are often treated relatively separately in Earth System Models (ESM). In these ESM, the ecosystems are represented by a set of biological processes that are able to influence the climate system by affecting the chemical and physical properties of the environment. While most of the climate-relevant processes are shared between ecosystem types, model representations of terrestrial and marine ecosystems often differ. This raises the question whether inconsistencies between terrestrial and marine ecosystem models exist and potentially skew our perception of the relative influence of each ecosystem on climate. Here we compared the terrestrial and marine modules of 17 Earth System Models in order to identify inconsistencies between the two ecosystem types. We sorted out the biological processes included in ESM regarding their influence on climate into three types of biosphere-climate feedbacks (i.e. the biogeochemical pumps, the biogeophysical mechanisms and the gas and particle shuttles), and critically compare their representation in the different ecosystem modules. Overall, we found multiple evidences of unjustified differences in process representations between terrestrial and marine ecosystem models within ESM. These inconsistencies may lead to wrong predictions about the role of biosphere in the climate system. We believe that the present comparison can be used by the Earth system modeling community to increase consistency between ecosystem models. We further call for the development of a common framework allowing the uniform representation of climate-relevant processes in ecosystem modules of ESM.

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Why Is Climate More Sensitive in the Latest Earth System Models?

Eos ◽

10.1029/2020eo141895 ◽

2020 ◽

Vol 101 ◽

Author(s):

David Shultz

Keyword(s):

Carbon Dioxide ◽

Earth System ◽

System Models ◽

Increased Sensitivity ◽

Earth’S Climate ◽

Earth System Models

Compared with previous generations, current Earth system models predict that Earth’s climate is more sensitive to carbon dioxide. Where does the increased sensitivity come from?

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Plant Physiology Increases the Magnitude and Spread of the Transient Climate Response to CO2 in CMIP6 Earth System Models

Journal of Climate ◽

10.1175/jcli-d-20-0078.1 ◽

2020 ◽

Vol 33 (19) ◽

pp. 8561-8578

Author(s):

Claire M. Zarakas ◽

Abigail L. S. Swann ◽

Marysa M. Laguë ◽

Kyle C. Armour ◽

James T. Randerson

Keyword(s):

Plant Physiology ◽

Coupled Model ◽

Surface Air Temperature ◽

Physiological Effect ◽

Climate Response ◽

Earth System ◽

Transient Climate Response ◽

Near Surface ◽

System Models ◽

Earth System Models

AbstractIncreasing concentrations of CO2 in the atmosphere influence climate both through CO2’s role as a greenhouse gas and through its impact on plants. Plants respond to atmospheric CO2 concentrations in several ways that can alter surface energy and water fluxes and thus surface climate, including changes in stomatal conductance, water use, and canopy leaf area. These plant physiological responses are already embedded in most Earth system models, and a robust literature demonstrates that they can affect global-scale temperature. However, the physiological contribution to transient warming has yet to be assessed systematically in Earth system models. Here this gap is addressed using carbon cycle simulations from phases 5 and 6 of the Coupled Model Intercomparison Project (CMIP) to isolate the radiative and physiological contributions to the transient climate response (TCR), which is defined as the change in globally averaged near-surface air temperature during the 20-yr window centered on the time of CO2 doubling relative to preindustrial CO2 concentrations. In CMIP6 models, the physiological effect contributes 0.12°C (σ: 0.09°C; range: 0.02°–0.29°C) of warming to the TCR, corresponding to 6.1% of the full TCR (σ: 3.8%; range: 1.4%–13.9%). Moreover, variation in the physiological contribution to the TCR across models contributes disproportionately more to the intermodel spread of TCR estimates than it does to the mean. The largest contribution of plant physiology to CO2-forced warming—and the intermodel spread in warming—occurs over land, especially in forested regions.

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Harmonising plant functional type distributions for evaluating Earth system models

Climate of the Past ◽

10.5194/cp-15-335-2019 ◽

2019 ◽

Vol 15 (1) ◽

pp. 335-366 ◽

Cited By ~ 10

Author(s):

Anne Dallmeyer ◽

Martin Claussen ◽

Victor Brovkin

Keyword(s):

Classical Method ◽

New Method ◽

Earth System ◽

System Models ◽

Warm Temperate Forest ◽

Simulated Climate ◽

Vegetation Models ◽

Global Vegetation ◽

Warm Temperate ◽

Earth System Models

Abstract. Dynamic vegetation models simulate global vegetation in terms of fractional coverage of a few plant functional types (PFTs). Although these models often share the same concept, they differ with respect to the number and kind of PFTs, complicating the comparability of simulated vegetation distributions. Pollen-based vegetation reconstructions are initially only available in the form of time series of individual taxa that are not distinguished in the models. Thus, to evaluate simulated vegetation distributions, the modelling results and pollen-based vegetation reconstructions have to be converted into a comparable format. The classical approach is the method of biomisation, but hitherto PFT-based biomisation methods were only available for individual models. We introduce and evaluate a simple, universally applicable technique to harmonise PFT distributions by assigning them into nine mega-biomes, using only assumptions on the minimum PFT cover fractions and few bioclimatic constraints (based on the 2 m temperature). These constraints mainly follow the limitation rules used in the classical biome models (here BIOME4). We test the method for six state-of-the-art dynamic vegetation models that are included in Earth system models based on pre-industrial, mid-Holocene and Last Glacial Maximum simulations. The method works well, independent of the spatial resolution or the complexity of the models. Large biome belts (such as tropical forest) are generally better represented than regionally confined biomes (warm–temperate forest, savanna). The comparison with biome distributions inferred via the classical biomisation approach of forcing biome models (here BIOME1) with the simulated climate states shows that the PFT-based biomisation is even able to keep up with the classical method. However, as the new method considers the PFT distributions actually calculated by the Earth system models, it allows for a direct comparison and evaluation of simulated vegetation distributions which the classical method cannot do. Thereby, the new method provides a powerful tool for the evaluation of Earth system models in general.

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Carbon–Concentration and Carbon–Climate Feedbacks in CMIP5 Earth System Models

Journal of Climate ◽

10.1175/jcli-d-12-00494.1 ◽

2013 ◽

Vol 26 (15) ◽

pp. 5289-5314 ◽

Cited By ~ 436

Author(s):

Vivek K. Arora ◽

George J. Boer ◽

Pierre Friedlingstein ◽

Michael Eby ◽

Chris D. Jones ◽

...

Keyword(s):

Carbon Concentration ◽

Coupled Model ◽

Co2 Flux ◽

Co2 Concentration ◽

Climate System ◽

Climate Feedback ◽

Earth System ◽

System Models ◽

Common Framework ◽

Earth System Models

Abstract The magnitude and evolution of parameters that characterize feedbacks in the coupled carbon–climate system are compared across nine Earth system models (ESMs). The analysis is based on results from biogeochemically, radiatively, and fully coupled simulations in which CO2 increases at a rate of 1% yr−1. These simulations are part of phase 5 of the Coupled Model Intercomparison Project (CMIP5). The CO2 fluxes between the atmosphere and underlying land and ocean respond to changes in atmospheric CO2 concentration and to changes in temperature and other climate variables. The carbon–concentration and carbon–climate feedback parameters characterize the response of the CO2 flux between the atmosphere and the underlying surface to these changes. Feedback parameters are calculated using two different approaches. The two approaches are equivalent and either may be used to calculate the contribution of the feedback terms to diagnosed cumulative emissions. The contribution of carbon–concentration feedback to diagnosed cumulative emissions that are consistent with the 1% increasing CO2 concentration scenario is about 4.5 times larger than the carbon–climate feedback. Differences in the modeled responses of the carbon budget to changes in CO2 and temperature are seen to be 3–4 times larger for the land components compared to the ocean components of participating models. The feedback parameters depend on the state of the system as well the forcing scenario but nevertheless provide insight into the behavior of the coupled carbon–climate system and a useful common framework for comparing models.

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Context for interpreting equilibrium climate sensitivity and transient climate response from the CMIP6 Earth system models

Science Advances ◽

10.1126/sciadv.aba1981 ◽

2020 ◽

Vol 6 (26) ◽

pp. eaba1981 ◽

Cited By ~ 21

Author(s):

Gerald A. Meehl ◽

Catherine A. Senior ◽

Veronika Eyring ◽

Gregory Flato ◽

Jean-Francois Lamarque ◽

...

Keyword(s):

Climate Sensitivity ◽

Coupled Model ◽

Cmip5 Models ◽

Climate Response ◽

Earth System ◽

Transient Climate Response ◽

Equilibrium Climate Sensitivity ◽

System Models ◽

Intercomparison Project ◽

Earth System Models

For the current generation of earth system models participating in the Coupled Model Intercomparison Project Phase 6 (CMIP6), the range of equilibrium climate sensitivity (ECS, a hypothetical value of global warming at equilibrium for a doubling of CO2) is 1.8°C to 5.6°C, the largest of any generation of models dating to the 1990s. Meanwhile, the range of transient climate response (TCR, the surface temperature warming around the time of CO2 doubling in a 1% per year CO2 increase simulation) for the CMIP6 models of 1.7°C (1.3°C to 3.0°C) is only slightly larger than for the CMIP3 and CMIP5 models. Here we review and synthesize the latest developments in ECS and TCR values in CMIP, compile possible reasons for the current values as supplied by the modeling groups, and highlight future directions. Cloud feedbacks and cloud-aerosol interactions are the most likely contributors to the high values and increased range of ECS in CMIP6.

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Overview of experiment design and comparison of models participating in phase 1 of the SPARC Quasi-Biennial Oscillation initiative (QBOi)

Geoscientific Model Development ◽

10.5194/gmd-11-1009-2018 ◽

2018 ◽

Vol 11 (3) ◽

pp. 1009-1032 ◽

Cited By ~ 37

Author(s):

Neal Butchart ◽

James A. Anstey ◽

Kevin Hamilton ◽

Scott Osprey ◽

Charles McLandress ◽

...

Keyword(s):

Experimental Design ◽

Numerical Experiments ◽

General Circulation ◽

Phase 1 ◽

Earth System ◽

Quasi Biennial Oscillation ◽

Climate Forcings ◽

Earth System Models ◽

Biennial Oscillation ◽

Stratospheric Variability

Abstract. The Stratosphere–troposphere Processes And their Role in Climate (SPARC) Quasi-Biennial Oscillation initiative (QBOi) aims to improve the fidelity of tropical stratospheric variability in general circulation and Earth system models by conducting coordinated numerical experiments and analysis. In the equatorial stratosphere, the QBO is the most conspicuous mode of variability. Five coordinated experiments have therefore been designed to (i) evaluate and compare the verisimilitude of modelled QBOs under present-day conditions, (ii) identify robustness (or alternatively the spread and uncertainty) in the simulated QBO response to commonly imposed changes in model climate forcings (e.g. a doubling of CO2 amounts), and (iii) examine model dependence of QBO predictability. This paper documents these experiments and the recommended output diagnostics. The rationale behind the experimental design and choice of diagnostics is presented. To facilitate scientific interpretation of the results in other planned QBOi studies, consistent descriptions of the models performing each experiment set are given, with those aspects particularly relevant for simulating the QBO tabulated for easy comparison.

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