The Norwegian Earth System Model, NorESM1-M – Part 2: Climate response and scenario projections

Abstract. NorESM is a generic name of the Norwegian earth system model. The first version is named NorESM1, and has been applied with medium spatial resolution to provide results for CMIP5 ( http://cmip-pcmdi.llnl.gov/cmip5/index.html ) without (NorESM1-M) and with (NorESM1-ME) interactive carbon-cycling. Together with the accompanying paper by Bentsen et al. (2012), this paper documents that the core version NorESM1-M is a valuable global climate model for research and for providing complementary results to the evaluation of possible anthropogenic climate change. NorESM1-M is based on the model CCSM4 operated at NCAR, but the ocean model is replaced by a modified version of MICOM and the atmospheric model is extended with online calculations of aerosols, their direct effect and their indirect effect on warm clouds. Model validation is presented in the companion paper (Bentsen et al., 2012). NorESM1-M is estimated to have equilibrium climate sensitivity of ca. 2.9 K and a transient climate response of ca. 1.4 K. This sensitivity is in the lower range amongst the models contributing to CMIP5. Cloud feedbacks dampen the response, and a strong AMOC reduces the heat fraction available for increasing near-surface temperatures, for evaporation and for melting ice. The future projections based on RCP scenarios yield a global surface air temperature increase of almost one standard deviation lower than a 15-model average. Summer sea-ice is projected to decrease considerably by 2100 and disappear completely for RCP8.5. The AMOC is projected to decrease by 12%, 15–17%, and 32% for the RCP2.6, 4.5, 6.0, and 8.5, respectively. Precipitation is projected to increase in the tropics, decrease in the subtropics and in southern parts of the northern extra-tropics during summer, and otherwise increase in most of the extra-tropics. Changes in the atmospheric water cycle indicate that precipitation events over continents will become more intense and dry spells more frequent. Extra-tropical storminess in the Northern Hemisphere is projected to shift northwards. There are indications of more frequent occurrence of spring and summer blocking in the Euro-Atlantic sector, while the amplitude of ENSO events weakens although they tend to appear more frequently. These indications are uncertain because of biases in the model's representation of present-day conditions. Positive phase PNA and negative phase NAO both appear less frequently under the RCP8.5 scenario, but also this result is considered uncertain. Single-forcing experiments indicate that aerosols and greenhouse gases produce similar geographical patterns of response for near-surface temperature and precipitation. These patterns tend to have opposite signs, although with important exceptions for precipitation at low latitudes. The asymmetric aerosol effects between the two hemispheres lead to a southward displacement of ITCZ. Both forcing agents, thus, tend to reduce Northern Hemispheric subtropical precipitation.

[1]  M. Noguer,et al.  Climate change 2001: The scientific basis. Contribution of Working Group I to the Third Assessment Report of the Intergovernmental Panel on Climate Change , 2002 .

[2]  K. Swanson,et al.  Storm Track Dynamics , 2002, The Global Circulation of the Atmosphere.

[3]  R. Reynolds,et al.  The NCEP/NCAR 40-Year Reanalysis Project , 1996, Renewable Energy.

[4]  J. Barkmeijer,et al.  Optimal atmospheric forcing perturbations for the cold-ocean warm-land pattern , 2008 .

[5]  A. Bratseth.  Eddy Acceleration of the Mean Flow in the Atmosphere , 2001 .

[6]  N. Diffenbaugh,et al.  Higher Hydroclimatic Intensity with Global Warming , 2011 .

[7]  Stefan Rahmstorf,et al.  On the stability of the Atlantic meridional overturning circulation , 2009, Proceedings of the National Academy of Sciences.

[8]  John F. B. Mitchell,et al.  The time‐dependence of climate sensitivity , 2000 .

[9]  Nils Wedi,et al.  High-Resolution Global Climate Simulations with the ECMWF Model in Project Athena: Experimental Design, Model Climate, and Seasonal Forecast Skill , 2012 .

[10]  Christoph Heinze,et al.  Evaluation of the carbon cycle components in the Norwegian Earth System Model (NorESM) , 2012 .

[11]  A. Sterl,et al.  The ERA‐40 re‐analysis , 2005 .

[12]  Tim N. Palmer,et al.  Signature of recent climate change in frequencies of natural atmospheric circulation regimes , 1999, Nature.

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

[14]  G. Danabasoglu,et al.  The Community Climate System Model Version 4 , 2011 .

[15]  J. Murphy.  Transient Response of the Hadley Centre Coupled Ocean-Atmosphere Model to Increasing Carbon Dioxide. Part III: Analysis of Global-Mean Response Using Simple Models , 1995 .

[16]  A. Barnston,et al.  Classification, seasonality and persistence of low-frequency atmospheric circulation patterns , 1987 .

[17]  Philip J. Rasch,et al.  Characteristics of Atmospheric Transport Using Three Numerical Formulations for Atmospheric Dynamics in a Single GCM Framework , 2006 .

[18]  Corinna Hoose,et al.  The Norwegian Earth System Model, NorESM1-M - Part 1: Description and basic evaluation , 2012 .

[19]  M. Latif,et al.  Evaluation of Different Methods to Assess Model Projections of the Future Evolution of the Atlantic Meridional Overturning Circulation , 2007 .

[20]  Richard Neale,et al.  The Madden–Julian Oscillation in CCSM4 , 2011 .

[21]  Andrew Gettelman,et al.  Constraining cloud droplet number concentration in GCMs suppresses the aerosol indirect effect , 2009 .

[22]  G. Branstator,et al.  “Modes of Variability” and Climate Change , 2009 .

[23]  Bin Wang,et al.  Interdecadal changes in El Niño onset in the last four decades , 1995 .

[24]  Brian J. Hoskins,et al.  A new perspective on blocking , 2003 .

[25]  Christoph Heinze,et al.  An isopycnic ocean carbon cycle model , 2009 .

[26]  Trude Storelvmo,et al.  Aerosol-climate interactions in the CAM-Oslo atmospheric GCM and investigation of associated basic shortcomings , 2008 .

[27]  A. Bratseth.  Zonal‐mean transport characteristics of ECMWF re‐analysis data , 2003 .

[28]  A. Kirkevåg,et al.  Global direct radiative forcing by process‐parameterized aerosol optical properties , 2002 .

[29]  Seon Tae Kim,et al.  The two types of ENSO in CMIP5 models , 2012 .

[30]  A. Kirkevåg,et al.  Climate‐induced changes in sea salt aerosol number emissions: 1870 to 2100 , 2013 .

[31]  Jón Egill Kristjánsson,et al.  Studies of the aerosol indirect effect from sulfate and black carbon aerosols , 2002 .

[32]  Philip J. Rasch,et al.  Effects of Convective Momentum Transport on the Atmospheric Circulation in the Community Atmosphere Model, Version 3 , 2008 .

[33]  T. Iversen,et al.  Correction to “A scheme for process-tagged SO4 and BC aerosols in NCAR-CCM3: Validation and sensitivity to cloud processes” , 2003 .

[34]  T. Iversen,et al.  A scheme for process‐tagged SO4 and BC aerosols in NCAR CCM3: Validation and sensitivity to cloud processes , 2002 .

[35]  David B. Stephenson,et al.  On the existence of multiple climate regimes , 2004 .

[36]  A. Stohl,et al.  A close look at oceanic sources of continental precipitation , 2011 .

[37]  M. Chin,et al.  Radiative forcing of the direct aerosol effect from AeroCom Phase II simulations , 2012 .

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

[39]  R. Mizuta,et al.  Future change in wintertime atmospheric blocking simulated using a 20‐km‐mesh atmospheric global circulation model , 2009 .

[40]  Louis J. Bajuk,et al.  Interpretation of Interdecadal Trends in Northern Hemisphere Surface Air Temperature , 1996 .

[41]  H. Drange,et al.  Description and evaluation of the bergen climate model: ARPEGE coupled with MICOM , 2003 .

[42]  K. Taylor,et al.  Forcing, feedbacks and climate sensitivity in CMIP5 coupled atmosphere‐ocean climate models , 2012 .

[43]  H. Drange,et al.  Towards a more saline North Atlantic and a fresher Arctic under global warming , 2006 .

[44]  Philip J. Rasch,et al.  A Comparison of the CCM3 Model Climate Using Diagnosed and Predicted Condensate Parameterizations , 1998 .

[45]  Jens Debernard,et al.  On the additivity of climate response to anthropogenic aerosols and CO2, and the enhancement of future global warming by carbonaceous aerosols , 2008 .

[46]  N. McFarlane,et al.  Sensitivity of Climate Simulations to the Parameterization of Cumulus Convection in the Canadian Climate Centre General Circulation Model , 1995, Data, Models and Analysis.

[47]  Andrew Gettelman,et al.  The Influence of Local Feedbacks and Northward Heat Transport on the Equilibrium Arctic Climate Response to Increased Greenhouse Gas Forcing , 2012 .

[48]  Steven J. Ghan,et al.  Predicting cloud droplet number concentration in community atmosphere model (CAM)-Oslo , 2006 .

[49]  W. Munk,et al.  Abyssal recipes II: energetics of tidal and wind mixing , 1998 .

[50]  Franco Molteni,et al.  On the operational predictability of blocking , 1990 .

[51]  Bin Wang,et al.  Interdecadal Change of the Structure of the ENSO Mode and Its Impact on the ENSO Frequency , 2000 .

[52]  L. Ferranti,et al.  Northern Hemisphere atmospheric blocking as simulated by 15 atmospheric general circulation models in the period 1979–1988 , 1998 .

[53]  R. Neale,et al.  The Mean Climate of the Community Atmosphere Model (CAM4) in Forced SST and Fully Coupled Experiments , 2013 .

[54]  Andrew Gettelman,et al.  The Evolution of Climate Sensitivity and Climate Feedbacks in the Community Atmosphere Model , 2012 .

[55]  W. Landman.  Climate change 2007: the physical science basis , 2010 .

[56]  J. Wallace,et al.  Annular Modes in the Extratropical Circulation. Part I: Month-to-Month Variability* , 2000 .

[57]  M. Blackmon,et al.  A Climatological Spectral Study of the 500 mb Geopotential Height of the Northern Hemisphere. , 1976 .

[58]  T. Diehl,et al.  Black carbon vertical profiles strongly affect its radiative forcing uncertainty , 2012 .

[59]  K. Trenberth,et al.  Observations: Surface and Atmospheric Climate Change , 2007 .

[60]  Michael Schulz,et al.  Aerosol–climate interactions in the Norwegian Earth System Model – NorESM1-M , 2012 .

[61]  R. Neale,et al.  The Impact of Convection on ENSO: From a Delayed Oscillator to a Series of Events , 2008 .

[62]  Charles S. Zender,et al.  Linking snowpack microphysics and albedo evolution , 2006 .

[63]  E. O. Hulburt,et al.  SORCE CONTRIBUTIONS TO NEW UNDERSTANDING OF GLOBAL CHANGE AND SOLAR VARIABILITY , 2005 .

[64]  Trude Storelvmo,et al.  Aerosol-cloud-climate interactions in the climate model CAM-Oslo , 2008 .

[65]  Supplementary Information External forcing as a metronome for Atlantic multidecadal variability Odd , 2010 .

[66]  Analysis of the mid-latitude weather regimes in the 200-year control integration of the SINTEX model , 2003 .

[67]  Andrew Gettelman,et al.  Evaluation of cloud and water vapor simulations in CMIP5 climate models using NASA “A-Train” satellite observations , 2012 .

[68]  J. Barkmeijer,et al.  Optimal atmospheric forcing perturbations for the cold-ocean warm-land pattern , 2008 .

[69]  G. Danabasoglu,et al.  Climate Sensitivity of the Community Climate System Model, Version 4 , 2012 .

[70]  Elizabeth A. Barnes,et al.  A methodology for the comparison of blocking climatologies across indices, models and climate scenarios , 2012, Climate Dynamics.

[71]  James J. Hack,et al.  The Dynamical Simulation of the Community Atmosphere Model Version 3 (CAM3) , 2006 .

[72]  Chris Harris,et al.  Improved Atlantic winter blocking in a climate model , 2011 .

[73]  Nils Gunnar Kvamstø,et al.  Simulated pre-industrial climate in Bergen Climate Model (version 2): model description and large-scale circulation features , 2009 .

[74]  Charles S. Zender,et al.  A monthly and latitudinally varying volcanic forcing dataset in simulations of 20th century climate , 2003 .

[75]  Cecilie Mauritzen,et al.  Dilution of the Northern North Atlantic Ocean in Recent Decades , 2005, Science.

[76]  J. Lean,et al.  Modeling the Sun’s Magnetic Field and Irradiance since 1713 , 2005 .

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

[78]  K. Trenberth,et al.  The changing character of precipitation , 2003 .

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

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

[81]  Harald Lejenäs,et al.  Characteristics of northern hemisphere blocking as determined from a long time series of observational data , 1983 .

[82]  A. Thomson,et al.  The representative concentration pathways: an overview , 2011 .

[83]  I. Medhaug,et al.  North Atlantic 20th century multidecadal variability in coupled climate models: sea surface temperature and ocean overturning circulation , 2011 .

[84]  G. North,et al.  Empirical Orthogonal Functions: The Medium is the Message , 2009 .

[85]  G. Boer,et al.  Climate sensitivity and response , 2003 .

[86]  E. Guilyardi,et al.  A first look at ENSO in CMIP5 , 2012 .

[87]  K. Trenberth.  Changes in precipitation with climate change , 2011 .

[88]  Franco Molteni,et al.  Predictability of Weather and Climate: On the predictability of flow-regime properties on interannual to interdecadal timescales , 2006 .

[89]  Jeffrey H. Yin,et al.  A consistent poleward shift of the storm tracks in simulations of 21st century climate , 2005 .

[90]  J. Wallace,et al.  Teleconnections in the Geopotential Height Field during the Northern Hemisphere Winter , 1981 .

[91]  Michael Ghil,et al.  ADVANCED SPECTRAL METHODS FOR CLIMATIC TIME SERIES , 2002 .

[92]  A. Stohl,et al.  Remote sources of water vapor forming precipitation on the Norwegian west coast at 60°N–a tale of hurricanes and an atmospheric river , 2008 .

[93]  W. G. Strand,et al.  Climate System Response to External Forcings and Climate Change Projections in CCSM4 , 2012 .

[94]  Kevin E. Trenberth,et al.  Atmospheric Moisture Transports from Ocean to Land and Global Energy Flows in Reanalyses , 2011 .

[95]  Tim Palmer,et al.  A Nonlinear Dynamical Perspective on Climate Prediction , 1999 .

[96]  Kevin E. Trenberth,et al.  The Definition of El Niño. , 1997 .

[97]  Ian T. Jolliffe,et al.  Empirical orthogonal functions and related techniques in atmospheric science: A review , 2007 .

[98]  Jonathan M. Gregory,et al.  A new method for diagnosing radiative forcing and climate sensitivity , 2004 .

[99]  J. Janowiak,et al.  The Version 2 Global Precipitation Climatology Project (GPCP) Monthly Precipitation Analysis (1979-Present) , 2003 .

[100]  Annica M. L. Ekman,et al.  The effect of sea ice loss on sea salt aerosol concentrations and the radiative balance in the Arctic , 2010 .

[101]  Kevin E. Trenberth,et al.  On the evolution of the southern oscillation , 1987 .

[102]  J. Shukla,et al.  Does ENSO Force the PNA , 2002 .

[103]  Jens Debernard,et al.  Response of the climate system to aerosol direct and indirect forcing: Role of cloud feedbacks , 2005 .

[104]  Kevin E. Trenberth,et al.  Progress during TOGA in understanding and modeling global teleconnections associated with tropical sea surface temperatures , 1998 .