scholarly journals State-Dependence of the Climate Sensitivity in Earth System Models of Intermediate Complexity

2017 ◽  
Vol 44 (20) ◽  
pp. 10,643-10,653 ◽  
Author(s):  
Patrik L. Pfister ◽  
Thomas F. Stocker
Keyword(s):  
Climate Sensitivity ◽  
State Dependence ◽  
Earth System ◽  
System Models ◽  
Intermediate Complexity ◽  
Earth System Models

scholarly journals Sensitivity of Global Warming to Carbon Emissions: Effects of Heat and Carbon Uptake in a Suite of Earth System Models

2017 ◽  
Vol 30 (23) ◽  
pp. 9343-9363 ◽  
Author(s):  
Richard G. Williams ◽  
Vassil Roussenov ◽  
Philip Goodwin ◽  
Laure Resplandy ◽  
Laurent Bopp
Keyword(s):  
Climate Sensitivity ◽  
Carbon Emissions ◽  
Radiative Forcing ◽  
Carbon Uptake ◽  
Earth System ◽  
Ocean Heat Uptake ◽  
Surface Warming ◽  
System Models ◽  
Heat Uptake ◽  
Earth System Models

Climate projections reveal global-mean surface warming increasing nearly linearly with cumulative carbon emissions. The sensitivity of surface warming to carbon emissions is interpreted in terms of a product of three terms: the dependence of surface warming on radiative forcing, the fractional radiative forcing from CO2, and the dependence of radiative forcing from CO2 on carbon emissions. Mechanistically each term varies, respectively, with climate sensitivity and ocean heat uptake, radiative forcing contributions, and ocean and terrestrial carbon uptake. The sensitivity of surface warming to fossil-fuel carbon emissions is examined using an ensemble of Earth system models, forced either by an annual increase in atmospheric CO2 or by RCPs until year 2100. The sensitivity of surface warming to carbon emissions is controlled by a temporal decrease in the dependence of radiative forcing from CO2 on carbon emissions, which is partly offset by a temporal increase in the dependence of surface warming on radiative forcing. The decrease in the dependence of radiative forcing from CO2 is due to a decline in the ratio of the global ocean carbon undersaturation to carbon emissions, while the increase in the dependence of surface warming is due to a decline in the ratio of ocean heat uptake to radiative forcing. At the present time, there are large intermodel differences in the sensitivity in surface warming to carbon emissions, which are mainly due to uncertainties in the climate sensitivity and ocean heat uptake. These uncertainties undermine the ability to predict how much carbon may be emitted before reaching a warming target.

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

2020 ◽  
Vol 6 (26) ◽  
pp. eaba1981 ◽  
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.

scholarly journals Atmospheric processing of iron in mineral and combustion aerosols: development of an intermediate-complexity mechanism suitable for Earth system models

2018 ◽  
Vol 18 (19) ◽  
pp. 14175-14196 ◽  
Author(s):  
Rachel A. Scanza ◽  
Douglas S. Hamilton ◽  
Carlos Perez Garcia-Pando ◽  
Clifton Buck ◽  
Alex Baker ◽  
...  
Keyword(s):  
Oxalic Acid ◽  
Earth System ◽  
Reference Case ◽  
Iron Solubility ◽  
Soluble Iron ◽  
System Models ◽  
Intermediate Complexity ◽  
Atmospheric Processing ◽  
Combustion Aerosols ◽  
Earth System Models

Abstract. Atmospheric processing of iron in dust and combustion aerosols is simulated using an intermediate-complexity soluble iron mechanism designed for Earth system models. The solubilization mechanism includes both a dependence on aerosol water pH and in-cloud oxalic acid. The simulations of size-resolved total, soluble and fractional iron solubility indicate that this mechanism captures many but not all of the features seen from cruise observations of labile iron. The primary objective was to determine the extent to which our solubility scheme could adequately match observations of fractional iron solubility. We define a semi-quantitative metric as the model mean at points with observations divided by the observational mean (MMO). The model is in reasonable agreement with observations of fractional iron solubility with an MMO of 0.86. Several sensitivity studies are performed to ascertain the degree of complexity needed to match observations; including the oxalic acid enhancement is necessary, while different parameterizations for calculating model oxalate concentrations are less important. The percent change in soluble iron deposition between the reference case (REF) and the simulation with acidic processing alone is 63.8 %, which is consistent with previous studies. Upon deposition to global oceans, global mean combustion iron solubility to total fractional iron solubility is 8.2 %; however, the contribution of fractional iron solubility from combustion sources to ocean basins below 15∘ S is approximately 50 %. We conclude that, in many remote ocean regions, sources of iron from combustion and dust aerosols are equally important. Our estimates of changes in deposition of soluble iron to the ocean since preindustrial climate conditions suggest roughly a doubling due to a combination of higher dust and combustion iron emissions along with more efficient atmospheric processing.

scholarly journals Earth system models of intermediate complexity: closing the gap in the spectrum of climate system models

2002 ◽  
Vol 18 (7) ◽  
pp. 579-586 ◽  
Author(s):  
Claussen M. ◽  
Mysak L. ◽  
Weaver A. ◽  
Crucifix M. ◽  
Fichefet T. ◽  
...  
Keyword(s):  
Climate System ◽  
Earth System ◽  
System Models ◽  
Intermediate Complexity ◽  
Closing The Gap ◽  
Earth System Models ◽  
Climate System Models

scholarly journals Biogeophysical effects of historical land cover changes simulated by six Earth system models of intermediate complexity

2006 ◽  
Vol 26 (6) ◽  
pp. 587-600 ◽  
Author(s):  
V. Brovkin ◽  
M. Claussen ◽  
E. Driesschaert ◽  
T. Fichefet ◽  
D. Kicklighter ◽  
...  
Keyword(s):  
Land Cover ◽  
Land Cover Changes ◽  
Earth System ◽  
System Models ◽  
Intermediate Complexity ◽  
Earth System Models

scholarly journals Atmospheric Processing of Iron in Mineral and Combustion Aerosols: Development of an Intermediate-Complexity Mechanism Suitable for Earth System Models

2018 ◽  
Author(s):  
Rachel A. Scanza ◽  
Natalie M. Mahowald ◽  
Carlos Perez Garcia-Pando ◽  
Clifton Buck ◽  
Alex Baker ◽  
...  
Keyword(s):  
Oxalic Acid ◽  
Earth System ◽  
Reference Case ◽  
Iron Solubility ◽  
Soluble Iron ◽  
System Models ◽  
Intermediate Complexity ◽  
Atmospheric Processing ◽  
Combustion Aerosols ◽  
Earth System Models

Abstract. Atmospheric processing of iron in dust and combustion aerosols is simulated using an intermediate-complexity soluble iron mechanism designed for Earth system models. The solubilization mechanism includes both a dependence on aerosol water pH and in-cloud oxalic acid. The simulations of size resolved total, soluble and fractional iron solubility indicate that this mechanism captures many but not all of the features seen from cruise observations of labile iron. The primary objective was to determine the extent to which our solubility scheme could adequately match observations of fractional iron solubility. We define a semi-quantitative metric as the model mean at points with observations divided by the observational mean (MMO); fractional iron solubility MMO is 0.8, indicating that while the model is not capturing all of the observational variability, it is within range of the observational mean. Several sensitivity studies are performed to ascertain the degree of complexity needed to match observations; including the oxalic acid enhancement is necessary while different parameterizations for calculating model oxalate concentrations are less important. The percent change in soluble iron deposition between the reference case and the simulation with acidic processing alone is 63.8 %, which is consistent with previous studies. Upon deposition to global oceans, global mean combustion iron solubility to total fractional iron solubility is 8.2 %; however, the contribution of fractional iron solubility from combustion sources to ocean basins below 15° S is approximately 50 %. We conclude that in many remote ocean regions, sources of iron from combustion and dust aerosols are equally important. Our estimates of changes in deposition of soluble iron to the ocean since preindustrial suggest roughly a doubling due to a combination of higher dust and combustion iron emissions along with more efficient atmospheric processing.

scholarly journals ChAP 1.0: A stationary tropospheric sulphur cycle for Earth system models of intermediate complexity

2021 ◽  
Author(s):  
Alexey V. Eliseev ◽  
Rustam D. Gizatullin ◽  
Alexandr V. Timazhev
Keyword(s):  
Sulphur Dioxide ◽  
Wet Deposition ◽  
Surface Oxidation ◽  
Earth System ◽  
Computationally Efficient ◽  
System Models ◽  
Intermediate Complexity ◽  
Sulphur Cycle ◽  
Efficient Scheme ◽  
Earth System Models

Abstract. A stationary, computationally efficient scheme ChAP-1.0 (Chemical and Aerosol Processes, version 1.0) for the sulphur cycle in the troposphere is developed. This scheme is designed for 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. The calculations with the scheme are performed forced by anthropogenic emissions of sulphur dioxide into the atmosphere for 1850–2000 adopted from the CMIP5 dataset and by the ERA-Interim meteorology assuming that natural sources of sulphur into the atmosphere remain unchanged during this period. The ChAP output is compared to changes of the tropospheric sulphur cycle simulations: with the CMIP5 data, with the IPCC TAR ensemble, and with the ACCMIP phase II simulations. In addition, in regions of strong anthropogenic sulphur pollution, ChAP results are compared to other data, such as the CAMS reanalysis, EMEP MSC-W, and with individual model simulations. Our model reasonably reproduces characteristics of the tropospheric sulphur cycle known from these information sources. In our scheme, about half of the emitted sulphur dioxide is deposited to the surface and the rest in oxidised into sulphates. In turn, sulphates are mostly removed from the atmosphere by wet deposition. The lifetime of the sulphur dioxide and sulphates in the atmosphere is close to 1 day and 5 days, respectively. The limitation of the scheme are acknowledged and the prospects for future development are figured out. Despite its simplicity, ChAP may be successfully used to simulate anthropogenic sulphur pollution in the atmosphere at coarse spatial and time scales.

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