Pablo Ortega Montilla

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I am a climate scientist with a broad range of interests, including paleoclimatology, ocean dynamics, decadal prediction and climate feedbacks. To date, the bulk of my research efforts has focused on studying the past to learn for the future, with particular interest in the fate of the ocean circulation and its climate impacts.

I obtained my PhD degree at the Universidad Complutense de Madrid as a member of the PalMA research team, analyzing last millennium ocean variability.

Since then, three postdoctoral stays have allowed me to acquire a unique profile both as a climate modeller and paleo-climatologist. During the first, at the LSCE,  I worked linking Greenland ice core variability to the large-scale atmospheric circulation. In the second, at LOCEAN, I investigated the mechanisms responsible for the decadal variability in the IPSL model and developed a novel nudging tecnique to improve the initialization of the Atlantic Overturning Meridional Circulation. My last postdoc, at NCAS-Climate, was focused on understanding the controls of multidecadal variability (and predictability) in the North Atlantic.

I currently co-lead, together with Markus Donat, the Climate Prediction group of the Earth Science Department




  1. Volpi, D., V. L. Meccia, V. Guemas, P. Ortega, R. Bilbao, F.J. Doblas-Reyes, A. Amaral, P. Echevarria, R. Mahmood, and S. Corti "A novel initialisation technique for decadal climate predictions", Front Clim., accepted, 2021.
  2. Koenigk, T., R. Fuentes-Franco, V.L. Meccia, O. Gutjahr, L.C. Jackson, A.L. New, P. Ortega, C. Roberts, M. Roberts, T. Arsouze, D.  Iovino, M.-P. Moine, and D.V. Sein "Deep mixed ocean volume in the Labrador Sea in HighResMIP models", Clim. Dyn., accepted, 2021.
  3. Levine, X., I. Cvijanovic, P. Ortega, M. Donat, and E. Tourigny "Atmospheric feedback explains disparate climate response to regional Arctic sea ice loss", npj Climate and Atmospheric Science, accepted, 2021.
  4. Moreno-Chamarro, E., L.-P. Caron, P. Ortega, S. Loosveldt-Tomas,  and M.J. Roberts "Can we trust CMIP5/6 future projections of European winter precipitation?", Environ. Res. Lett., accepted, 2021, doi: 10.1088/1748-9326/abf28a.
  5. Exarchou, E., P. Ortega, B. Rodríguez-Fonseca, T. Losada, I. Polo and C. Prodhomme "Impact of Equatorial Atlantic Variability on ENSO Predictive Skill", Nat. Comms., 12, 1612, 2021, doi:10.1038/s41467-021-21857-2.
  6. Ortega, P., J.I. Robson, M. Menary, R.T. Sutton, A. Blaker, A. Germe, J.J.-M. Hirschi, B. Sinha, L. Hermanson and S. Yeager "Labrador Sea sub-surface density as a precursor of multi-decadal variability in the North Atlantic: a multi-model study", Earth Syst. Dynam., 12, 419–438, 2021, doi:10.5194/esd-2020-83.
  7. Bilbao, R., S. Wild, P. Ortega, J. Acosta-Navarro, T. Arsouze, P.-A. Bretonnière, L.-P. Caron, M. Castrillo, R. Cruz-García, I. Cvijanovic, F.J. Doblas-Reyes, M. Donat, E. Dutra, P. Echevarría, A.-C. Ho, S. Loosveldt-Tomas, E. Moreno-Chamarro, N. Pérez-Zanon, A. Ramos, Y. Ruprich-Robert, V. Sicardi, E. Tourigny and J. Vegas-Regidor "Assessment of a full-field initialised decadal climate prediction system with the CMIP6 version of EC-Earth", Earth Syst. Dynam.,12, 173–196, 2021, doi:10.5194/esd-12-173-2021.
  8. Cruz-García, R., P. Ortega, V. Guemas, J. Acosta-Navarro, F. Massonnet and F. Doblas-Reyes "An anatomy of Arctic sea ice forecast biases in the seasonal prediction system with EC-Earth", Clim. Dyn. 56, 1799–1813, 2020, doi:10.1007/s00382-020-05560-4.
  9. Moreno-Chamarro, E., P. Ortega and F. Massonnet "Impact of the ice thickness distribution discretization on the sea ice concentration variability in the NEMO3.6-LIM3 global ocean–sea ice model", Geosci. Model Dev., 13, 4773–4787, 2020, doi:10.5194/gmd-13-4773-2020.
  10. Roberts, M.J., L.C. Jackson, C.D. Roberts, V. Meccia, D. Docquier, T. Koenigk, P. Ortega, E. Moreno-Chamarro, A. Bellucci, A. Coward, S. Drijfhout, E. Exarchou, O. Gutjahr, H. Hewitt, D. Iovino, K. Lohmann, D. Putrasahan, R. Schiemann, J. Seddon, L. Terray, X. Xu, Q. Zhang, P. Chang, S.G. Yeager, F.S. Castruccio, S Zhang and L. Wu "Sensitivity of the Atlantic Meridional Overturning Circulation to Model Resolution in CMIP6 HighResMIP Simulations and Implications for Future Changes", Journal of Advances in Modeling Earth Systems 12, e2019MS002014, 2020, doi:10.1029/2019MS002014.
  11. Hernández A., C. Martin-Puertas, P. Moffa-Sánchez, E. Moreno-Chamarro, P. Ortega, S. Blockley, K.M. Cobb, L. Comas-Bru, S. Giralt, H. Goosse, J. Luterbacher, B. Martrat, R. Muscheler, A. Parnell, S. Pla-Rabes, J. Sjolte, A.A. Scaife, D. Swingedouw, E. Wise and  G. Xu "Modes of climate variability: Synthesis and review of proxy-based reconstructions through the Holocene", Earth-Science Reviews 208103286, 2020, doi:10.1016/j.earscirev.2020.103286.
  12. Batté L., I. Välisuo, M. Chevallier, J.C. Acosta-Navarro, P. Ortega and D. Smith "Summer predictions of Arctic sea ice edge in multi-model seasonal re-forecasts", Climate Dynamics 54, 5013–5029, 2020, doi:10.1007/s00382-020-05273-8.
  13. Smith D., and coauthors "North Atlantic climate far more predictable than models imply", Nature 583, 7968002020, doi:10.1038/s41586-020-2525-0
  14. Hermanson L., R. Bilbao, N. Dunstone, M. Ménégoz, P. Ortega, H. Pohlmann, J. Robson, D. Smith, G. Strand, C. Timmreck, S. Yeager and G. Danabasoglu "Robust multi-year climate impacts of volcanic eruptions in decadal prediction system", Journal of Geophysical Research - Atmospheres 125, e2019JD031739, 2020, doi: 10.1029/2019JD031739
  15. Michel S., D. Swingedouw, M. Chavent, P. Ortega, J. Mignot and M. Khodri "Reconstructing climatic modes of variability from proxy records: sensitivity to the methodological approach", Geoscientific Model Development 13,  841–858, 2020, doi:10.5194/gmd-13-841-2020
  16. Acosta-Navarro J.C., P. Ortega, L. Batté, D. Smith, P.A. Bretonnière, V. Guemas, F. Massonnet, V. Sicardi, V. Torralba,  E. Tourigny and  F.J. Doblas-Reyes "Link between autumnal Arctic Sea ice and Northern Hemisphere winter forecast skill", Geophysical Research Letters 47, e2019GL086753, 2020, doi: 10.1029/2019GL086753.
  17. Moat B., B. Sinha, S.A. Josey, J. Robson, P. Ortega, F. Sevellec, N.P. Holliday, G.D. McCarthy, A.L. New and J.J.-M. Hirschi "Insights into Decadal North Atlantic Sea Surface Temperature and Ocean Heat Content Variability from an Eddy-Permitting Coupled Climate Model", Journal of Climate 32, 6137-6161, 2019, doi: 10.1175/JCLI-D-18-0709.1.
  18. Moffa‐Sánchez P., E. Moreno‐Chamarro, D.J. Reynolds, P. Ortega, L. Cunningham, D. Swingedouw, D.E. Amrhein, J. Halfar, L. Jonkers, J.H. Jungclaus and K. Perner "Variability in the Northern North Atlantic and Arctic Oceans Across the Last Two Millennia: A Review", Paleoceanography and Paleoclimatology, 34, 1399-1436, 2019, doi: 10.1029/2018PA003508
  19. Acosta-Navarro J.C., P. Ortega, J. García-Serrano, V. Guemas, E. Tourigny, R. Cruz-García, F. Massonnet and F.J. Doblas-Reyes "December 2016: Linking the lowest Arctic sea-ice extent on record with the lowest European precipitation event on record", BAMS 100, Explaining Extreme Events of 2017, S43-S48, 2019, doi: 10.1175/BAMS-D-18-0097.1.
  20. Thornalley D., D. Oppo, P. Ortega, J. Robson, C. Brierley, R. Davis, I. Hall, L. Keigwin, P. Moffa- Sanchez, N. Rose, P. Spooner and I. Yashayaev "Anomalously weak Labrador Sea convection and Atlantic overturning during the past 150 years", Nature 556, 227-230, 2018, doi: 10.1038/s41586-018-0007-4.
  21. Alexander-Turner R., P. Ortega, J. Robson "How robust are the surface temperature fingerprints of the Atlantic Meridional Overturning Circulation on monthly time-scales?" Geophysical Research Letters 45, 3559-3567, 2018, doi:10.1029/2017GL076759
  22. Swingedouw D., J. Mignot, Ortega P., M. Khodri, M. Menegoz, C. Cassou, V. Hanquiez, “Impact of explosive volcanic eruptions on the main climate variability modes”, Global and Planetary Change, 150, 24-45, 2017, doi:10.1016/j.gloplacha.2017.01.006.
  23. Ortega P., E. Guilyardi, D. Swingedouw, J. Mignot and S. Nguyen, “Reconstructing extreme AMOC events through nudging of the ocean surface: A perfect model approach”, Progress in Oceanography  49, 3425–3441, 2017, doi:10.1007/s00382-017-3521-4.
  24. Guillet S., C. Corona, M. Stoffel, M. Khodri, F. Lavigne, P. Ortega, N. Eckert, P.D. Sielenou, V. Daux, O.V. Churakova (Sidorova), N. Davi, J.-L. Edouard, Y, Zhang, B. H. Luckman, V. S. Myglan, J. Guiot, M. Beniston, V. Masson-Delmotte and C. Oppenheimer, “Climate response to the Samalas volcanic eruption in 1257 revealed by proxy records”; Nature Geoscience 10,123-128, 2017, doi:10.1038/ngeo2875.
  25. Hawkins E., P. Ortega, E. Suckling, A. Schurer, G. Hegerl, P. Jones, M. Joshi, T.J. Osborn, V. Masson-Delmotte, J. Mignot, P. Thorne and G.J. van Oldenborgh, “ Estimating changes in global temperature since the pre-industrial period”; BAMS 98, 1841-1856, 2017, doi:10.1175/BAMS-D-16-0007.1.​
  26. Ortega P., J. Robson, R. Sutton and M. Andrews, “ Mechanisms of decadal variability in the Labrador Sea and the wider North Atlantic in a high-resolution climate model”, Climate Dynamics 49, 2625–2647, 2017, doi:10.1007/s00382-016-3467-y.
  27. Moreno-Chamarro E., P. Ortega, F. González-Rouco and M. Montoya, “Assessing reconstruction techniques of the Atlantic Ocean circulation variability during the last millennium”; Climate Dynamics 48799819, 2017, doi:10.1007/s00382-016-3111-x.
  28. Robson J., P. Ortega and R. Sutton, “A reversal of climatic trends in the North Atlantic since 2005”; Nature Geoscience 9, 513-517, 2016, doi:10.1038/ngeo2727.
  29. Bolliet T., P. Brockmann, V. Masson-Delmotte, F. Bassinot, V. Daux, D. Genty, A. Landais, M. Lavrieux, E. Michel, P. Ortega, C. Risi, D.M. Roche, F Vimeux and C. Waelbroeck, “Water and carbon stable isotope records from natural archives: a new database and interactive online platform for data browsing, visualizing and downloading”; Climate of the Past 12, 1693-1719, 2016, doi:10.5194/cp-12-1693-2016.
  30. Mignot J., J. García-Serrano, D. Swingedouw, A. Germe, S. Nguyen, E. Guilyardi, P. Ortega and S. Ray, “Decadal predictability skill in the ocean with surface nudging”; Climate Dynamics 47, 1225-1246, 2015, doi:10.1007/s00382-015-2898-1.
  31. Masson-Delmotte V., H.C. Steen-Larsen, P. Ortega, D. Swingedouw, T. Popp, B.M. Vinther, H. Oerter, A.E. Sveinbjornsdottir, J.E .Box, S.Falourd, X. Fettweis, H. Gallée, E. Garnier, J. Jouzel, A. Landais, B. Minster, N. Paradis, A. Orsi, C. Risi, M. Werner, H. Gudlaugsdottir and J.W.C. White, “Recent changes in North West Greenland climate documented by NEEM shallow ice core data and simulations, and implications for past temperature reconstructions”. The Cryosphere 9, 1481-1504, 2015, doi: 10.5194/tc-9-1481-2015.
  32. Ortega P., J. Mignot, D. Swingedouw, F. Sevellec and E. Guilyardi, “Reconciling two alternative mechanisms behind bi-decadal variability in the North Atlantic”. Progress in Oceanography 137 Part A, 237-249, 2015,doi: 10.1016/j.pocean.2015.06.009.
  33. Ortega P., F. Lehner, D. Swingedouw, V. Masson-Delmotte, C. Raible, M. Casado and P. Yiou, “A model-tested North Atlantic Oscillation reconstruction for the past millennium”. Nature 523, 71-74, 2015, doi: 10.1038/nature14518.
  34. Zanchettin D., O. Bothe, F. Lehner, P. Ortega, D. Swingedouw and J. Jungclaus, “Reconciling reconstructed and simulated features of the winter Pacific-North-American pattern in the early 19th century”. Climate of the Past 11, 939-958, 2015, doi: 10.5194/cp-11-939-2015.
  35. Swingedouw D., P. Ortega, J. Mignot, E. Guilyardi, V. Masson-Delmotte, P. G. Butler and M. Khodri, “Bidecadal North Atlantic ocean circulation variability controlled by timing of volcanic eruptions”. Nature Communications 6, 6545, 2015, doi: 10.1038/ncomms7545.
  36. Ortega P., D. Swingedouw, V. Masson-Delmotte, C. Risi, B. Vinther, P. Yiou, R. Vautard and K. Yoshimura, “Characterising the atmospheric signals in Greenland ice cores: insights from the weather regime approach”. Climate Dynamics 43, pp 2585-2605, 2014, doi: 10.1007/s00382-014-2074-z.
  37. Casado M., P. Ortega, V. Masson-Delmotte, C. Risi, D. Swingedouw, V. Daux, D. Genty, F. Maignan, O. Solomina, B. Vinther, N. Viovy, and P. Yiou, “Impact of precipitation intermittency on NAO-temperature signals in proxy records”, Climate of the Past 9, 871-886, 2013, doi: 10.5194/cp-9-871-2013.
  38. Ortega, P., J. F. González-Rouco, M. Montoya and H. Beltrami, “Variability of the ocean heat content during the last millennium – an assessment with the ECHO-g Model”, Climate of the Past 9, 547-565, 2013, doi: 10.5194/cp-9-547-2013.
  39. Ortega, P., M. Montoya, J. F. González-Rouco, J. Mignot and S. Legutke, “Variability of the Atlantic meridional overturning circulation in the last millennium and two IPCC scenarios”, Climate Dynamics 38, 1925-1947, 2012 doi: 10.1007/s00382-011-1081-6.
  40. Ortega, P., E. Hawkins and R. T. Sutton, “Processes governing the predictability of the Atlantic Meridional Overturning Circulation in a coupled GCM”, Climate Dynamics 37, 1771–1782, 2011, doi: 10.1007/s00382-011-1025-1.

Articles in open discussion:

  • Döscher, R., M. Acosta, A. Alessandri, P. Anthoni, A. Arneth, T. Arsouze, T. Bergmann, R. Bernadello, S. Bousetta, L.-P. Caron, G. Carver, M. Castrillo, F. Catalano, I. Cvijanovic, P. Davini, E. Dekker, F. J. Doblas-Reyes, D. Docquier, P. Echevarria, U. Fladrich, R. Fuentes-Franco, M. Gröger, J. v. Hardenberg, J. Hieronymus, M. P. Karami, J.-P. Keskinen, T. Koenigk, R. Makkonen, F. Massonnet, M. Ménégoz, P. A. Miller, E. Moreno-Chamarro, L. Nieradzik, T. van Noije, P. Nolan, D. O’Donnell, P. Ollinaho, G. van den Oord, P. Ortega, O. Tintó-Prims, A. Ramos, T. Reerink, C. Rousset, Y. Ruprich-Robert, P. Le Sager, T. Schmith, R. Schrödner, F. Serva, V. Sicardi, M. Sloth Madsen, B. Smith, T. Tian, E. Tourigny, P. Uotila, M. Vancoppenolle, S. Wang, D. Wårlind, U. Willén, K. Wyser, S. Yang, X. Yepes-Arbós,  and Q. Zhang "The EC-Earth3 Earth System Model for the Climate Model Intercomparison Project 6", Geosci. Model Dev. Discuss, in review, 2021,


  • Hernández A., B. Martrat, L. Comas-Bru, C. Martin-Puertas, P. Moffa-Sánchez, E. Moreno-Chamarro, P. Ortega and D. Swingedouw, "Climatic modes of variability over the Holocene: Model-data synergies to improve future projections", PAGES Magazine 27, pp 89, 2019.
  • Ortega P. and M. Donat, "CMIP6 Model Analysis Workshop", GEWEX News, Quarter 2, pp 10, 2019.
  • Bojovic D., R. Bilbao, L.B. Díaz, M. Donat, P. Ortega, Y. Ruprich-Robert, B. Solaraju-Murali, M. Terrado, D. Verfaillie and F.J. Doblas-Reyes, "The biggest unknowns related to decadal prediction: what 50 experts think are the 5 major knowledge gaps", BAMS 100, ES255–ES259, 2019 doi:10.1175/BAMS-D-19-0190.1
  • Killbourne H., M. Klockmann, E. Moreno-Chamarro, P. Ortega, A. Romanou, M. Srokosz, Z. Szuts, K. Thirumalai, I. Hall, P. Heimbach, D. Oppo, A. Schmittner and R. Zhang, "Connecting paleo and modern oceanographic data to understand AMOC over decades to centuries", US CLIVAR Workshop Report 2017-3, pp. 1 - 30, 2017.
  • Ortega P., “Atmospheric science: Clouding the warming”; Nature Geoscience 9, 567–568, 2016, doi:10.1038/ngeo2758.
  • Ortega P., J. Robson, P. Moffa-Sanchez, D. Thornalley and D. Swingedouw, “A last millennium perspective on North Atlantic variability: exploiting synergies between models and proxy data”, Joint Issue of Clivar Exchanges/Past Global Changes Magazine 72, 61-67, 2017.
  • Goosse H., F. Klein, D. Swingedouw and P. Ortega, “Internal and forced decadal variability: lessons from the past millennium”, Joint Issue of Clivar Exchanges/Past Global Changes Magazine 72, 47-51, 2017.
  • H. Gallée, P. Ortega and H. Christian Steen-Larsen, “Rôle de la circulation atmosphérique de grande échelle”, Chapter 1.6 of the book Groenland : climat, ecologie et societe, CNRS éditions, 03/10/2016.
  • Ribes A. and P. Ortega, “Variabilité et changement du climat du Groenland au cours des deux cents dernières années”, Chapter 1.7 of the book Groenland : climat, ecologie et societe, CNRS éditions, 03/10/2016.
  • Masson-Delmotte V., P. Ortega and E. Gauthier, “Greater knowledge, better climate”, International Innovation 169, 59-61.