Isolating the Evolving Contributions of Anthropogenic Aerosols and Greenhouse Gases: A New CESM1 Large Ensemble Community Resource

The evolving roles of anthropogenic aerosols (AER) and greenhouse gases (GHG) in driving large-scale patterns of precipitation and SST trends during 1920–2080 are studied using a new set of “all-but-one-forcing” initial-condition large ensembles (LEs) with the Community Earth System Model version 1 (CESM1), which complement the original “all-forcing” CESM1 LE (ALL). The large number of ensemble members (15–20) in each of the new LEs enables regional impacts of AER and GHG to be isolated from the noise of the model’s internal variability. Our analysis approach, based on running 50-yr trends, accommodates geographical and temporal changes in patterns of forcing and response. AER are shown to be the primary driver of large-scale patterns of externally forced trends in ALL before the late 1970s, and GHG to dominate thereafter. The AER and GHG forced trends are spatially distinct except during the 1970s transition phase when aerosol changes are mainly confined to lower latitudes. The transition phase is also characterized by a relative minimum in the amplitude of forced trend patterns in ALL, due to a combination of reduced AER and partially offsetting effects of AER and GHG. Internal variability greatly limits the detectability of AER- and GHG-forced trend patterns in individual realizations based on pattern correlation metrics, especially during the historical period, highlighting the need for LEs. We estimate that <20% of the spatial variances of observed precipitation and SST trends are attributable to AER and GHG forcing, although model biases in patterns of forced response and signal-to-noise may affect this estimate.

[1]  C. Deser,et al.  Pattern Recognition Methods to Separate Forced Responses from Internal Variability in Climate Model Ensembles and Observations , 2020, Journal of Climate.

[2]  B. Santer,et al.  Human influence on joint changes in temperature, rainfall and continental aridity , 2020, Nature Climate Change.

[3]  Christopher J. Smith,et al.  Sensitivity of Historical Climate Simulations to Uncertain Aerosol Forcing , 2020, Geophysical Research Letters.

[4]  J. Randerson,et al.  Insights from Earth system model initial-condition large ensembles and future prospects , 2020, Nature Climate Change.

[5]  G. Hegerl,et al.  Forced and Unforced Decadal Behavior of the Interhemispheric SST Contrast during the Instrumental Period (1881–2012): Contextualizing the Late 1960s–Early 1970s Shift , 2020, Journal of Climate.

[6]  J. Mülmenstädt,et al.  Bounding Global Aerosol Radiative Forcing of Climate Change , 2020, Reviews of geophysics.

[7]  Lukas Gudmundsson,et al.  Emulating Earth system model temperatures with MESMER: from global mean temperature trajectories to grid-point-level realizations on land , 2018, Earth System Dynamics.

[8]  C. Deser,et al.  Partitioning climate projection uncertainty with multiple large ensembles and CMIP5/6 , 2020, Earth System Dynamics.

[9]  E. Hawkins,et al.  Accelerated increases in global and Asian summer monsoon precipitation from future aerosol reductions , 2020, Atmospheric Chemistry and Physics.

[10]  Sarah M. Kang,et al.  Strong remote control of future equatorial warming by off-equatorial forcing , 2020, Nature Climate Change.

[11]  J. Mülmenstädt,et al.  Surprising similarities in model and observational aerosol radiative forcing estimates , 2019, Atmospheric chemistry and physics.

[12]  D. Stevenson,et al.  Climate Forcing and Response to Greenhouse Gases, Aerosols, and Ozone in CESM1 , 2019, Journal of Geophysical Research: Atmospheres.

[13]  A. Dai,et al.  Nonlinear Climate Responses to Increasing CO2 and Anthropogenic Aerosols Simulated by CESM1 , 2019, Journal of Climate.

[14]  Masahiro Watanabe,et al.  Extratropical–Tropical Interaction Model Intercomparison Project (Etin-Mip): Protocol and Initial Results , 2019 .

[15]  N. Maher,et al.  How large does a large ensemble need to be? , 2019, Earth System Dynamics.

[16]  J. Hurrell,et al.  Viewing Forced Climate Patterns Through an AI Lens , 2019, Geophysical Research Letters.

[17]  T. Mauritsen,et al.  Emergent constraints on Earth’s transient and equilibrium response to doubled CO2 from post-1970s global warming , 2019, Nature Geoscience.

[18]  B. Santer,et al.  Quantifying stochastic uncertainty in detection time of human-caused climate signals , 2019, Proceedings of the National Academy of Sciences.

[19]  N. Meinshausen,et al.  Uncovering the Forced Climate Response from a Single Ensemble Member Using Statistical Learning , 2019, Journal of Climate.

[20]  B. Samset,et al.  Emerging Asian aerosol patterns , 2019, Nature Geoscience.

[21]  D. Battisti,et al.  Attributing Historical and Future Evolution of Radiative Feedbacks to Regional Warming Patterns using a Green’s Function Approach: The Preeminence of the Western Pacific , 2019, Journal of Climate.

[22]  Climate Effects of Anthropogenic Aerosol Forcing on Tropical Precipitation and Circulations , 2019, Journal of Climate.

[23]  N. Gillett,et al.  The Canadian Earth System Model version 5 (CanESM5.0.3) , 2019, Geoscientific Model Development.

[24]  B. Stevens,et al.  The Max Planck Institute Grand Ensemble: Enabling the Exploration of Climate System Variability , 2019, Journal of Advances in Modeling Earth Systems.

[25]  A. Giannini,et al.  The role of aerosols and greenhouse gases in Sahel drought and recovery , 2018, Climatic Change.

[26]  G. Hegerl,et al.  Impacts of the 1900–74 Increase in Anthropogenic Aerosol Emissions from North America and Europe on Eurasian Summer Climate , 2018, Journal of Climate.

[27]  K. Caldeira,et al.  Divergent global-scale temperature effects from identical aerosols emitted in different regions , 2018, Nature Communications.

[28]  D. Frierson,et al.  Tropical Precipitation and Cross‐Equatorial Heat Transport in Response to Localized Heating: Basin and Hemisphere Dependence , 2018, Geophysical Research Letters.

[29]  C. Deser,et al.  Internal Variability and Regional Climate Trends in an Observational Large Ensemble , 2018, Journal of Climate.

[30]  G. Hegerl,et al.  Detectable Impact of Local and Remote Anthropogenic Aerosols on the 20th Century Changes of West African and South Asian Monsoon Precipitation , 2018 .

[31]  C. Deser,et al.  Fast Response of the Tropics to an Abrupt Loss of Arctic Sea Ice via Ocean Dynamics , 2018 .

[32]  U. Schneider,et al.  The Global Precipitation Climatology Project (GPCP) Monthly Analysis (New Version 2.3) and a Review of 2017 Global Precipitation. , 2018, Atmosphere.

[33]  W. G. Strand,et al.  Predicting Near-Term Changes in the Earth System: A Large Ensemble of Initialized Decadal Prediction Simulations Using the Community Earth System Model , 2018, Bulletin of the American Meteorological Society.

[34]  Dong Eun Lee,et al.  Fast Adjustments of the Asian Summer Monsoon to Anthropogenic Aerosols , 2018, Geophysical research letters.

[35]  Sarah M. Kang,et al.  Extratropical forcing and tropical rainfall distribution: energetics framework and ocean Ekman advection , 2018, npj Climate and Atmospheric Science.

[36]  B. Stevens.  Reply to “Comments on ‘Rethinking the Lower Bound on Aerosol Radiative Forcing’” , 2015, Journal of Climate.

[37]  J. Fasullo,et al.  Forced changes to twentieth century ENSO diversity in a last Millennium context , 2019, Climate Dynamics.

[38]  B. Soden.  The Large Scale Dynamical Response of Clouds to Aerosol Forcing , 2017 .

[39]  Thomas M. Smith,et al.  Extended Reconstructed Sea Surface Temperature, Version 5 (ERSSTv5): Upgrades, Validations, and Intercomparisons , 2017 .

[40]  Johannes W. Kaiser,et al.  Historic global biomass burning emissions for CMIP6 (BB4CMIP) based on merging satellite observations with proxies and fire models (1750-2015) , 2017 .

[41]  Karen A. McKinnon,et al.  An “Observational Large Ensemble” to Compare Observed and Modeled Temperature Trend Uncertainty due to Internal Variability , 2017 .

[42]  B. Soden,et al.  Hemispheric climate shifts driven by anthropogenic aerosol–cloud interactions , 2017 .

[43]  T. Andrews,et al.  PDRMIP: A Precipitation Driver and Response Model Intercomparison Project, Protocol and preliminary results. , 2017, Bulletin of the American Meteorological Society.

[44]  C. Deser,et al.  The Role of Ocean Heat Transport in the Global Climate Response to Projected Arctic Sea Ice Loss , 2016 .

[45]  A. Gettelman,et al.  Climate Feedback Variance and the Interaction of Aerosol Forcing and Feedbacks , 2016 .

[46]  S. Xie,et al.  Comparison of Climate Response to Anthropogenic Aerosol versus Greenhouse Gas Forcing: Distinct Patterns , 2016 .

[47]  C. Deser,et al.  Forced and Internal Components of Winter Air Temperature Trends over North America during the past 50 Years: Mechanisms and Implications* , 2016 .

[48]  S. Ghan,et al.  Challenges in constraining anthropogenic aerosol effects on cloud radiative forcing using present-day spatiotemporal variability , 2016, Proceedings of the National Academy of Sciences.

[49]  J. Lamarque,et al.  The importance of aerosol scenarios in projections of future heat extremes , 2018, Climatic Change.

[50]  B. Sanderson,et al.  Does extreme precipitation intensity depend on the emissions scenario? , 2015 .

[51]  K.,et al.  The Community Earth System Model (CESM) large ensemble project: a community resource for studying climate change in the presence of internal climate variability , 2015 .

[52]  C. Deser,et al.  Quantifying the Role of Internal Climate Variability in Future Climate Trends , 2015 .

[53]  Karen L. Smith,et al.  The impact of ozone depleting substances on the circulation, temperature, and salinity of the Southern Ocean: An attribution study with CESM1(WACCM) , 2015 .

[54]  E. Fischer,et al.  Anthropogenic contribution to global occurrence of heavy-precipitation and high-temperature extremes , 2015 .

[55]  Kenneth S. Carslaw,et al.  Quantifying sources of inter‐model diversity in the cloud albedo effect , 2015 .

[56]  B. Dong,et al.  The Impacts of European and Asian Anthropogenic Sulfur Dioxide Emissions on Sahel Rainfall , 2014 .

[57]  K. Taylor,et al.  Quantifying components of aerosol‐cloud‐radiation interactions in climate models , 2014 .

[58]  Sarah M. Kang,et al.  Sensitivity of Intertropical Convergence Zone Movement to the Latitudinal Position of Thermal Forcing , 2014 .

[59]  Claudia Tebaldi,et al.  Pattern scaling: Its strengths and limitations, and an update on the latest model simulations , 2014, Climatic Change.

[60]  D. Shindell,et al.  Anthropogenic and Natural Radiative Forcing , 2014 .

[61]  S. Xie,et al.  Similar spatial patterns of climate responses to aerosol and greenhouse gas changes , 2013 .

[62]  D. Frierson,et al.  Interhemispheric Temperature Asymmetry over the Twentieth Century and in Future Projections , 2013 .

[63]  Andrew S. Jones,et al.  Asymmetric forcing from stratospheric aerosols impacts Sahelian rainfall , 2013 .

[64]  Sarah M. Kang,et al.  Anthropogenic sulfate aerosol and the southward shift of tropical precipitation in the late 20th century , 2013 .

[65]  J. Curry,et al.  Berkeley Earth Temperature Averaging Process , 2013 .

[66]  P. Rasch,et al.  Climate response of the South Asian monsoon system to anthropogenic aerosols , 2012 .

[67]  Richard Neale,et al.  Toward a Minimal Representation of Aerosols in Climate Models: Description and Evaluation in the Community Atmosphere Model CAM5 , 2012 .

[68]  Karl E. Taylor,et al.  An overview of CMIP5 and the experiment design , 2012 .

[69]  C. Deser,et al.  Uncertainty in climate change projections: the role of internal variability , 2012, Climate Dynamics.

[70]  S. Klein,et al.  Global simulations of ice nucleation and ice supersaturation with an improved cloud scheme in the Community Atmosphere Model , 2010 .

[71]  David S. Lee,et al.  Historical (1850–2000) gridded anthropogenic and biomass burning emissions of reactive gases and aerosols: methodology and application , 2010 .

[72]  C. Deser,et al.  Global warming pattern formation: sea surface temperature and rainfall. , 2010 .

[73]  G. Vecchi,et al.  Climate Response of the Equatorial Pacific to Global Warming , 2009 .

[74]  E. Hawkins,et al.  The Potential to Narrow Uncertainty in Regional Climate Predictions , 2009 .

[75]  Yi Ming,et al.  Nonlinear Climate and Hydrological Responses to Aerosol Effects , 2009 .

[76]  R. Seager,et al.  Forced and Internal Twentieth-Century SST Trends in the North Atlantic* , 2009 .

[77]  Andrew Gettelman,et al.  A new two-moment bulk stratiform cloud microphysics scheme in the Community Atmosphere Model, version 3 (CAM3). Part I: Description and numerical tests , 2008 .

[78]  B. Soden,et al.  Robust Responses of the Hydrological Cycle to Global Warming , 2006 .

[79]  W. Collins,et al.  Description of the NCAR Community Atmosphere Model (CAM 3.0) , 2004 .

[80]  J. Neelin,et al.  Tropical drought regions in global warming and El Niño teleconnections , 2003 .

[81]  Elizabeth C. Kent,et al.  Global analyses of sea surface temperature, sea ice, and night marine air temperature since the late nineteenth century , 2003 .

[82]  Leon D. Rotstayn,et al.  Tropical Rainfall Trends and the Indirect Aerosol Effect , 2002 .

[83]  B. Santer,et al.  Detecting greenhouse-gas-induced climate change with an optimal fingerprint method , 1996 .

[84]  Syukuro Manabe,et al.  Century-scale effects of increased atmospheric C02 on the ocean–atmosphere system , 1993, Nature.