Celine J. W Bonfils


Portrait of  Celine J. W Bonfils
  • Title
    Staff Scientist
  • Email
  • Phone
    (925) 423-9923
  • Organization

Research Interests

I am a climate scientist interested in the changes in climate, past, historical, and future. The heart of my research is to identify “fingerprints” of natural and human influences on global climate (e.g., rainfall, droughts, extremes, etc…), tease apart the geographical and temporal climate responses to greenhouse gas emissions, particulate pollution and volcanic eruptions in climate simulations and observations, and constrain climate sensitivity and aerosol forcing in climate models. My research interests also include the evaluation of climate model performance, the role of human activities (including irrigation) on the climate of the western US, the influence of low-frequency climate modes of variability on hydrological variability, and the interpretation of climate reconstructions of the recent past.

Key words:

  • Detection and attribution | precursors of droughts | climate variability and change | noise and signal separation | pattern-based fingerprinting | deep learning | model quality information | uncertainties quantification
  • ITCZ | ENSO variability | role of irrigation and vegetation
  • Global scale | California | Sahel |Western U.S. climate


  • Lawrence Livermore National Laboratory | Research scientist | Deputy Group Leader 2014-2022 | Group Leader of the Climate Sensitivity and Impacts Group since 2022.
  • U.C. Merced and Lawrence Livermore National Laboratory | Postdoctoral Fellow | 2005-2009
  • U.C. Berkeley | Postdoctoral Fellow, Berkeley Atmospheric Sciences Center | 2001-2004
  • Atomic Energy Commission | Ph.D. and Research Associate | 1996-2001

Ph.D. Oceanography, Meteorology, and Environment, University Paris VI, France, 2001

M.Sc., Meteorology, Environment, University of Paris VI, France, 1996

B.S. Chemistry, University of Cergy-Pontoise, France, 1995

For the full list, see | orcid | ResearcherID | Google Scholar |: Scopus

Lee, J., Gleckler, P. J., Ahn, M.-S., Ordonez, A., Ullrich, P.A., Sperber, K., Taylor, K., Planton, Y., Guilyardi, E., Durack, P., Bonfils, C., et al.: Objective Evaluation of Earth System Models: PCMDI Metrics Package (PMP) version 3, EGUsphere [preprint], doi:10.5194/egusphere-2023-2720, 2023.

Persad G., B. Samset, L. Wilcox, R. Allen, M. Bollasina, B. Booth, C. Bonfils, [...], 2023: Rapidly evolving aerosol emissions are a dangerous omission from near-term climate risk assessments, Env. Res. : Clim., doi: 10.1088/2752-5295/acd6af, accepted. BER Research Highlight 

Persad, G., B. Samset and L. Wilcox, 2022: Aerosols must be included in climate risk assessments, co- sign.: R. Allen, [...], B. Booth, C. Bonfils [...], Nature, 611, doi: 10.1038/d41586-022-03763-9 BER Research Highlight 

Po-Chedley, S, JT Fasullo, N Siler, EA Barnes, ZM Labe, C Bonfils, BD Santer, 2022: Internal variability and forcing influence model–satellite differences in the rate of tropical tropospheric warming, PNAS, 119, doi: 10.1073/pnas.2209431119 BER Research Highlight

Peace, AH, BBB Booth, LA Regayre, KS Carslaw, DMH Sexton, C Bonfils, and JW Rostron, 2022: Evaluating uncertainty in aerosol forcing of tropical precipitation shifts, Earth Syst. Dyn., 13, doi: 10.5194/esd-13-1215-2022 BER Research Highlight  

Wang, Y, J Mao, F Hoffman, C Bonfils, H Douville, M Jin, P Thornton, [..], 2022: Quantification of human contribution to soil moisture–based droughts, Nature Com. 13, doi: 10.1038/s41467-022-34071-5 BER Research Highlight 

Pan, B, GJ Anderson, A Goncalves, DD Lucas, C Bonfils, J Lee, 2022, Improving seasonal forecast using probabilistic deep learning, 2022, J. Advances in Modeling Earth Systems, doi:10.1029/2021MS002766

Santer, BD, S Po-Chedley, [..], C Bonfils, G Pallotta, M Zelinka, [...], 2022: Robust anthropogenic signal identified in the seasonal cycle of TMT, J. Climate, doi:10.1175/JCLI-D-21-0766 Early Online Release

Marvel, K, B Cook, C Bonfils, J E Smerdon, A P Williams, H Liu 2021: Projected Changes to Hydroclimate Seasonality in the Continental United States, Earth's Future, 9, doi:10.1029/2021ef002019 BER Research Highlight

Pan, B, GJ Anderson, A Goncalves, DD Lucas, C Bonfils, J Lee, Y Tian, H-Y Ma 2021: Learning to Correct Climate Projection Biases, J. Advances in Modeling Earth Systems, 13, e2021MS002509. doi:10.1029/2021MS002509 BER Research Highlight

Lee, J, K Sperber, P Gleckler, K Taylor, and C Bonfils, 2021: Benchmarking performance changes in the simulation of extratropical modes of variability across CMIP generations. J. Climate, 34, 6945–6969, doi:10.1175/JCLI-D-20-0832.1 BER Research Highlight

Douville, H, K Raghavan, J Renwick, et al., and contributing authors, 2021: Water Cycle Changes. In Climate Change 2021: The Physical Science Basis. Working Group I to the 6th Assessment Report of the IPCC [Masson-Delmotte et al (eds.)]., doi:10.1017/9781009157896.010

Bonfils, C, B D Santer, J Fyfe, K Marvel, T Phillips, S Zimmerman, 2020: Human influence on joint changes in temperature, rainfall, and continental aridity Nature Climate. Change, 10, doi:10.1038/s41558-020-0821-1 BER Research Highlight  | LLNL PLS Directorate Award | Journal cover article, LLNL PLS Directorate Award, 1 plenary talk (AMOS-2020)

Pendergrass, AG, M Hobbins, A Hoell, A AghaKouchak, C Bonfils, et al. 2020:  Flash droughts present a new challenge for subseasonal-to-seasonal prediction. Nature Climate Change 10, 191–199. doi:10.1038/s41558-020-0709-0 BER Research Highlight

Santer, BD, C Bonfils, Q Fu, JC Fyfe, GC Hegerl, C Mears, JF Painter, S Po-Chedley, FJ Wentz, MD Zelinka, and C-Z Zou, 2018: Celebrating the anniversary of three key events in climate. Nature Climate Change, doi: 10.1038/s41558-019-0424-x BER Research Highlight

Santer, BD, JC Fyfe, S Solomon, JF Painter, C Bonfils, G Pallotta, and MD Zelinka, October 2019: Quantifying stochastic uncertainty in detection time of human-caused climate signals. PNAS, 116, 19821-19827 doi: 10.1073/pnas.1904586116 BER Research Highlight

Phillips, TJ, CJW Bonfils, and C Zhang, 2018: Model consensus projections of U.S. regional hydroclimates under greenhouse warming, ERL, 14 (1), 014005, doi:10.1088/1748-9326/aaf03d  BER Research Highlight

Marvel, K, BI Cook, C Bonfils, PJ Durack, JE Smerdon, A Park Williams, 2019: Twentieth century hydroclimate changes consistent with human influence, Nature, doi.org/10.1038/s41586-019-1149-8  BER Research Highlight

Anderson, GJ, DD Lucas, and C Bonfils, 2018: Uncertainty analysis of simulations of the turn‐of‐the‐century drought in the western United States. J. Geophysical Research: Atmospheres, 123, 13,219–13,237. doi:10.1029/2017JD027824 BER Research Highlight

Santer BD, S Po-Chedley, MD Zelinka, I Cvijanovic, C Bonfils, PJ Durack, Q Fu, J Kiehl, C Mears, et al., 2018: Human influence on the seasonal cycle of tropospheric temperature, Science, 361, 245, 10.1126/science.aas8806, doi: 10.1126/science.aas8806 BER Research Highlight

Cvijanovic I, BD Santer, C Bonfils, D Lucas, , J Chiang, S Zimmerman, 2017: Future loss of Arctic sea-ice cover could drive a substantial decrease in California's rainfall, Nature Communication, 8, 1947, 10.1038/s41467-017-01907-4 doi:10.1038/s41467-017-01907-4  BER Research Highlight

Santer BD, R Neely III, G Meehl, J-F Lamarque, S Solomon, D Ridley, C Bonfils, J Painter, M Zelinka, 2017: Correspondence: Climate impact of volcanic forcing uncertainty, Nature Communication, submitted

Santer BD, JC Fyfe, G Pallotta, GM Flato, GA Meehl, MH England, E Hawkins, ME Mann, JF Painters, C Bonfils, et al., 2017: Causes of differences in model and satellite tropospheric warming rates, Nature Geoscience, 10, 478-485, doi: 10.1038/NGEO2973 doi:10.1038/NGEO2973  

Bonfils C, G Anderson, BD Santer, TJ Phillips, KE Taylor, M Cuntz, MD Zelinka, K Marvel et al., 2017: Competing influences of anthropogenic warming, ENSO, and plant physiology on future terrestrial aridity. J. Climate, 30, 6883-6904, doi:10.1175/JCLI-D-17-0005.1, BER Research Highlight

Marvel K, M Biasutti, C Bonfils, KE Taylor, 2017: Observed and Projected Changes to the Precipitation Annual Cycle, J. Climate, 30, 4983-4995, doi: 10.1175/JCLI-D-16-0572.1 BER Research Highlight

Santer B, S Solomon, D Ridley, J Fyfe, F Beltran, C Bonfils, J Painter, M Zelinka, 2015: Correspondence: Volcanic effects on climate, Nature Clim Ch, 6, 3-4 doi:10.1038/nclimate2859 BER Research Highlight

Marvel K, MD Zelinka, SA Klein, C Bonfils, PM Caldwell, C Doutriaux, BD Santer, KE Taylor, 2015: External influences on modeled and observed cloud trends, J. Climate, 28, 4820-4840, doi: 10.1175/JCLI-D-14-00734.1  BER Research Highlight

Phillips TJ, C Bonfils, 2015: Köppen bioclimatic evaluation of CMIP historical climate simulations, Env. Res. Lett., 10, 064005, doi:10.1088/1748-9326/10/6/064005 BER Research Highlight

Santer BD, S Solomon, C Bonfils, M D Zelinka, J F Painter, F Beltran, JC Fyfe, G Johannesson, C Mears, D A Ridley et al., 2015: Observed multi-variable signals of late 20th and early 21st century volcanic activity, Geophys. Res. Lett., 42: 500-509, doi:10.1002/2014GL062366 BER Research Highlight

Bonfils C, BD Santer, T J Phillips, K Marvel, R Leung, C Doutriaux, A Copotondi, 2015: Relative contributions of mean-state shifts and ENSO-driven variability to precipitation changes in a warming climate, J Climate, 28, 9997-10013, doi:10.1175/JCLI-D-15-0341.1 BER Research Highlight

Santer BD, C Bonfils, JF Painter, M Zelinka, C Mears, S Solomon, GA Schmidt, JC Fyfe, JNS Cole, L Nazarenko, KE Taylor, FJ Wentz, 2014: Volcanic contribution to decadal changes in tropospheric temperature, Nature Geoscience, 7: 185-189, , doi:10.1038/ngeo2098 BER Research Highlight

Marvel K, C Bonfils, 2013: Identifying external influences on global precipitation, PNAS, 110: 19301-19306, doi: 10.1073/pnas.1314382110 BER Research Highlight

Santer BD, JF Painter, C Bonfils, CA Mears, S Solomon, TML Wigley, PJ Gleckler, GA Schmidt, C Doutriaux, NP Gillett, KE Taylor, PW Thorne, FJ Wentz, 2013: Human and natural influences on the changing thermal structure of the atmosphere, PNAS, 110, 17235-17240, doi:10.1073/pnas.1305332110

Bonfils C, TJ Phillips, DM Lawrence, P Cameron-Smith, WJ Riley, ZM Subin, 2012: On the influence of shrub height and expansion on northern high latitude climate. Environmental Research Letters, 7, 015503, doi: 10.1088/1748-9326/7/1/015503

Bonfils C, and BD Santer 2011: Investigating the possibility of a human component in various Pacific Decadal Oscillation indices. Clim. Dyn.. 37, 1457–1468. doi: 10.1007/s00382-010-0920-1.

Hidalgo H, T Das, MD Dettinger, DR Cayan, DW Pierce, TP Barnett, G Bala, A Mirin, AW Wood, C Bonfils, BD Santer, and T Nozawa, 2009: Detection and attribution of streamflow timing changes to climate change in the western United States, J. Climate, 22, 3838-3855. doi:10.1175/2009JCLI2470.1

Santer BD, KE Taylor, PJ Gleckler, C Bonfils, TP Barnett, DW Pierce, TML Wigley, C Mears, F Wentz, W Brüggemann, N Gillett, al. 2009: Incorporating model quality information in climate change detection and attribution studies PNAS, 35, 14778-14783 doi/10.1073/pnas.0901736106

Pierce D, TP Barnett, HG Hidalgo T Das, C Bonfils, B Sander, G Bala, M Dettinger, D Cayan, A Mirin, AW Wood, and T Nozawa, 2008: Attribution of declining western US snowpack to human effects.  J. Climate, 21, 6425-6444, doi:10.1175/2008JCLI2405.1

Bonfils C, BD Santer, DW Pierce, H Hidalgo, G Bala, T Das, TP Barnett, M Dettinger, DR Cayan, C Doutriaux, AW Wood, A Mirin, T Nozawa, 2008: Detection and Attribution of temperature changes in the mountainous western United States. J. Climate, 21:6404-6424. doi: 10.1175/2008JCLI2397.1

Barnett T, D W Pierce, HG Hidalgo, C Bonfils, BD Santer, T Das, G Bala, AW Wood, T Nozawa, A Mirin, DR Cayan, and M Dettinger, 2008: Human-induced changes in the hydrology of the western United States, Science, 319: 1080-1083. doi: 10.1126/science.1152538

Bonfils C, P Duffy, B Santer, T Wigley, DB Lobell, TJ Phillips, and C Doutriaux, 2008: Identification of external influences on temperatures in California. Climate Change, 87:43-55. doi: 10.1007/s10584-007-9374-9

Lobell D, and C Bonfils, 2008: The effect of irrigation on regional temperatures: a spatial and temporal analysis of trends in California, 1934-2002. J. Climate, doi:21:2063-2071, 10.1175/2007JCLI1755.1

Bonfils C, P Duffy, and D Lobell, 2007: Comment on “Methodology and results of calculating Central California surface temperature trends: evidence of human-induced climate change?” by Christy et al. (2006). J. Climate, 20:4486-4489, doi: 10.1175/JCLI4247.1

Bonfils C, and D Lobell, 2007: Empirical evidence for a recent slowdown in irrigation-induced cooling. PNAS, 104: 13582-13587. doi: 10.1073/pnas.0700144104

Duffy P, C Bonfils, P Gleick, and D Lobell, 2007: Interpretating recent temperature trends in California. EOS Transactions, American Geophysical Union, 88:409-410

Lobell D, G Bala, C Bonfils, and P Duffy, 2006: Potential bias of model projected greenhouse warming in irrigated regions. Geophys. Res. Lett., 33, L13709, doi: 10.1029/2006GL026770

  • LLNL Director Science and Technology Award for Excellence in Publication for Po-Chedley et al (2023)
  • Eos Research Spotlight for Pan et al. (2022)
  • LLNL Physical and Life Science Directorate Award for Excellence in Publication for Bonfils et al. (2020)
  • LLNL Physical and Life Science Directorate Award for Excellent Publication for providing an important assessment of the role of Arctic sea-ice on CA precipitation (2018)
  • LLNL Physical and Life Science Directorate Award for Excellent Publication for providing an important assessment of temperature data that can be used to help guide climate policy (2017)
  • Mid-Career Recognition (EMCR) Program Award (2016)
  • LLNL Deputy Director for S&T Award for Excellence in Publication for Santer et al. 2015 (2016)
  • 2 LLNL Atmospheric Earth and Energy Division Spot Awards (2016)
  • LLNL GS/PLS Directorates Best Poster Award for the External Review Committee (2015)
  • LLNL Physical and Life Science Directorate Award for Excellent Publication for Marvel and Bonfils (2013)
  • Early Career Research Project Award (2012-2017) featured here
  • LLNL Outstanding Postdoc Fellow Award, Physical and Life Science Directorate (2009)
  • LLNL Atmospheric Earth and Energy Division Spot Award for exemplary performance in response to an important organizational need (2009)
  • LLNL Science and Technology Award (2008)
  • Citizens Award, United Nations Association, U.S.A. (2009)
  • Contributing author to Nobel Peace Prize Winning IPCC report (2007)
  • Ph.D. Appointment Award by French Atomic Energy Commission (1997-2000)
  • Contributing author of Chapter 8 of the IPCC Working Group I, 6th Assessment Report.
  • Contributing author of Chapter 8 of the IPCC Working Group I, 4th Assessment Report.
  • Bonfils C, D Lewden, K Taylor, A summary documentation of the PMIP models, PCMDI Report.