Nature Communications Nat Commun 2041-1723 12 2018 9 1 High climate model dependency of Pliocene Antarctic ice-sheet predictions Aisling M. Dolan Bas de Boer http://orcid.org/0000-0002-3696-6654 Jorge Bernales Daniel J. Hill http://orcid.org/0000-0001-5492-3925 Alan M. Haywood Abstract

The mid-Pliocene warm period provides a natural laboratory to investigate the long-term response of the Earth’s ice-sheets and sea level in a warmer-than-present-day world. Proxy data suggest that during the warm Pliocene, portions of the Antarctic ice-sheets, including West Antarctica could have been lost. Ice-sheet modelling forced by Pliocene climate model outputs is an essential way to improve our understanding of ice-sheets during the Pliocene. However, uncertainty exists regarding the degree to which results are model-dependent. Using climatological forcing from an international climate modelling intercomparison project, we demonstrate the high dependency of Antarctic ice-sheet volume predictions on the climate model-based forcing used. In addition, the collapse of the vulnerable marine basins of Antarctica is dependent on the ice-sheet model used. These results demonstrate that great caution is required in order to avoid making unsound statements about the nature of the Pliocene Antarctic ice-sheet based on model results that do not account for structural uncertainty in both the climate and ice sheet models.

 07 18 2018 2799 5179 1 10.1007/springer_crossmark_policy link.springer.com false 14 August 2017 21 May 2018 18 July 2018 The authors declare no competing interests. EC | European Research Council https://doi.org/10.13039/501100000781 278636 278636 https://creativecommons.org/licenses/by/4.0 https://creativecommons.org/licenses/by/4.0 10.1038/s41467-018-05179-4 20221220163059450 https://www.nature.com/articles/s41467-018-05179-4 https://www.nature.com/articles/s41467-018-05179-4.pdf https://www.nature.com/articles/s41467-018-05179-4.pdf https://www.nature.com/articles/s41467-018-05179-4 Clim. Past AM Haywood 9 191 2013 10.5194/cp-9-191-2013 Haywood, A. M. et al. Large-scale features of Pliocene climate: results from the Pliocene Model Intercomparison Project. Clim. Past 9, 191–209 (2013). Philos. Trans. R. Soc. Lond. A MPS Badger 371 20130094 2013 10.1098/rsta.2013.0094 Badger, M. P. S., Schmidt, D. N., Mackensen, A. & Pancost, R. D. High-resolution alkenone palaeobarometry indicates relatively stable pCO2 during the Pliocene (3.3–2.8 Ma). Philos. Trans. R. Soc. Lond. A 371, 20130094 (2013). Nature MA Martinez-Boti 518 49 2015 10.1038/nature14145 Martinez-Boti, M. A. et al. Plio-Pleistocene climate sensitivity evaluated using high-resolution CO2 records. Nature 518, 49–54 (2015). Nat. Geosci. ME Raymo 4 328 2011 10.1038/ngeo1118 Raymo, M. E., Mitrovica, J. X., O’Leary, M. J., DeConto, R. M. & Hearty, P. J. Departures from eustasy in Pliocene sea-level records. Nat. Geosci. 4, 328–332 (2011). Earth Planet. Sci. Lett. A Rovere 387 27 2014 10.1016/j.epsl.2013.10.030 Rovere, A. et al. The Mid-Pliocene sea-level conundrum: glacial isostasy, eustasy and dynamic topography. Earth Planet. Sci. Lett. 387, 27–33 (2014). Nature EJ Rohling 508 477 2014 10.1038/nature13230 Rohling, E. J. et al. Sea-level and deep-sea-temperature variability over the past 5.3 million years. Nature 508, 477–482 (2014). 10.1126/science.aaa4019 Dutton, A. et al. Sea-level rise due to polar ice-sheet mass loss during past warm periods. Science 349, aaa4019 (2015). Geology KG Miller 40 407 2012 10.1130/G32869.1 Miller, K. G. et al. High tide of the warm Pliocene: implications of global sea level for Antarctic deglaciation. Geology 40, 407–410 (2012). Masson-Delmotte, V. et al. In Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change (eds Stocker, T. F. et al.) Ch. 5 (Cambridge University Press, 2013). Nature T Naish 458 322 2009 10.1038/nature07867 Naish, T. et al. Obliquity-paced Pliocene West Antarctic ice sheet oscillations. Nature 458, 322–328 (2009). Paleoceanography CP Cook 29 533 2014 10.1002/2014PA002625 Cook, C. P. et al. Sea surface temperature control on the distribution of far-traveled Southern Ocean ice-rafted detritus during the Pliocene. Paleoceanography 29, 533–548 (2014). Nat. Geosci. CP Cook 6 765 2013 10.1038/ngeo1889 Cook, C. P. et al. Dynamic behaviour of the East Antarctic ice sheet during Pliocene warmth. Nat. Geosci. 6, 765–769 (2013). Earth Planet. Sci. Lett. T Williams 290 351 2010 10.1016/j.epsl.2009.12.031 Williams, T. et al. Evidence for iceberg armadas from East Antarctica in the Southern Ocean during the late Miocene and early Pliocene. Earth Planet. Sci. Lett. 290, 351–361 (2010). Nat. Commun. M Yamane 6 2015 10.1038/ncomms8016 Yamane, M. et al. Exposure age and ice-sheet model constraints on Pliocene East Antarctic ice sheet dynamics. Nat. Commun. 6, 7016 (2015). Nature D Pollard 458 329 2009 10.1038/nature07809 Pollard, D. & DeConto, R. M. Modelling West Antarctic ice sheet growth and collapse through the past five million years. Nature 458, 329–332 (2009). Clim. Past NR Golledge 13 959 2017 10.5194/cp-13-959-2017 Golledge, N. R. et al. Antarctic climate and ice-sheet configuration during the early Pliocene interglacial at 4.23 Ma. Clim. Past 13, 959–975 (2017). Geosci. Model Dev. D Pollard 5 1273 2012 10.5194/gmd-5-1273-2012 Pollard, D. & DeConto, R. M. Description of a hybrid ice sheet-shelf model, and application to Antarctica. Geosci. Model Dev. 5, 1273–1295 (2012). Geosci. Model Dev. B de Boer 7 2141 2014 10.5194/gmd-7-2141-2014 de Boer, B., Stocchi, P. & van de Wal, R. S. W. A fully coupled 3-D ice-sheet–sea-level model: algorithm and applications. Geosci. Model Dev. 7, 2141–2156 (2014). Hill, D. J., Haywood, A. M., Hindmarsh, R. C. M. & Valdes, P. J. In Deep-Time Perspectives on Climate Change: Marrying the signal from Computer Models and Biological Proxies (eds Williams, M. et al.) 517–538 (The Micropalaeontological Society Special Publications, The Geological Society, 2007). Palaeogeogr. Palaeoclimatol. Palaeoecol. AM Dolan 309 98 2011 10.1016/j.palaeo.2011.03.030 Dolan, A. M. et al. Sensitivity of Pliocene ice sheets to orbital forcing. Palaeogeogr. Palaeoclimatol. Palaeoecol. 309, 98–110 (2011). Nature RM DeConto 531 591 2016 10.1038/nature17145 DeConto, R. M. & Pollard, D. Contribution of Antarctica to past and future sea-level rise. Nature 531, 591–597 (2016). Earth Planet. Sci. Lett. D Pollard 412 112 2015 10.1016/j.epsl.2014.12.035 Pollard, D., DeConto, R. M. & Alley, R. B. Potential Antarctic Ice Sheet retreat driven by hydrofracturing and ice cliff failure. Earth Planet. Sci. Lett. 412, 112–121 (2015). Nat. Clim. Change M Mengel 4 451 2014 10.1038/nclimate2226 Mengel, M. & Levermann, A. Ice plug prevents irreversible discharge from East Antarctica. Nat. Clim. Change 4, 451–455 (2014). Geosci. Model Dev. AM Haywood 4 571 2011 10.5194/gmd-4-571-2011 Haywood, A. M. et al. Pliocene Model Intercomparison Project (PlioMIP): experimental design and boundary conditions (Experiment 2). Geosci. Model Dev. 4, 571–577 (2011). Flato, G. et al. In Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change (eds Stocker, T. F. et al.) Ch. 9 (Cambridge University Press, 2013). Stratigraphy HJ Dowsett 7 123 2010 10.29041/strat.07.2.03 Dowsett, H. J. et al. The PRISM3D paleoenvironmental reconstruction. Stratigraphy 7, 123–139 (2010). Geosci. Model Dev. AM Dolan 5 963 2012 10.5194/gmd-5-963-2012 Dolan, A. M., Koenig, S. J., Hill, D. J., Haywood, A. M. & DeConto, R. M. Pliocene Ice Sheet Modelling Intercomparison Project (PLISMIP)—experimental design. Geosci. Model Dev. 5, 963–974 (2012). Cryosphere B de Boer 9 881 2015 10.5194/tc-9-881-2015 de Boer, B. et al. Simulating the Antarctic ice sheet in the late-Pliocene warm period: PLISMIP-ANT, an ice-sheet model intercomparison project. Cryosphere 9, 881–903 (2015). Ann. Glaciol. T Sato 53 221 2012 10.3189/2012AoG60A042 Sato, T. & Greve, R. Sensitivity experiments for the Antarctic ice sheet with varied sub-ice-shelf melting rates. Ann. Glaciol. 53, 221–228 (2012). Cryosphere Discuss. J Bernales 2016 1 2016 10.5194/tc-2016-117 Bernales, J., Rogozhina, I., Greve, R. & Thomas, M. Comparison of hybrid schemes for the combination of shallow approximations in numerical simulations of the Antarctic Ice Sheet. Cryosphere 11, 247–265 (2017). J. Glaciol. RCA Hindmarsh 45 568 1999 10.1017/S0022143000001441 Hindmarsh, R. C. A. On the numerical computation of temperature in an ice-sheet. J. Glaciol. 45, 568–574 (1999). Geosci. Model Dev. FJ Bragg 5 1109 2012 10.5194/gmd-5-1109-2012 Bragg, F. J., Lunt, D. J. & Haywood, A. M. Mid-Pliocene climate modelled using the UK Hadley Centre Model: PlioMIP Experiments 1 and 2. Geosci. Model Dev. 5, 1109–1125 (2012). Geosci. Model Dev. C Stepanek 5 1221 2012 10.5194/gmd-5-1221-2012 Stepanek, C. & Lohmann, G. Modelling mid-Pliocene climate with COSMOS. Geosci. Model Dev. 5, 1221–1243 (2012). Geosci. Model Dev. NA Rosenbloom 6 549 2013 10.5194/gmd-6-549-2013 Rosenbloom, N. A., Otto-Bliesner, B. L., Brady, E. C. & Lawrence, P. J. Simulating the mid-Pliocene Warm Period with the CCSM4 model. Geosci. Model Dev. 6, 549–561 (2013). Geosci. Model Dev. C Contoux 5 903 2012 10.5194/gmd-5-903-2012 Contoux, C., Ramstein, G. & Jost, A. Modelling the mid-Pliocene Warm Period climate with the IPSL coupled model and its atmospheric component LMDZ5A. Geosci. Model Dev. 5, 903–917 (2012). Geosci. Model Dev. WL Chan 4 1035 2011 10.5194/gmd-4-1035-2011 Chan, W. L., Abe-Ouchi, A. & Ohgaito, R. Simulating the mid-Pliocene climate with the MIROC general circulation model: experimental design and initial results. Geosci. Model Dev. 4, 1035–1049 (2011). Geosci. Model Dev. Y Kamae 5 793 2012 10.5194/gmd-5-793-2012 Kamae, Y. & Ueda, H. Mid-Pliocene global climate simulation with MRI-CGCM2.3: set-up and initial results of PlioMIP Experiments 1 and 2. Geosci. Model Dev. 5, 793–808 (2012). Geosci. Model Dev. ZS Zhang 5 523 2012 10.5194/gmd-5-523-2012 Zhang, Z. S. et al. Pre-industrial and mid-Pliocene simulations with NorESM-L. Geosci. Model Dev. 5, 523–533 (2012). Cryosphere P Fretwell 7 375 2013 10.5194/tc-7-375-2013 Fretwell, P. et al. Bedmap2: improved ice bed, surface and thickness datasets for Antarctica. Cryosphere 7, 375–393 (2013). Clim. Past AM Dolan 11 403 2015 10.5194/cp-11-403-2015 Dolan, A. M. et al. Using results from the PlioMIP ensemble to investigate the Greenland Ice Sheet during the mid-Pliocene Warm Period. Clim. Past 11, 403–424 (2015). Clim. Past SJ Koenig 11 369 2015 10.5194/cp-11-369-2015 Koenig, S. J. et al. Ice sheet model dependency of the simulated Greenland Ice Sheet in the mid-Pliocene. Clim. Past 11, 369–381 (2015). Clim. Past DJ Hill 10 79 2014 10.5194/cp-10-79-2014 Hill, D. J. et al. Evaluating the dominant components of warming in Pliocene climate simulations. Clim. Past 10, 79–90 (2014). J. Geophys. Res.: Atmos. Q Yan 121 1559 2016 10.1002/2015JD023900 Yan, Q., Zhang, Z. & Wang, H. Investigating uncertainty in the simulation of the Antarctic ice sheet during the mid-Piacenzian. J. Geophys. Res.: Atmos. 121, 1559–1574 (2016). Geology J Austermann 43 927 2015 10.1130/G36988.1 Austermann, J. et al. The impact of dynamic topography change on Antarctic ice sheet stability during the mid-Pliocene warm period. Geology 43, 927–930 (2015). Geophys. Res. Lett. E Gasson 42 5372 2015 10.1002/2015GL064322 Gasson, E., DeConto, R. & Pollard, D. Antarctic bedrock topography uncertainty and ice sheet stability. Geophys. Res. Lett. 42, 5372–5377 (2015). Geology E Gasson 44 827 2016 10.1130/G38104.1 Gasson, E., DeConto, R. & Pollard, D. Modeling the oxygen isotope composition of the Antarctic ice sheet and its significance to Pliocene sea level. Geology 44, 827–830 (2016). Earth Planet. Sci. Lett. R Moucha 271 101 2008 10.1016/j.epsl.2008.03.056 Moucha, R. et al. Dynamic topography and long-term sea-level variations: there is no such thing as a stable continental platform. Earth Planet. Sci. Lett. 271, 101–108 (2008). Geology MJ Winnick 43 879 2015 10.1130/G36999.1 Winnick, M. J. & Caves, J. K. Oxygen isotope mass-balance constraints on Pliocene sea level and East Antarctic Ice Sheet stability. Geology 43, 879–882 (2015). Earth Sci. Rev. ME Raymo 177 291 2018 10.1016/j.earscirev.2017.11.022 Raymo, M. E., Kozdon, R., Evans, D., Lisiecki, L. & Ford, H. L. The accuracy of mid-Pliocene δ18O-based ice volume and sea level reconstructions. Earth Sci. Rev. 177, 291–302 (2018). Nature NR Golledge 526 421 2015 10.1038/nature15706 Golledge, N. R. et al. The multi-millennial Antarctic commitment to future sea-level rise. Nature 526, 421–425 (2015). J. Glaciol. J Feldmann 60 353 2017 10.3189/2014JoG13J093 Feldmann, J., Albrecht, T., Khroulev, C., Pattyn, F. & Levermann, A. Resolution-dependent performance of grounding line motion in a shallow model compared with a full-Stokes model according to the MISMIP3d intercomparison. J. Glaciol. 60, 353–360 (2017). Ann. Glaciol. SL Cornford 57 1 2016 10.1017/aog.2016.13 Cornford, S. L., Martin, D. F., Lee, V., Payne, A. J. & Ng, E. G. Adaptive mesh refinement versus subgrid friction interpolation in simulations of Antarctic ice dynamics. Ann. Glaciol. 57, 1–9 (2016). Clim. Past H Dowsett 12 1519 2016 10.5194/cp-12-1519-2016 Dowsett, H. et al. The PRISM4 (mid-Piacenzian) paleoenvironmental reconstruction. Clim. Past 12, 1519–1538 (2016). Clim. Past AM Haywood 12 663 2016 10.5194/cp-12-663-2016 Haywood, A. M. et al. The Pliocene Model Intercomparison Project (PlioMIP) Phase 2: scientific objectives and experimental design. Clim. Past 12, 663–675 (2016). Glob. Ecol. Biogeogr. U Salzmann 17 432 2008 10.1111/j.1466-8238.2008.00381.x Salzmann, U., Haywood, A. M., Lunt, D. J., Valdes, P. J. & Hill, D. J. A new global biome reconstruction and data-model comparison for the Middle Pliocene. Glob. Ecol. Biogeogr. 17, 432–447 (2008). Hill, D. J. Modelling Earth’s Cryosphere During Peak Pliocene Warmth. Ph.D. Thesis, University of Bristol (2009). Hutter, K. Theoretical Glaciology: Material Science of Ice and the Mechanics of Glaciers and Ice Sheets (Springer, 1983). 10.1007/978-94-009-3745-1_6 Morland, L. W. In Dynamics of the West Antarctic Ice Sheet (eds de Veen, C. J. V. & Oerlemans, J.) 99–116 (D. Reidel, 1987). Geosci. Model Dev. TJ Reerink 3 13 2010 10.5194/gmd-3-13-2010 Reerink, T. J., Kliphuis, M. A. & van de Wal, R. S. W. Mapping technique of climate fields between GCM’s and ice models. Geosci. Model Dev. 3, 13–41 (2010). 10.3133/pp1395 Snyder, J. P. Map projections—a working manual. In USGS Professional Paper 1395. Available at: https://pubs.er.usgs.gov/publication/pp1395 (USGS, 1987). Clim. Dyn. B de Boer 41 1365 2013 10.1007/s00382-012-1562-2 de Boer, B., van de Wal, R. S. W., Lourens, L. J., Bintanja, R. & Reerink, T. J. A continuous simulation of global ice volume over the past 1 million years with 3-D ice-sheet models. Clim. Dyn. 41, 1365–1384 (2013). Cryosphere R Winkelmann 5 715 2011 10.5194/tc-5-715-2011 Winkelmann, R. et al. The Potsdam Parallel Ice Sheet Model (PISM-PIK)—Part 1: model description. Cryosphere 5, 715–726 (2011). Ocean Model. A Beckmann 5 157 2003 10.1016/S1463-5003(02)00019-7 Beckmann, A. & Goosse, H. A parameterization of ice shelf–ocean interaction for climate models. Ocean Model. 5, 157–170 (2003). Ann. Glaciol. T Dunse 57 247 2011 10.3189/002214311796405979 Dunse, T., Greve, R., Schuler, T. V. & Hagen, J. O. Permanent fast flow versus cyclic surge behaviour: numerical simulations of the Austfonna ice cap, Svalbard. Ann. Glaciol. 57, 247–259 (2011). Paleoclimates I Marsiat 1 59 1994 Marsiat, I. Simulation of the Northern Hemisphere continental ice sheets over the last glacial–interglacial cycle: experiments with a latitude-longitude vertically integrated ice sheet model coupled to a zonally averaged climate model. Paleoclimates 1, 59–98 (1994). Polarforschung N Reeh 59 113 1991 Reeh, N. Parameterization of melt rate and surface temperature on the Greenland ice sheet. Polarforschung 59, 113–128 (1991). J. Glaciol. R Calov 51 173 2005 10.3189/172756505781829601 Calov, R. & Greve, R. A semi-analytical solution for the positive degree-day model with stochastic temperature variations. J. Glaciol. 51, 173–175 (2005). J. Clim. PR Holland 21 2558 2008 10.1175/2007JCLI1909.1 Holland, P. R., Jenkins, A. & Holland, D. M. The response of ice shelf basal melting to variations in ocean temperature. J. Clim. 21, 2558–2572 (2008). J. Glaciol. RJ Braithwaite 41 153 1995 10.1017/S0022143000017846 Braithwaite, R. J. Positive degree-day factors for ablation on the Greenland ice sheet studied by energy-balance modelling. J. Glaciol. 41, 153–160 (1995). Stratigraphy DJ Hill 7 111 2010 10.29041/strat.07.2.02 Hill, D. J., Dolan, A. M., Haywood, A. M., Hunter, S. J. & Stoll, D. K. Sensitivity of the Greenland Ice Sheet to Pliocene sea surface temperatures. Stratigraphy 7, 111–122 (2010).