scholarly journals The Zero Emission Commitment Model Intercomparison Project (ZECMIP) contribution to CMIP6: Quantifying committed climate changes following zero carbon emissions

2019 ◽  
Author(s):  
Chris D. Jones ◽  
Thomas L. Frölicher ◽  
Charles Koven ◽  
Andrew H. MacDougall ◽  
H. Damon Matthews ◽  
...  
Keyword(s):  
Co2 Emissions ◽  
Temperature Change ◽  
General Circulation ◽  
Carbon Budget ◽  
Quantitative Information ◽  
Earth System ◽  
Model Intercomparison ◽  
System Models ◽  
Intercomparison Project ◽  
Earth System Models

Abstract. The amount of additional future temperature change following a complete cessation of CO2 emissions is a measure of the unrealized warming to which we are committed due to CO2 already emitted to the atmosphere. This "Zero Emissions Commitment" (ZEC) is also an important quantity when estimating the remaining carbon budget – a limit on the total amount of CO2 emissions consistent with limiting global mean temperature at a particular level. In the recent IPCC Special Report on Global Warming of 1.5 °C, the carbon budget framework used to calculate the remaining carbon budget for 1.5 °C included the assumption that the ZEC due to CO2 emissions is negligible and close to zero. Previous research has shown significant uncertainty even in the sign of the ZEC. To close this knowledge gap, we propose the Zero Emissions Commitment Model Intercomparison Project (ZECMIP), which will quantify the amount of unrealized temperature change that occurs after CO2 emissions cease and investigate the geophysical drivers behind this climate response. Quantitative information on ZEC is a key gap in our knowledge, and one that will not be addressed by currently planned CMIP6 simulations, yet it is crucial for verifying whether carbon budgets need to be adjusted to account for any unrealized temperature change resulting from past CO2 emissions. We request only one top priority simulation from comprehensive general circulation Earth System Models (ESMs) and Earth System Models of Intermediate Complexity (EMICs) – a branch from the 1 % CO2 run with CO2 emissions set to zero at the point of 1000 PgC of total CO2 emissions in the simulation – with the possibility for additional simulations, if resources allow. ZECMIP is part of CMIP6, under joint sponsorship by C4MIP and CDRMIP, with associated experiment names to enable data submissions to Earth System Grid Federation. All data will be published and made freely available.

scholarly journals The Zero Emissions Commitment Model Intercomparison Project (ZECMIP) contribution to C4MIP: quantifying committed climate changes following zero carbon emissions

2019 ◽  
Vol 12 (10) ◽  
pp. 4375-4385 ◽  
Author(s):  
Chris D. Jones ◽  
Thomas L. Frölicher ◽  
Charles Koven ◽  
Andrew H. MacDougall ◽  
H. Damon Matthews ◽  
...  
Keyword(s):  
Co2 Emissions ◽  
Temperature Change ◽  
General Circulation ◽  
Carbon Budget ◽  
Quantitative Information ◽  
Earth System ◽  
Model Intercomparison ◽  
System Models ◽  
Intercomparison Project ◽  
Earth System Models

Abstract. The amount of additional future temperature change following a complete cessation of CO2 emissions is a measure of the unrealized warming to which we are committed due to CO2 already emitted to the atmosphere. This “zero emissions commitment” (ZEC) is also an important quantity when estimating the remaining carbon budget – a limit on the total amount of CO2 emissions consistent with limiting global mean temperature at a particular level. In the recent IPCC Special Report on Global Warming of 1.5 ∘C, the carbon budget framework used to calculate the remaining carbon budget for 1.5 ∘C included the assumption that the ZEC due to CO2 emissions is negligible and close to zero. Previous research has shown significant uncertainty even in the sign of the ZEC. To close this knowledge gap, we propose the Zero Emissions Commitment Model Intercomparison Project (ZECMIP), which will quantify the amount of unrealized temperature change that occurs after CO2 emissions cease and investigate the geophysical drivers behind this climate response. Quantitative information on ZEC is a key gap in our knowledge, and one that will not be addressed by currently planned CMIP6 simulations, yet it is crucial for verifying whether carbon budgets need to be adjusted to account for any unrealized temperature change resulting from past CO2 emissions. We request only one top-priority simulation from comprehensive general circulation Earth system models (ESMs) and Earth system models of intermediate complexity (EMICs) – a branch from the 1 % CO2 run with CO2 emissions set to zero at the point of 1000 PgC of total CO2 emissions in the simulation – with the possibility for additional simulations, if resources allow. ZECMIP is part of CMIP6, under joint sponsorship by C4MIP and CDRMIP, with associated experiment names to enable data submissions to the Earth System Grid Federation. All data will be published and made freely available.

scholarly journals How Should a Global Carbon Budget be Estimated?

2021 ◽  
Author(s):  
Paul Clements
Keyword(s):  
Global Warming ◽  
Co2 Emissions ◽  
Carbon Budget ◽  
Arctic Sea Ice ◽  
Atmospheric Co2 ◽  
Earth System ◽  
Intergovernmental Panel ◽  
System Models ◽  
Climate Analysis ◽  
Earth System Models

Abstract The Intergovernmental Panel on Climate Change (IPCC), the authority for estimating a carbon budget for keeping to the Paris Agreement’s 1.5—2°C target for limiting global warming, has indicated a budget of 580—1170 gigatons (Gt) of carbon dioxide (CO2) from 2018. This budget is based largely on Earth system models using data from the instrumental record over the industrial period. During the prior 800,000 years, however, a range of 120 parts per million (ppm) in atmospheric CO2 was associated with about a 6°C change in temperature, while temperature has only risen about 1°C with the 130 ppm increase in atmospheric CO2 in the industrial period. The paleoclimate record indicates that the anthropogenic increase in CO2 up to the present commits Earth to significant additional warming, such as from reduced albedo as Arctic sea ice melts and further CO2 release from vegetative stores. Instrumental data and model updates also indicate greater warming from these sources than IPCC models predict. Additionally, reductions in CO2 emissions to meet the Paris warming target will also reduce cooling from aerosols, which the IPCC may also have underestimated. Together, these factors indicate that CO2 emissions consistent with the IPCC’s carbon budget are likely to lead to at least 2—2.5°C global warming. I draw on the sustained critique of IPCC findings by Hansen and his colleagues, who have argued that the paleoclimate should be considered on par with Earth system models in climate analysis, and for more ambitious targets for reducing CO2 emissions.

scholarly journals Estimated effect of the permafrost carbon feedback on the zero emissions commitment to climate change

2021 ◽  
Author(s):  
Andrew Hugh MacDougall
Keyword(s):  
Climate Change ◽  
Carbon Cycle ◽  
Co2 Emissions ◽  
System Model ◽  
Earth System ◽  
Model Intercomparison ◽  
Lag Effect ◽  
Intercomparison Project ◽  
Potential Impact ◽  
Earth System Models

Abstract. Zero Emissions Commitment (ZEC), the expected change in global temperature following the cessation of CO2 emissions has recently been assessed by the Zero Emissions Commitment Model Intercomparison Project (ZECMIP). ZECMIP concluded that the component of ZEC from CO2 emissions will likely be close to zero in the decades following the cessation of emissions. However, of the 18 Earth system models that participated in ZECMIP only two included a representation of the permafrost carbon feedback to climate change. To better assess the potential impact of permafrost carbon decay on ZEC a series of perturbed parameter experiments are here conducted with an Earth system model of intermediate complexity. The experiment suggest that the permafrost carbon cycle feedback will directly add 0.06 [0.02 to 0.14] °C to the benchmark ZEC value assesses 50 years after 1000 PgC of CO2 has been emitted to the atmosphere. An additional 0.04 [0 to 0.06] °C is likely to been added relative to the benchmark ZEC value from the thaw-lag effect unaccounted for in the ZECMIP experiment design. Overall we assess that the permafrost carbon feedback is unlikely to change the assessment that ZEC is close to zero on decadal timescales, however the feedback is expected to become more important over the coming centuries.

scholarly journals Assessment of malaria transmission changes in Africa, due to the climate impact of land use change using Coupled Model Intercomparison Project Phase 5 earth system models

2016 ◽  
Vol 11 (1s) ◽  
Author(s):  
Adrian M. Tompkins ◽  
Luca Caporaso
Keyword(s):  
Land Use ◽  
Land Use Change ◽  
Malaria Transmission ◽  
Earth System ◽  
Model Intercomparison ◽  
System Models ◽  
Intercomparison Project ◽  
Sahel Region ◽  
The Impact ◽  
Earth System Models

Using mathematical modelling tools, we assessed the potential for land use change (LUC) associated with the Intergovernmental Panel on Climate Change low- and high-end emission scenarios (RCP2.6 and RCP8.5) to impact malaria transmission in Africa. To drive a spatially explicit, dynamical malaria model, data from the four available earth system models (ESMs) that contributed to the LUC experiment of the Fifth Climate Model Intercomparison Project are used. Despite the limited size of the ESM ensemble, stark differences in the assessment of how LUC can impact climate are revealed. In three out of four ESMs, the impact of LUC on precipitation and temperature over the next century is limited, resulting in no significant change in malaria transmission. However, in one ESM, LUC leads to increases in precipitation under scenario RCP2.6, and increases in temperature in areas of land use conversion to farmland under both scenarios. The result is a more intense transmission and longer transmission seasons in the southeast of the continent, most notably in Mozambique and southern Tanzania. In contrast, warming associated with LUC in the Sahel region reduces risk in this model, as temperatures are already above the 25-30°C threshold at which transmission peaks. The differences between the ESMs emphasise the uncertainty in such assessments. It is also recalled that the modelling framework is unable to adequately represent local-scale changes in climate due to LUC, which some field studies indicate could be significant.

scholarly journals Estimated effect of the permafrost carbon feedback on the zero emissions commitment to climate change

2021 ◽  
Vol 18 (17) ◽  
pp. 4937-4952
Author(s):  
Andrew H. MacDougall
Keyword(s):  
Climate Change ◽  
Carbon Cycle ◽  
Co2 Emissions ◽  
System Model ◽  
Earth System ◽  
Model Intercomparison ◽  
Lag Effect ◽  
Intercomparison Project ◽  
Potential Impact ◽  
Earth System Models

Abstract. Zero Emissions Commitment (ZEC), the expected change in global temperature following the cessation of anthropogenic greenhouse gas emissions, has recently been assessed by the Zero Emissions Commitment Model Intercomparison Project (ZECMIP). ZECMIP concluded that the component of ZEC from CO2 emissions will likely be close to zero in the decades following the cessation of emissions. However, of the 18 Earth system models that participated in ZECMIP only 2 included a representation of the permafrost carbon feedback to climate change. To better assess the potential impact of permafrost carbon decay on ZEC, a series of perturbed parameter experiments are here conducted with an Earth system model of intermediate complexity. The experiment suggests that the permafrost carbon cycle feedback will directly add 0.06 [0.02 to 0.14] ∘C to the benchmark the ZEC value assesses 50 years after 1000 Pg C of CO2 has been emitted to the atmosphere. An additional 0.04 [0 to 0.06] ∘C is likely to been added relative to the benchmark ZEC value from the thaw-lag effect unaccounted for in the ZECMIP experiment design. Overall I assess that the permafrost carbon feedback is unlikely to change the assessment that ZEC is close to zero on decadal timescales; however, the feedback is expected to become more important over the coming centuries.

A stationary tropospheric sulphur cycle for Earth system models of intermediate complexit

2021 ◽  
Author(s):  
Alexey V. Eliseev ◽  
Rustam D. Gizatullin ◽  
Alexandr V. Timazhev
Keyword(s):  
Atmospheric Chemistry ◽  
Sulphur Dioxide ◽  
Wet Deposition ◽  
Earth System ◽  
Sulphur Compounds ◽  
Coupled Models ◽  
System Models ◽  
Sulphur Cycle ◽  
Intercomparison Project ◽  
Earth System Models

<p>A stationary, computationally efficient  scheme, ChAP-1.0 (Chemistry and Aerosol Processes, version 1.0) for the sulphur cycle in the troposphereis developed. This scheme is envisaged to be implemented into Earth system models of intermediate complexity (EMICs). The scheme accounts for sulphur dioxide emissions into the atmosphere, its deposition to the surface, oxidation to sulphates, and dry and wet deposition of sulphates on the surface.<br>The calculations with the scheme were performed with the anthropogenic emissions of sulphur compounds into the atmosphere for 1850-2000 according to the CMIP5 (Coupled Models Intercomparison Project, phase 5) 'historical' protocol, with the ERA-Interim meteorology, and assuming that natural sources of sulphur into the atmosphere remain unchanged during this period. The model reasonably reproduces characteristics of the tropospheric sulphur cycle known from observations and other simulations (e.g., in the Atmospheric Chemistry and Climate Model Intercomparison Project phase II (ACCMIP) simulations, Copernicus Atmosphere Monitoring Service (CAMS) reanalysis, and the Meteorological Synthesizing Centre–West of the European Monitoring and Evaluation Programme (EMEP MSC-W) data). In particular, in 1980's and 1990's, , when the global anthropogenic emission of sulphur, global atmospheric burdens of SO<sub>2</sub> and SO<sub>4</sub> account, correspondingly, 0.2 TgS and 0.4 TgS. In our scheme, about half of the emitted sulphur dioxide is deposited to the surface and the rest in oxidised into sulphates. The latter mostly removed from the atmosphere by wet deposition. The lifetime of the SO<sub>2</sub> and SO<sub>4</sub> in the atmosphere is, respectively, 1.0±0.1 days and 4.1±0.3 days.<br>Despite its simplicity, our scheme may be successfully used to simulate sulphur/sulphates pollution in the atmosphere at coarse spatial and time scales and an impact of this pollution to direct radiative effect of sulphates on climate, their respective indirect (cloud- and precipitation-related) effects, as well as an impact of sulphur compounds on the terrestrial carbon cycle.</p>

scholarly journals Inconsistent strategies to spin up models in CMIP5: implications for ocean biogeochemical model performance assessment

2016 ◽  
Vol 9 (5) ◽  
pp. 1827-1851 ◽  
Author(s):  
Roland Séférian ◽  
Marion Gehlen ◽  
Laurent Bopp ◽  
Laure Resplandy ◽  
James C. Orr ◽  
...  
Keyword(s):  
Performance Assessment ◽  
Initial Conditions ◽  
Model Performance ◽  
Cmip5 Models ◽  
Biogeochemical Model ◽  
Earth System ◽  
Model Intercomparison ◽  
System Models ◽  
Marine Biogeochemistry ◽  
Earth System Models

Abstract. During the fifth phase of the Coupled Model Intercomparison Project (CMIP5) substantial efforts were made to systematically assess the skill of Earth system models. One goal was to check how realistically representative marine biogeochemical tracer distributions could be reproduced by models. In routine assessments model historical hindcasts were compared with available modern biogeochemical observations. However, these assessments considered neither how close modeled biogeochemical reservoirs were to equilibrium nor the sensitivity of model performance to initial conditions or to the spin-up protocols. Here, we explore how the large diversity in spin-up protocols used for marine biogeochemistry in CMIP5 Earth system models (ESMs) contributes to model-to-model differences in the simulated fields. We take advantage of a 500-year spin-up simulation of IPSL-CM5A-LR to quantify the influence of the spin-up protocol on model ability to reproduce relevant data fields. Amplification of biases in selected biogeochemical fields (O2, NO3, Alk-DIC) is assessed as a function of spin-up duration. We demonstrate that a relationship between spin-up duration and assessment metrics emerges from our model results and holds when confronted with a larger ensemble of CMIP5 models. This shows that drift has implications for performance assessment in addition to possibly aliasing estimates of climate change impact. Our study suggests that differences in spin-up protocols could explain a substantial part of model disparities, constituting a source of model-to-model uncertainty. This requires more attention in future model intercomparison exercises in order to provide quantitatively more correct ESM results on marine biogeochemistry and carbon cycle feedbacks.

Response of tropical rainfall to reduced evapotranspiration depends on continental extent

2021 ◽  
pp. 1-50
Author(s):  
Marianne Pietschnig ◽  
Abigail L. S. Swann ◽  
F. Hugo Lambert ◽  
Geoffrey K. Vallis
Keyword(s):  
Stomatal Conductance ◽  
General Circulation ◽  
Amazon Basin ◽  
Circulation Model ◽  
Complex Model ◽  
Earth System ◽  
Area Index ◽  
Tropical Rainfall ◽  
System Models ◽  
Earth System Models

AbstractFuture projections of precipitation change over tropical land are often enhanced by vegetation responses to CO2 forcing in Earth System Models. Projected decreases in rainfall over the Amazon basin and increases over the Maritime Continent are both stronger when plant physiological changes are modelled than if these changes are neglected, but the reasons for this amplification remain unclear. The responses of vegetation to increasing CO2 levels are complex and uncertain, including possible decreases in stomatal conductance and increases in leaf area index due to CO2-fertilisation. Our results from an idealised Atmospheric General Circulation Model show that the amplification of rainfall changes occurs even when we use a simplified vegetation parameterisation based solely on CO2-driven decreases in stomatal conductance, indicating that this mechanism plays a key role in complex model projections. Based on simulations with rectangular continentswe find that reducing terrestrial evaporation to zero with increasing CO2 notably leads to enhanced rainfall over a narrow island. Strong heating and ascent over the island trigger moisture advection from the surrounding ocean. In contrast, over larger continents rainfall depends on continental evaporation. Simulations with two rectangular continents representing South America and Africa reveal that the stronger decrease in rainfall over the Amazon basin seen in Earth System Models is due to a combination of local and remote effects, which are fundamentally connected to South America’s size and its location with respect to Africa. The response of tropical rainfall to changes in evapotranspiration is thus connected to size and configuration of the continents.

scholarly journals Tracking Improvement in Simulated Marine Biogeochemistry Between CMIP5 and CMIP6

2020 ◽  
Author(s):  
Roland Séférian ◽  
Sarah Berthet ◽  
Andrew Yool ◽  
Julien Palmiéri ◽  
Laurent Bopp ◽  
...  
Keyword(s):  
Coupled Model ◽  
Climate Feedback ◽  
Full Potential ◽  
Earth System ◽  
Current Generation ◽  
System Models ◽  
Biogeochemical Models ◽  
Marine Biogeochemistry ◽  
Intercomparison Project ◽  
Earth System Models

Abstract Purpose of Review The changes or updates in ocean biogeochemistry component have been mapped between CMIP5 and CMIP6 model versions, and an assessment made of how far these have led to improvements in the simulated mean state of marine biogeochemical models within the current generation of Earth system models (ESMs). Recent Findings The representation of marine biogeochemistry has progressed within the current generation of Earth system models. However, it remains difficult to identify which model updates are responsible for a given improvement. In addition, the full potential of marine biogeochemistry in terms of Earth system interactions and climate feedback remains poorly examined in the current generation of Earth system models. Summary Increasing availability of ocean biogeochemical data, as well as an improved understanding of the underlying processes, allows advances in the marine biogeochemical components of the current generation of ESMs. The present study scrutinizes the extent to which marine biogeochemistry components of ESMs have progressed between the 5th and the 6th phases of the Coupled Model Intercomparison Project (CMIP).

scholarly journals Modelling mid-Pliocene climate with COSMOS

2012 ◽  
Vol 5 (2) ◽  
pp. 917-966 ◽  
Author(s):  
C. Stepanek ◽  
G. Lohmann
Keyword(s):  
Air Temperature ◽  
Surface Air Temperature ◽  
Pi Control ◽  
Earth System ◽  
Model Intercomparison ◽  
Experimental Procedure ◽  
Intercomparison Project ◽  
Model Setup ◽  
Fully Coupled ◽  
Earth System Models

Abstract. In this manuscript we describe the experimental procedure employed at the Alfred Wegener Institute in Germany in the preparation of the simulations for the Pliocene Model Intercomparison Project (PlioMIP). We present a description of the utilized community earth system models (COSMOS) and document the procedures which we applied to transfer the Pliocene Research, Interpretation and Synoptic Mapping Project (PRISM) mid-Pliocene reconstruction into model forcing fields. The model setup and spin-up procedure are described for both the paleo and preindustrial (PI) time-slices of PlioMIP experiments 1 and 2, and general results that depict the performance of our model setup for mid-Pliocene conditions are presented. The mid-Pliocene as simulated with our COSMOS-setup and PRISM boundary conditions is both warmer and wetter than the PI. The globally averaged annual mean surface air temperature in the mid-Pliocene standalone atmosphere (fully coupled atmosphere-ocean) simulation is 17.35 °C (17.82 °C), which implies a warming of 2.23 °C (3.40 °C) relative to the respective PI control simulation.

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