Efficacy of Climate Forcings in PDRMIP Models

Richardson, T.; Forster, Piers M.; Smith, Christopher J.; Maycock, Amanda C.; Wood, Tom; Andrews, Timothy; Boucher, Oliviér; Faluvegi, Gregory; Fläschner, Dagmar; Hodnebrog, Øivind; Kasoar, Matthew; Kirkevåg, Alf; Lamarque, J.; Mülmenstädt, J.; Myhre, Gunnar; Olivié, Dirk; Portmann, R. W.; Samset, B. H.; Shawki, Dilshad; Shindell, D. T.; Stier, Philip; Takemura, Toshihiko; Voulgarakis, Apostolos; Watson-Parris, Duncan

doi:10.1029/2019jd030581

Cited by 82 publications

(144 citation statements)

References 104 publications

Supporting

Mentioning

131

Contrasting

Order By: Relevance

“…It is important to emphasise that our stratospheric adjustment is calculated in a different way to the usual RF method, which uses an offline radiative transfer method. It may therefore be the case that differences are due to a change in tropopause height in greenhouse-gas-driven experiments (Santer et al, 2003).…”

Section: Non-cloud Adjustmentsmentioning

confidence: 99%

Effective radiative forcing and adjustments in CMIP6 models

et al. 2020

Self Cite

View full text Add to dashboard Cite

Abstract. The effective radiative forcing, which includes the instantaneous forcing plus adjustments from the atmosphere and surface, has emerged as the key metric of evaluating human and natural influence on the climate. We evaluate effective radiative forcing and adjustments in 17 contemporary climate models that are participating in the Coupled Model Intercomparison Project (CMIP6) and have contributed to the Radiative Forcing Model Intercomparison Project (RFMIP). Present-day (2014) global-mean anthropogenic forcing relative to pre-industrial (1850) levels from climate models stands at 2.00 (±0.23) W m−2, comprised of 1.81 (±0.09) W m−2 from CO2, 1.08 (± 0.21) W m−2 from other well-mixed greenhouse gases, −1.01 (± 0.23) W m−2 from aerosols and −0.09 (±0.13) W m−2 from land use change. Quoted uncertainties are 1 standard deviation across model best estimates, and 90 % confidence in the reported forcings, due to internal variability, is typically within 0.1 W m−2. The majority of the remaining 0.21 W m−2 is likely to be from ozone. In most cases, the largest contributors to the spread in effective radiative forcing (ERF) is from the instantaneous radiative forcing (IRF) and from cloud responses, particularly aerosol–cloud interactions to aerosol forcing. As determined in previous studies, cancellation of tropospheric and surface adjustments means that the stratospherically adjusted radiative forcing is approximately equal to ERF for greenhouse gas forcing but not for aerosols, and consequentially, not for the anthropogenic total. The spread of aerosol forcing ranges from −0.63 to −1.37 W m−2, exhibiting a less negative mean and narrower range compared to 10 CMIP5 models. The spread in 4×CO2 forcing has also narrowed in CMIP6 compared to 13 CMIP5 models. Aerosol forcing is uncorrelated with climate sensitivity. Therefore, there is no evidence to suggest that the increasing spread in climate sensitivity in CMIP6 models, particularly related to high-sensitivity models, is a consequence of a stronger negative present-day aerosol forcing and little evidence that modelling groups are systematically tuning climate sensitivity or aerosol forcing to recreate observed historical warming.

show abstract

Section: Non-cloud Adjustmentsmentioning

confidence: 99%

Effective radiative forcing and adjustments in CMIP6 models

et al. 2020

Self Cite

View full text Add to dashboard Cite

show abstract

“…The ERF includes rapid adjustments due to changes in atmospheric temperature, water vapor, and clouds without any response from surface temperature changes 3,18,19 and goes beyond RF, which only includes the adjustment from stratospheric temperature 3 . ERF is the best measure to compare the global mean surface temperature change between different forcing mechanisms for perturbations to the Earth's radiation budget, and in particular when the effect of the small land surface warming is removed in climate simulations keeping sea surface temperature constant 20 .…”

Section: Introductionmentioning

confidence: 99%

Historical total ozone radiative forcing derived from CMIP6 simulations

et al. 2020

Self Cite

View full text Add to dashboard Cite

Radiative forcing (RF) time series for total ozone from 1850 up to the present day are calculated based on historical simulations of ozone from 10 climate models contributing to the Coupled Model Intercomparison Project Phase 6 (CMIP6). In addition, RF is calculated for ozone fields prepared as an input for CMIP6 models without chemistry schemes and from a chemical transport model simulation. A radiative kernel for ozone is constructed and used to derive the RF. The ozone RF in 2010 (2005-2014) relative to 1850 is 0.35 W m −2 [0.08-0.61] (5-95% uncertainty range) based on models with both tropospheric and stratospheric chemistry. One of these models has a negative present-day total ozone RF. Excluding this model, the present-day ozone RF increases to 0.39 W m −2 [0.27-0.51] (5-95% uncertainty range). The rest of the models have RF close to or stronger than the RF time series assessed by the Intergovernmental Panel on Climate Change in the fifth assessment report with the primary driver likely being the new precursor emissions used in CMIP6. The rapid adjustments beyond stratospheric temperature are estimated to be weak and thus the RF is a good measure of effective radiative forcing.

show abstract

“…This assumption is common when diagnosing RF in transient simulations (Gregory & Forster , 2008;Andrews et al, 2012). It is also supported by Richardson et al (2019), who use RF step change experiments for multiple forcing agents and find multimodel mean efficacies close to unity. They also find that the location of sulfate aerosol emissions does not change the efficacy.…”

Section: Geophysical Research Lettersmentioning

confidence: 74%

Decadal Attribution of Historic Temperature and Ocean Heat Content Change to Anthropogenic Emissions

Larson

Portmann

Solomon

et al. 2020

Geophysical Research Letters

Self Cite

View full text Add to dashboard Cite

We present an alternative method of calculating the historical effective radiative forcing using the observed temperature record and a kernel based on the 5th Climate Model Intercomparison Project (CMIP5) temperature response. This estimate is the effective radiative forcing time series that the average climate model would need to simulate the observed global mean surface temperature anomalies. We further infer the anthropogenic aerosols radiative forcing as a residual using the better‐known greenhouse gas radiative forcing. This allows an independent estimate of anthropogenic aerosol radiative forcing, which suggests a cooling influence due to aerosols in the early part of the twentieth century. The temporal kernels are also used to calculate decadal contributions from the dominant forcing agents to present‐day temperature, ocean heat content, and thermosteric sea level rise. The current global mean temperature anomaly is dominated by emissions in the past two decades, while current ocean heat content is more strongly affected by earlier decades.

show abstract

Efficacy of Climate Forcings in PDRMIP Models

Cited by 82 publications

References 104 publications

Effective radiative forcing and adjustments in CMIP6 models

Effective radiative forcing and adjustments in CMIP6 models

Historical total ozone radiative forcing derived from CMIP6 simulations

Decadal Attribution of Historic Temperature and Ocean Heat Content Change to Anthropogenic Emissions

Contact Info

Product

Resources

About