scholarly journals Coupling earth system and integrated assessment models: the problem of steady state

2014 ◽  
Vol 7 (1) ◽  
pp. 1499-1524 ◽  
Author(s):  
B. Bond-Lamberty ◽  
K. Calvin ◽  
A. D. Jones ◽  
J. Mao ◽  
P. Patel ◽  
...  
Keyword(s):  
Land Use ◽  
Steady State ◽  
Integrated Assessment ◽  
Integrated Assessment Model ◽  
Assessment Model ◽  
System Model ◽  
Earth System ◽  
Short Term ◽  
Proxy Variables

Abstract. Human activities are significantly altering biogeochemical cycles at the global scale, posing a significant problem for earth system models (ESMs), which may incorporate static land-use change inputs but do not actively simulate policy or economic forces. One option to address this problem is to couple an ESM with an economically oriented integrated assessment model. Here we have implemented and tested a coupling mechanism between the carbon cycles of an ESM (CESM, the Community Earth System Model) and an integrated assessment (GCAM) model, examining the best proxy variables to share between the models, and quantifying our ability to distinguish climate- and land-use-driven flux changes. The net primary production and heterotrophic respiration outputs of the Community Land Model (CLM), the land component of CESM, were found to be the most robust proxy variables by which to manipulate GCAM's assumptions of long-term ecosystem steady state carbon, with short-term forest production strongly correlated with long-term biomass changes in climate-change model runs. Carbon-cycle effects of anthropogenic land-use change are short-term and spatially limited relative to widely distributed climate effects, and as a result we were able to distinguish these effects successfully in the model coupling, passing only the latter to GCAM. By allowing climate effects from a full earth system model to dynamically modulate the economic and policy decisions of an integrated assessment model, this work provides a foundation for linking these models in a robust and flexible framework capable of examining two-way interactions between human and earth system processes.

scholarly journals On linking an Earth system model to the equilibrium carbon representation of an economically optimizing land use model

2014 ◽  
Vol 7 (6) ◽  
pp. 2545-2555 ◽  
Author(s):  
B. Bond-Lamberty ◽  
K. Calvin ◽  
A. D. Jones ◽  
J. Mao ◽  
P. Patel ◽  
...  
Keyword(s):  
Land Use ◽  
Land Use Change ◽  
Carbon Cycle ◽  
Integrated Assessment ◽  
Integrated Assessment Model ◽  
Assessment Model ◽  
Earth System ◽  
Climate Effects ◽  
Community Land Model ◽  
Proxy Variables

Abstract. Human activities are significantly altering biogeochemical cycles at the global scale, and the scope of these activities will change with both future climate and socioeconomic decisions. This poses a significant challenge for Earth system models (ESMs), which can incorporate land use change as prescribed inputs but do not actively simulate the policy or economic forces that drive land use change. One option to address this problem is to couple an ESM with an economically oriented integrated assessment model, but this is challenging because of the radically different goals and underpinnings of each type of model. This study describes the development and testing of a coupling between the terrestrial carbon cycle of an ESM (CESM) and an integrated assessment (GCAM) model, focusing on how CESM climate effects on the carbon cycle could be shared with GCAM. We examine the best proxy variables to share between the models, and we quantify how carbon flux changes driven by climate, CO2 fertilization, and land use changes (e.g., deforestation) can be distinguished from each other by GCAM. The net primary production and heterotrophic respiration outputs of the Community Land Model (CLM), the land component of CESM, were found to be the most robust proxy variables by which to recalculate GCAM's assumptions of equilibrium ecosystem steady-state carbon. Carbon cycle effects of land use change are spatially limited relative to climate effects, and thus we were able to distinguish these effects successfully in the model coupling, passing only the latter to GCAM. This paper does not present results of a fully coupled simulation but shows, using a series of offline CLM simulations and an additional idealized Monte Carlo simulation, that our CESM–GCAM proxy variables reflect the phenomena that we intend and do not contain erroneous signals due to land use change. By allowing climate effects from a full ESM to dynamically modulate the economic and policy decisions of an integrated assessment model, this work will help link these models in a robust and flexible framework capable of examining two-way interactions between human and Earth system processes.

scholarly journals From land use to land cover: restoring the afforestation signal in a coupled integrated assessment–earth system model and the implications for CMIP5 RCP simulations

2014 ◽  
Vol 11 (22) ◽  
pp. 6435-6450 ◽  
Author(s):  
A. V. Di Vittorio ◽  
L. P. Chini ◽  
B. Bond-Lamberty ◽  
J. Mao ◽  
X. Shi ◽  
...  
Keyword(s):  
Land Use ◽  
Land Cover ◽  
Integrated Assessment ◽  
Coupled Model ◽  
Assessment Model ◽  
Carbon Gain ◽  
Climate Projections ◽  
Full Potential ◽  
Earth System ◽  
Intergovernmental Panel

Abstract. Climate projections depend on scenarios of fossil fuel emissions and land use change, and the Intergovernmental Panel on Climate Change (IPCC) AR5 parallel process assumes consistent climate scenarios across integrated assessment and earth system models (IAMs and ESMs). The CMIP5 (Coupled Model Intercomparison Project Phase 5) project used a novel "land use harmonization" based on the Global Land use Model (GLM) to provide ESMs with consistent 1500–2100 land use trajectories generated by historical data and four IAMs. A direct coupling of the Global Change Assessment Model (GCAM), GLM, and the Community ESM (CESM) has allowed us to characterize and partially address a major gap in the CMIP5 land coupling design: the lack of a corresponding land cover harmonization. For RCP4.5, CESM global afforestation is only 22% of GCAM's 2005 to 2100 afforestation. Likewise, only 17% of GCAM's 2040 afforestation, and zero pasture loss, were transmitted to CESM within the directly coupled model. This is a problem because GCAM relied on afforestation to achieve RCP4.5 climate stabilization. GLM modifications and sharing forest area between GCAM and GLM within the directly coupled model did not increase CESM afforestation. Modifying the land use translator in addition to GLM, however, enabled CESM to include 66% of GCAM's afforestation in 2040, and 94% of GCAM's pasture loss as grassland and shrubland losses. This additional afforestation increases CESM vegetation carbon gain by 19 PgC and decreases atmospheric CO2 gain by 8 ppmv from 2005 to 2040, which demonstrates that CESM without additional afforestation simulates a different RCP4.5 scenario than prescribed by GCAM. Similar land cover inconsistencies exist in other CMIP5 model results, primarily because land cover information is not shared between models. Further work to harmonize land cover among models will be required to increase fidelity between IAM scenarios and ESM simulations and realize the full potential of scenario-based earth system simulations.

scholarly journals OPTIMAL CLIMATE POLICY IN 3D: MITIGATION, CARBON REMOVAL, AND SOLAR GEOENGINEERING

2021 ◽  
pp. 2150008
Author(s):  
MARIIA BELAIA ◽  
JUAN B. MORENO-CRUZ ◽  
DAVID W. KEITH
Keyword(s):  
Climate Model ◽  
Integrated Assessment Model ◽  
Assessment Model ◽  
Short Term ◽  
Trade Offs ◽  
Solar Geoengineering ◽  
Optimal Climate Policy ◽  
The Cost ◽  
Far Future

We introduce solar geoengineering (SG) and carbon dioxide removal (CDR) into an integrated assessment model to analyze the trade-offs between mitigation, SG, and CDR. We propose a novel empirical parameterization of SG that disentangles its efficacy, calibrated with climate model results, from its direct impacts. We use a simple parameterization of CDR that decouples it from the scale of baseline emissions. We find that (a) SG optimally delays mitigation and lowers the use of CDR, which is distinct from moral hazard; (b) SG is deployed prior to CDR while CDR drives the phasing out of SG in the far future; (c) SG deployment in the short term is relatively independent of discounting and of the long-term trade-off between SG and CDR over time; (d) small amounts of SG sharply reduce the cost of meeting a [Formula: see text]C target and the costs of climate change, even with a conservative calibration for the efficacy of SG.

scholarly journals From land use to land cover: restoring the afforestation signal in a coupled integrated assessment – earth system model and the implications for CMIP5 RCP simulations

2014 ◽  
Vol 11 (5) ◽  
pp. 7151-7188 ◽  
Author(s):  
A. V. Di Vittorio ◽  
L. P. Chini ◽  
B. Bond-Lamberty ◽  
J. Mao ◽  
X. Shi ◽  
...  
Keyword(s):  
Land Use ◽  
Land Cover ◽  
Integrated Assessment ◽  
Coupled Model ◽  
Forest Growth ◽  
Assessment Model ◽  
Carbon Gain ◽  
Climate Projections ◽  
Earth System ◽  
Climate Scenarios

Abstract. Climate projections depend on scenarios of fossil fuel emissions and land use change, and the IPCC AR5 parallel process assumes consistent climate scenarios across Integrated Assessment and Earth System Models (IAMs and ESMs). The CMIP5 project used a novel "land use harmonization" based on the Global Land use Model (GLM) to provide ESMs with consistent 1500–2100 land use trajectories generated by historical data and four IAM projections. A direct coupling of the Global Change Assessment Model (GCAM), GLM, and the Community ESM (CESM) has allowed us to characterize and partially address a major gap in the CMIP5 land coupling design: the lack of a corresponding land cover harmonization. The CMIP5 CESM global afforestation is only 22% of GCAM's 2005 to 2100 RCP4.5 afforestation. Likewise, only 17% of GCAM's 2040 RCP4.5 afforestation, and zero pasture loss, were transmitted to CESM within the directly coupled model. This is a problem because afforestation was relied upon to achieve RCP4.5 climate stabilization. GLM modifications within the directly coupled model did not increase CESM afforestation. Modifying the land use translator in addition to GLM, however, enabled CESM to simulate 66% of GCAM's afforestation in 2040, and 94% of GCAM's pasture loss as grassland and shrubland losses. This additional afforestation increases vegetation carbon gain by 19 PgC and decreases atmospheric CO2 gain by 8 ppmv from 2005 to 2040, implying different RCP4.5 climate scenarios between CMIP5 GCAM and CESM. Although the IAMs and ESMs were not expected to have exactly the same climate forcing, due in part to different terrestrial carbon cycles and atmospheric radiation algorithms, the ESMs were expected to project climates representative of the RCP scenarios. Similar land cover inconsistencies exist in other CMIP5 model results, primarily because land cover information is not shared between models. High RCP4.5 afforestation might also contribute to inconsistencies as some ESMs might impose bioclimatic limits to potential forest area and have different rates of forest growth than projected by RCP4.5. Further work to harmonize land cover among models will be required to address this problem.

scholarly journals Greenhouse Gas Policy Influences Climate via Direct Effects of Land-Use Change

2013 ◽  
Vol 26 (11) ◽  
pp. 3657-3670 ◽  
Author(s):  
Andrew D. Jones ◽  
William D. Collins ◽  
James Edmonds ◽  
Margaret S. Torn ◽  
Anthony Janetos ◽  
...  
Keyword(s):  
Climate Change ◽  
Land Use ◽  
Land Use Change ◽  
Radiative Forcing ◽  
Climate Impacts ◽  
Earth System Model ◽  
Assessment Model ◽  
System Model ◽  
Earth System ◽  
Alternative Scenario

Abstract Proposed climate mitigation measures do not account for direct biophysical climate impacts of land-use change (LUC), nor do the stabilization targets modeled for phase 5 of the Coupled Model Intercomparison Project (CMIP5) representative concentration pathways (RCPs). To examine the significance of such effects on global and regional patterns of climate change, a baseline and an alternative scenario of future anthropogenic activity are simulated within the Integrated Earth System Model, which couples the Global Change Assessment Model, Global Land-Use Model, and Community Earth System Model. The alternative scenario has high biofuel utilization and approximately 50% less global forest cover than the baseline, standard RCP4.5 scenario. Both scenarios stabilize radiative forcing from atmospheric constituents at 4.5 W m−2 by 2100. Thus, differences between their climate predictions quantify the biophysical effects of LUC. Offline radiative transfer and land model simulations are also utilized to identify forcing and feedback mechanisms driving the coupled response. Boreal deforestation is found to strongly influence climate because of increased albedo coupled with a regional-scale water vapor feedback. Globally, the alternative scenario yields a twenty-first-century warming trend that is 0.5°C cooler than baseline, driven by a 1 W m−2 mean decrease in radiative forcing that is distributed unevenly around the globe. Some regions are cooler in the alternative scenario than in 2005. These results demonstrate that neither climate change nor actual radiative forcing is uniquely related to atmospheric forcing targets such as those found in the RCPs but rather depend on particulars of the socioeconomic pathways followed to meet each target.

scholarly journals Long-term deep decarbonisation pathways for Ecuador: Insights from an integrated assessment model

2021 ◽  
Vol 35 ◽  
pp. 100637
Author(s):  
Daniel Villamar ◽  
Rafael Soria ◽  
Pedro Rochedo ◽  
Alexandre Szklo ◽  
Mariana Imperio ◽  
...  
Keyword(s):  
Integrated Assessment ◽  
Integrated Assessment Model ◽  
Assessment Model

scholarly journals The integrated Earth system model version 1: formulation and functionality

2015 ◽  
Vol 8 (7) ◽  
pp. 2203-2219 ◽  
Author(s):  
W. D. Collins ◽  
A. P. Craig ◽  
J. E. Truesdale ◽  
A. V. Di Vittorio ◽  
A. D. Jones ◽  
...  
Keyword(s):  
Global Climate ◽  
Earth System Model ◽  
Climate System ◽  
Integrated Assessment Model ◽  
Assessment Model ◽  
System Model ◽  
Earth System ◽  
Natural Systems ◽  
Potential Applications ◽  
Induced Changes

Abstract. The integrated Earth system model (iESM) has been developed as a new tool for projecting the joint human/climate system. The iESM is based upon coupling an integrated assessment model (IAM) and an Earth system model (ESM) into a common modeling infrastructure. IAMs are the primary tool for describing the human–Earth system, including the sources of global greenhouse gases (GHGs) and short-lived species (SLS), land use and land cover change (LULCC), and other resource-related drivers of anthropogenic climate change. ESMs are the primary scientific tools for examining the physical, chemical, and biogeochemical impacts of human-induced changes to the climate system. The iESM project integrates the economic and human-dimension modeling of an IAM and a fully coupled ESM within a single simulation system while maintaining the separability of each model if needed. Both IAM and ESM codes are developed and used by large communities and have been extensively applied in recent national and international climate assessments. By introducing heretofore-omitted feedbacks between natural and societal drivers, we can improve scientific understanding of the human–Earth system dynamics. Potential applications include studies of the interactions and feedbacks leading to the timing, scale, and geographic distribution of emissions trajectories and other human influences, corresponding climate effects, and the subsequent impacts of a changing climate on human and natural systems. This paper describes the formulation, requirements, implementation, testing, and resulting functionality of the first version of the iESM released to the global climate community.

scholarly journals The integrated Earth System Model (iESM): formulation and functionality

2015 ◽  
Vol 8 (1) ◽  
pp. 381-427 ◽  
Author(s):  
W. D. Collins ◽  
A. P. Craig ◽  
J. E. Truesdale ◽  
A. V. Di Vittorio ◽  
A. D. Jones ◽  
...  
Keyword(s):  
Global Climate ◽  
Earth System Model ◽  
Climate System ◽  
Integrated Assessment Model ◽  
Assessment Model ◽  
System Model ◽  
Earth System ◽  
Natural Systems ◽  
Potential Applications ◽  
Induced Changes

Abstract. The integrated Earth System Model (iESM) has been developed as a new tool for projecting the joint human/climate system. The iESM is based upon coupling an Integrated Assessment Model (IAM) and an Earth System Model (ESM) into a common modeling infrastructure. IAMs are the primary tool for describing the human–Earth system, including the sources of global greenhouse gases (GHGs) and short-lived species, land use and land cover change, and other resource-related drivers of anthropogenic climate change. ESMs are the primary scientific tools for examining the physical, chemical, and biogeochemical impacts of human-induced changes to the climate system. The iESM project integrates the economic and human dimension modeling of an IAM and a fully coupled ESM within a single simulation system while maintaining the separability of each model if needed. Both IAM and ESM codes are developed and used by large communities and have been extensively applied in recent national and international climate assessments. By introducing heretofore-omitted feedbacks between natural and societal drivers, we can improve scientific understanding of the human–Earth system dynamics. Potential applications include studies of the interactions and feedbacks leading to the timing, scale, and geographic distribution of emissions trajectories and other human influences, corresponding climate effects, and the subsequent impacts of a changing climate on human and natural systems. This paper describes the formulation, requirements, implementation, testing, and resulting functionality of the first version of the iESM released to the global climate community.

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