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Este proyecto propone un cambio del rol del docente en el aula de transmisor a facilitador. Para ello, se apuesta por implantar metodologías que favorezcan el aprendizaje cooperativo en el aula y potencien el desarrollo de competencias transversales.

© 2007 by the American Geophysical Union. We are grateful to J. R. Toggweiler and J. Mignot for useful comments on the manuscript. A.L. was funded by the Gary Comer foundation, M.M. by the Ramón y Cajal Program and project CGL2005-06097/CLI of the Spanish Ministry for Science and Education., A cessation of the Atlantic meridional overturning circulation (AMOC) significantly reduces northward oceanic heat transport. In response to anomalous freshwater flux, this leads to the classic 'bipolar see-saw' pattern of northern cooling and southern warming in surface air and ocean temperatures. By contrast, as shown here in a coupled climate model, both northern and southern cooling are observed for an AMOC reduction in response to reduced wind stress in the Southern Ocean (SO). For very weak SO wind stress, not only the overturning circulation collapses, but sea ice export from the SO is strongly reduced. Consequently, sea ice extent and albedo increase in this region. The resulting cooling overcompensates the warming by the reduced northward heat transport. The effect depends continuously on changes in wind stress and is reversed for increased winds. It may have consequences for abrupt climate change, the last deglaciation and climate sensitivity to increasing atmospheric CO_2 concentration., Comer Family Foundation, Ayudas para contratos Ramón y Cajal (RYC), Ministerio de Educación y Ciencia (MEC), España, Ministerio de Economía y Competitividad (MINECO), España, Depto. de Física de la Tierra y Astrofísica, Fac. de Ciencias Físicas, TRUE, pub

© 2004 by the American Geophysical Union. This work was supported by the Research Grant 01 LG 9906 of BMBF. The work benefited from discussions with Reinhard Calov, Stefan Rahmstorf, and Sushma Prasad. The time series from GRIP and NorthGRIP were kindly provided by Sigfus Johnsen. The authors thank Hans Renssen and the anonymous Referee for their valuable comments on the manuscript., The cold climate anomaly about 8200 years ago is investigated with CLIMBER-2, a coupled atmosphere-ocean-biosphere model of intermediate complexity. This climate model simulates a cooling of about 3.6 K over the North Atlantic induced by a meltwater pulse from Lake Agassiz routed through the Hudson strait. The meltwater pulse is assumed to have a volume of 1.6 x 10^14 m^3 and a period of discharge of 2 years on the basis of glaciological modeling of the decay of the Laurentide Ice Sheet ( LIS). We present a possible mechanism which can explain the centennial duration of the 8.2 ka cold event. The mechanism is related to the existence of an additional equilibrium climate state with reduced North Atlantic Deep Water (NADW) formation and a southward shift of the NADW formation area. Hints at the additional climate state were obtained from the largely varying duration of the pulse-induced cold episode in response to overlaid random freshwater fluctuations in Monte Carlo simulations. The model equilibrium state was attained by releasing a weak multicentury freshwater flux through the St. Lawrence pathway completed by the meltwater pulse. The existence of such a climate mode appears essential for reproducing climate anomalies in close agreement with paleoclimatic reconstructions of the 8.2 ka event. The results furthermore suggest that the temporal evolution of the cold event was partly a matter of chance., Webauftritts des Bundesministeriums für Bildung und Forschung (BMBF), Alemania, Depto. de Física de la Tierra y Astrofísica, Fac. de Ciencias Físicas, TRUE, pub

© 2000 American Meteorological Society. We thank D. Schriever and M. Lautenschlager for supporting us with the simulations for the last interglacial and S.-Y. Kim for providing us with the EBM results. M. Montoya thanks also E. Zorita and S. Rahmstorf for valuable discussion, R. Voss and U. Cubasch for discussion concerning technical details of the model, and J.-S. von Storch for her help in the analysis of the ocean data. Finally, we thank J. Kutzbach and another anonymous reviewer for their valuable comments. M. Montoya was supported by a grant of the Dirección General de Investigación Científica y Técnica (Spain). H. von Storch was supported by EU Project MILLENIA. T. J. Crowley was supported by National Science Foundation Grant ATM-9529109., The ECHAM-1 T21/LSG coupled ocean-atmosphere general circulation model (GCM) is used to simulate climatic conditions at the last interglacial maximum (Eemian. 125 kyr BP). The results reflect thc expected surface temperature changes (with respect to the control run) due to the amplification (reduction) of the seasonal cycle of insolation in the Northern (Southern) Hemisphere. A number of simulated features agree with previous results from atmospheric GCM simulations e.g. intensified summer southwest monsoons) except in the Northern Hemisphere poleward of 30 degrees N. where dynamical feedback, in the North Atlantic and North Pacific increase zonal temperatures about 1 degrees C above what would be predicted from simple energy balance considerations. As this is the same area where most of the terrestrial geological data originate, this result suggests that previous estimates of Eemian global average temperature might have been biased by sample distribution. This conclusion is supported by the fact that the estimated global temperature increase of only 0.3 degrees C greater than the control run ha, been previously shown to be consistent a with CLIMAP sea surface temperature estimates. Although the Northern Hemisphere summer monsoon is intensified. globally averaged precipitation over land is within about 1% of the present, contravening some geological inferences bur not the deep-sea delta(13)C estimates of terrestrial carbon storage changes. Winter circulation changes in the northern Arabian Sea. driven by strong cooling on land, are as large as summer circulation changes that are the usual focus of interest, suggesting that interpreting variations in the Arabian Sea. sedimentary record solely in terms of the summer monsoon response could sometimes lead to errors. A small monsoonal response over northern South America suggests that interglacial paleotrends in this region were not just due to El Nino variations., Dirección General de Investigación Científica y Técnica (DGICYT), España, MILLENIA Project (UE), National Science Foundation (NSF), Unión Europea (UE), Depto. de Física de la Tierra y Astrofísica, Fac. de Ciencias Físicas, TRUE, pub

© 2005 by the American Geophysical Union. Artículo firmado por 18 autores. We are grateful to Cathy Johnson, Bill Hurlin and Mike Spelman for comments on the manuscript, to Frank Koesters for discussion, to Jianjun Yin for his help in preparing the paper, to Oleg Saenko and an anonymous referee for their reviews, and to our respective funding agencies for support., As part of the Coupled Model Intercomparison Project, integrations with a common design have been undertaken with eleven different climate models to compare the response of the Atlantic thermohaline circulation ( THC) to time-dependent climate change caused by increasing atmospheric CO2 concentration. Over 140 years, during which the CO2 concentration quadruples, the circulation strength declines gradually in all models, by between 10 and 50%. No model shows a rapid or complete collapse, despite the fairly rapid increase and high final concentration of CO2. The models having the strongest overturning in the control climate tend to show the largest THC reductions. In all models, the THC weakening is caused more by changes in surface heat flux than by changes in surface water flux. No model shows a cooling anywhere, because the greenhouse warming is dominant., Depto. de Física de la Tierra y Astrofísica, Fac. de Ciencias Físicas, TRUE, pub

© 1998 by the American Geophysical Union. We thank D. Schriever for supporting us with the simulations for the last interglacial and M. Lautenschlager for helping us to set up the experiment. M. Montoya thanks also E. Zorita, V. Kharin, S. Lorenz, and V. Ocafia for advice and discussion. Finally, we thank the reviewers (C. Covey, P. Fawcett, and G. Vailis) for their valuable comments. M. Montoya was supported by a grant of the Dirección General de Investigación Científica y Técnica (Spain). T. J. Crowley was supported by National Science Foundation grant ATM-9529109. H. yon Storch was supported by BMBF grant 07VKV01/1., The last interglacial (Eemian, 125,000 years ago) has generally been considered the warmest time period in the last 200,000 years and thus sometimes been used as a reference for greenhouse projections. Herein we report results from a coupled ocean-atmosphere climate model of the surface temperature response to changes in the radiative forcing at the last interglacial. Although the model generates the expected summer warming in the northern hemisphere, winter cooling of a comparable magnitude occurs over North Africa and tropical Asia. The global annual mean temperature for the Eemian run is 0.3 degrees C cooler than the control run. Validation of simulated sea surface temperatures (SSTs) against reconstructed SSTs supports this conclusion and also the assumption that the flux correction, fitted for the present state, operates satisfactorily for modest perturbations. Our results imply that contrary to conventional expectations, Eemian global temperatures may already have been reached by the mid 20th century., Dirección General de Investigación Científica y Técnica (DGICYT), España, National Science Foundation (NSF), Bundesministeriums für Bildung und Forschung (BMBF), Alemania, Depto. de Física de la Tierra y Astrofísica, Fac. de Ciencias Físicas, TRUE, pub

© 2007 by the American Geophysical Union. We are grateful to Miguel A. M. Maqueda for contributing many relevant ideas and for many discussions from which the paper has gained strongly. We are as well indebted to Andrey Ganopolski for many useful comments and suggestions that have improved this manuscript. The paper was considerably improved by the remarks of Wilbert Weijer and two anonymous reviewers. The authors appreciate the support of several funding agencies (T.K., German Federal Ministry for Education, Science and Research through the project ‘‘Integration’’; A.G. and M.H., McDonnell Foundation; M.M., Spanish Ministry for Science and Education through the Ramón y Cajal Program and project CGL2005-06097/CLI; and A.L., Gary Comer Foundation). [135] The Editor responsible for this paper was Henk Dijkstra. He thanks technical reviewer Wilbert Weijer and two anonymous reviewers., Because of its relevance for the global climate the Atlantic meridional overturning circulation (AMOC) has been a major research focus for many years. Yet the question of which physical mechanisms ultimately drive the AMOC, in the sense of providing its energy supply, remains a matter of controversy. Here we review both observational data and model results concerning the two main candidates: vertical mixing processes in the ocean's interior and wind-induced Ekman upwelling in the Southern Ocean. In distinction to the energy source we also discuss the role of surface heat and freshwater fluxes, which influence the volume transport of the meridional overturning circulation and shape its spatial circulation pattern without actually supplying energy to the overturning itself in steady state. We conclude that both wind-driven upwelling and vertical mixing are likely contributing to driving the observed circulation. To quantify their respective contributions, future research needs to address some open questions, which we outline., Bundesministerium für Bildung und Forschung (BMBF), Alemania = Ministerio de Educación, Ciencia e Investigación, McDonnell Foundation, Ayudas para contratos Ramón y Cajal (RYC), MINECO, España, Gary Comer Foundation, Ministerio de Economía y Competitividad (MINECO), España, Ministerio de Educación y Ciencia (MEC), España, Depto. de Física de la Tierra y Astrofísica, Fac. de Ciencias Físicas, TRUE, pub

© 2008 by the American Geophysical Union. M. M. was funded by the Ramón y Cajal Program and project CGL2005-06097/CLI of the Spanish Ministry for Science and Education. We are grateful to J. R. Toggweiler for constructive criticism which has improved this manuscript., Using a coupled model of intermediate complexity the sensitivity of the last glacial maximum (LGM) Atlantic meridional overturning circulation (AMOC) to the strength of surface wind-stress is investigated. A threshold is found below which North Atlantic deep water formation (DWF) takes place south of Greenland and the AMOC is relatively weak. Above this threshold, DWF occurs north of the Greenland-Scotland ridge, leading to a vigorous AMOC. This nonlinear behavior is explained through enhanced salt transport by the wind-driven gyre circulation and the overturning itself. Both pattern and magnitude of the Nordic Sea's temperature difference between strong and weak AMOC states are consistent with those reconstructed for abrupt climate changes of the last glacial period. Our results thus point to a potentially relevant role of surface winds in these phenomena., Ayudas para contratos Ramón y Cajal (RYC), MINECO, Ministerio de Educación y Ciencia (MEC), España, Ministerio de Economía y Competitividad (MINECO), España, Depto. de Física de la Tierra y Astrofísica, Fac. de Ciencias Físicas, TRUE, pub

© Author(s) 2013. This work is distributed under the Creative Commons Attribution 3.0 License. This work has been possible thanks to the funding by the MCINN projects CGL2005-06097 and CGL2008-06558-C02-C01/CLI, and the MARM project 200800050084028. The manuscript was significantly improved thanks to helpful and insightful comments of four anonymous reviewers. We are grateful to A. Grinsted and S. Jevrejeva for making the MatLab wavelet coherence package and their global sea level reconstructions available, and to A. Kemp for kindly sharing the data from North Carolina with us. We would also like to thank G. Sgubin for interesting discussions and to I. Fast for providing us with the extended FOR1 data.The publication of this article is financed by CNRS-INSU., Studies addressing climate variability during the last millennium generally focus on variables with a direct influence on climate variability, like the fast thermal response to varying radiative forcing, or the large-scale changes in atmospheric dynamics (e. g. North Atlantic Oscillation). The ocean responds to these variations by slowly integrating in depth the upper heat flux changes, thus producing a delayed influence on ocean heat content (OHC) that can later impact low frequency SST (sea surface temperature) variability through reemergence processes. In this study, both the externally and internally driven variations of the OHC during the last millennium are investigated using a set of fully coupled simulations with the ECHO-G (coupled climate model ECHAMA4 and ocean model HOPE-G) atmosphere-ocean general circulation model (AOGCM). When compared to observations for the last 55 yr, the model tends to overestimate the global trends and underestimate the decadal OHC variability. Extending the analysis back to the last one thousand years, the main impact of the radiative forcing is an OHC increase at high latitudes, explained to some extent by a reduction in cloud cover and the subsequent increase of short-wave radiation at the surface. This OHC response is dominated by the effect of volcanism in the preindustrial era, and by the fast increase of GHGs during the last 150 yr. Likewise, salient impacts from internal climate variability are observed at regional scales. For instance, upper temperature in the equatorial Pacific is controlled by ENSO (El Nino Southern Oscillation) variability from interannual to multidecadal timescales. Also, both the Pacific Decadal Oscillation (PDO) and the Atlantic Multidecadal Oscillation (AMO) modulate intermittently the interdecadal OHC variability in the North Pacific and Mid Atlantic, respectively. The NAO, through its influence on North Atlantic surface heat fluxes and convection, also plays an important role on the OHC at multi, Ministerio de Ciencia e Innovación (MCINN), España, Ministerio de Medio Ambiente, Medio Rural y Marino (MARM), España, Centre national de la recherche scientifique CNRS-INSU, Depto. de Física de la Tierra y Astrofísica, Fac. de Ciencias Físicas, TRUE, pub

© 2006 American Meteorological Society. Artículo firmado por 23 autores. We wish to thank T. Delworth, M. Harrison, and J. Russell for useful comments that improved earlier versions of this manuscript. We also thank two anonymous reviewers for their reviews, and our respective funding agencies for support., The Atlantic thermohaline circulation (THC) is an important part of the earth's climate system. Previous research has shown large uncertainties in simulating future changes in this critical system. The simulated THC response to idealized freshwater perturbations and the associated climate changes have been intercompared as an activity of World Climate Research Program (WCRP) Coupled Model Intercomparison Project/Paleo-Modeling Intercomparison Project (CMIP/PMIP) committees. This intercomparison among models ranging from the earth system models of intermediate complexity (EMICs) to the fully coupled atmosphere-ocean general circulation models (AOGCMs) seeks to document and improve understanding of the causes of the wide variations in the modeled THC response. The robustness of particular simulation features has been evaluated across the model results. In response to 0.1-Sv (1 Sv equivalent to 10^6 ms^3 s^-1) freshwater input in the northern North Atlantic, the multimodel ensemble mean THC weakens by 30% after 100 yr. All models simulate sonic weakening of the THC, but no model simulates a complete shutdown of the THC. The multimodel ensemble indicates that the surface air temperature could present a complex anomaly pattern with cooling south of Greenland and warming over the Barents and Nordic Seas. The Atlantic ITCZ tends to shift southward. In response to 1.0-Sv freshwater input, the THC switches off rapidly in all model simulations. A large cooling occurs over the North Atlantic. The annual mean Atlantic ITCZ moves into the Southern Hemisphere. Models disagree in terms of the reversibility of the THC after its shutdown. In general, the EMICs and AOGCMs obtain similar THC responses and climate changes with more pronounced and sharper patterns in the AOGCMs., Depto. de Física de la Tierra y Astrofísica, Fac. de Ciencias Físicas, TRUE, pub

Rate-induced tipping (R-tipping) describes the fact that, for multistable dynamic systems, an abrupt transition can take place not only because of the forcing magnitude, but also because of the forcing rate. In the present work, we demonstrate through the case study of a piecewise-linear oscillator (PLO), that increasing the rate of forcing can make the system tip in some cases but might also prevent it from tipping in others. This counterintuitive effect is further called non-monotonous R-tipping (NMRT) and has already been observed in recent studies. We show that, in the present case, the reason for NMRT is the peak synchronisation of oscillatory responses operating on different time scales. We further illustrate that NMRT can be observed even in the presence of additive white noise of intermediate amplitude. Finally, NMRT is also observed on a van-der-Pol oscillator with an unstable limit cycle, suggesting that this effect is not limited to systems with a discontinuous right-hand side such as the PLO. This insight might be highly valuable, as the current research on tipping elements is shifting from an equilibrium to a dynamic perspective while using models of increasing complexity, in which NMRT might be observed but hard to understand.

© Author(s) 2021. The authors acknowledge funding received from the European Commission’s H2020 Research Infrastructures and Spanish Ministry of Science and Innovation project RIMA. Alexander Robinson was supported by the Ramón y Cajal program of the Spanish Ministry for Science, Innovation and Universities. Simulations were performed in EOLO, the HPC of Climate Change of the International Campus of Excellence of Moncloa, funded by MECD and MICINN. We thank Ilaria Tabone for helpful discussions. Finally, we are also grateful to the reviewers and editor for helpful comments, which led to considerable improvements of the paper. This research has been supported by the European Commission, H2020 Research Infrastructures (TiPES contribution no. 23 (grant no. 820970)), the Spanish Ministry of Science and Innovation (project RIMA (grant no. CGL2017-85975-R)), and the Ramón y Cajal Programme of the Spanish Ministry for Science, Innovation and Universities (grant no. RYC-2016-20587)., Little is known about the distribution of ice in the Antarctic Ice Sheet (AIS) during the Last Glacial Maximum (LGM). Whereas marine and terrestrial geological data indicate that the grounded ice advanced to a position close to the continental-shelf break, the total ice volume is unclear. Glacial boundary conditions are potentially important sources of uncertainty, in particular basal friction and climatic boundary conditions. Basal friction exerts a strong control on the large-scale dynamics of the ice sheet and thus affects its size and is not well constrained. Glacial climatic boundary conditions determine the net accumulation and ice temperature and are also poorly known. Here we explore the effect of the uncertainty in both features on the total simulated ice storage of the AIS at the LGM. For this purpose we use a hybrid ice sheet shelf model that is forced with different basal drag choices and glacial background climatic conditions obtained from the LGM ensemble climate simulations of the third phase of the Paleoclimate Modelling Intercomparison Project (PMIP3). Overall, we find that the spread in the simulated ice volume for the tested basal drag parameterizations is about the same range as for the different general circulation model (GCM) forcings (4 to 6 m sea level equivalent). For a wide range of plausible basal friction configurations, the simulated ice dynamics vary widely but all simulations produce fully extended ice sheets towards the continental-shelf break. More dynamically active ice sheets correspond to lower ice volumes, while they remain consistent with the available constraints on ice extent. Thus, this work points to the possibility of an AIS with very active ice streams during the LGM. In addition, we find that the surface boundary temperature field plays a crucial role in determining the ice extent through its effect on viscosity. For ice sheets of a similar extent and comparable dynamics, we find that the precipitation field determines th, Unión Europea. Horizonte 2020, Ministerio de Ciencia e Innovación (MICINN), Depto. de Física de la Tierra y Astrofísica, Fac. de Ciencias Físicas, TRUE, pub

© Author(s) 2020. We would like to thank Mahé Perrette, Christophe Dumas, Gunter Leguy and Bill Lipscomb for valuable discussions about model design that improved Yelmo, Akira Nishida for help with Lis, and Ilaria Tabone and Javier Blasco for extensive model testing at intermediate development points. We are also grateful to the reviewers for helpful comments. This research has been supported by the Spanish Ministry of Science and Innovation project RIMA (grant no. CGL2017-85975-R). Alexander Robinson was funded by the Ramón y Cajal Programme of the Spanish Ministry for Science, Innovation and Universities (grant no. RYC-2016-20587). Heiko Goelzer has received funding from the program of the Netherlands Earth System Science Centre (NESSC), financially supported by the Dutch Ministry of Education, Culture and Science (OCW) (grant no. 024.002.001). Ralf Greve was supported by the Japan Society for the Promotion of Science (JSPS) KAKENHI (grant nos. JP16H02224, JP17H06104 and JP17H06323), by the Japanese Ministry of Education, Culture, Sports, Science and Technology (MEXT) through the Arctic Challenge for Sustainability (ArCS) project, and through the Arctic Challenge for Sustainability (ArCS) project (program grant no. JPMXD1300000000)., We describe the physics and features of the icesheet model Yelmo, an open-source project intended for collaborative development. Yelmo is a thermomechanical model, solving for the coupled velocity and temperature solutions of an ice sheet simultaneously. The ice dynamics are currently treated via a “hybrid” approach combining the shallow-ice and shallow-shelf/shelfy-stream approximations, which makes Yelmo an apt choice for studying a wide variety of problems. Yelmo’s main innovations lie in its flexible and user-friendly infrastructure, which promotes portability and facilitates long-term development. In particular, all physics subroutines have been designed to be self-contained, so that they can be easily ported from Yelmo to other models, or easily replaced by improved or alternate methods in the future. Furthermore, hard-coded model choices are eschewed, replaced instead with convenient parameter options that allow the model to be adapted easily to different contexts. We show results for different ice-sheet benchmark tests, and we illustrate Yelmo’s performance for the Antarctic ice sheet., Ministerio de Ciencia e Innovación (MICINN), the Netherlands Earth System Science Centre (NESSC), the Dutch Ministry of Education, Culture and Science (OCW), the Japan Society for the Promotion of Science (JSPS) program KAKENHI, the Japanese Ministry of Education, Culture, Sports, Science and Technology (MEXT) ) through the Arctic Challenge for Sustainability (ArCS), Depto. de Física de la Tierra y Astrofísica, Fac. de Ciencias Físicas, TRUE, pub

© Author(s) 2019. This work was funded by the Spanish Ministerio de Economía y Competitividad (MINECO) through project MOCCA (Modelling Abrupt Climate Change, grant no. CGL2014- 59384-R). Rubén Banderas was funded by a PhD thesis grant from the Universidad Complutense de Madrid. Alexander Robinson is funded by the Marie Curie Horizon 2020 project CONCLIMA (grant no. 703251). Part of the computations undertaken in this work were performed in EOLO, the HPC of Climate Change of the International Campus of Excellence of Moncloa, funded by MECD and MICINN. This is a contribution to CEI Moncloa. We are grateful to Catherine Ritz for providing the GRISLI code., The last glacial period (LGP; ca. 110–10 kyr BP) was marked by the existence of two types of abrupt climatic changes, Dansgaard–Oeschger (DO) and Heinrich (H) events. Although the mechanisms behind these are not fully understood, it is generally accepted that the presence of ice sheets played an important role in their occurrence. While an important effort has been made to investigate the dynamics and evolution of the Laurentide ice sheet (LIS) during this period, the Eurasian ice sheet (EIS) has not received much attention, in particular from a modeling perspective. However, meltwater discharge from this and other ice sheets surrounding the Nordic seas is often implied as a potential cause of ocean instabilities that lead to glacial abrupt climate changes. Thus, a better comprehension of the evolution of the EIS during the LGP is important to understand its role in glacial abrupt climate changes. Here we investigate the response of the EIS to millennial-scale climate variability during the LGP. We use a hybrid, three-dimensional, thermomechanical ice-sheet model that includes ice shelves and ice streams. The model is forced off-line via a novel perturbative approach that, as opposed to conventional methods, clearly differentiates between the spatial patterns of millennial-scale and orbital-scale climate variability. Thus, it provides a more realistic treatment of the forcing at millennial timescales. The effect of both atmospheric and oceanic variations are included. Our results show that the EIS responds with enhanced ice discharge in phase with interstadial warming in the North Atlantic when forced with surface ocean temperatures. Conversely, when subsurface ocean temperatures are used, enhanced ice discharge occurs both during stadials and at the beginning of the interstadials. Separating the atmospheric and oceanic effects demonstrates the major role of the ocean in controlling the dynamics of the EIS on millennial timescales. While the atmospheric forcing alon, Unión Europea. H2020, Ministerio de Economía y Competitividad (MINECO), Universidad Complutense de Madrid, Depto. de Física de la Tierra y Astrofísica, Fac. de Ciencias Físicas, TRUE, pub

© Author(s) 2019. The work was supported by the Spanish Ministry of Science and Innovation in the framework of the project MOCCA (Modelling Abrupt Climate Change, grant no. CGL2014- 59384-R). Ilaria Tabone is funded by the Spanish National Programme for the Promotion of Talent and Its Employability through grant no. BES-2015-074097. Alexander Robinson is funded by the Ramón y Cajal Programme of the Spanish Ministry for Science, Innovation and Universities. The model simulations were carried out in the HPC of Climate Change of the International Campus of Excellence of Moncloa (EOLO), supported by MECD and MICINN. Finally, we are thankful to Catherine Ritz for providing the original model GRISLI., Temperature reconstructions from Greenland icesheet (GrIS) ice cores indicate the occurrence of more than 20 abrupt warmings during the last glacial period (LGP) known as Dansgaard-Oeschger (D-O) events. Although their ultimate cause is still debated, evidence from both proxy data and modelling studies robustly links these to reorganisations of the Atlantic Meridional Overturning Circulation (AMOC). During the LGP, the GrIS expanded as far as the continental shelf break and was thus more directly exposed to oceanic changes than in the present. Therefore oceanic temperature fluctuations on millennial timescales could have had a non-negligible impact on the GrIS. Here we assess the effect of millennial-scale oceanic variability on the GrIS evolution from the last interglacial to the present day. To do so, we use a three-dimensional hybrid ice-sheet–shelf model forced by subsurface oceanic temperature fluctuations, assumed to increase during D-O stadials and decrease during D-O interstadials. Since in our model the atmospheric forcing follows orbital variations only, the increase in total melting at millennial timescales is a direct result of an increase in basal melting. We show that the GrIS evolution during the LGP could have been strongly influenced by oceanic changes on millennial timescales, leading to oceanically induced icevolume contributions above 1 m sea level equivalent (SLE). Also, our results suggest that the increased flux of GrIS icebergs as inferred from North Atlantic proxy records could have been triggered, or intensified, by peaks in melting at the base of the ice shelves resulting from increasing subsurface oceanic temperatures during D-O stadials. Several regions across the GrIS could thus have been responsible for ice mass discharge during D-O events, opening the possibility of a non-negligible role of the GrIS in oceanic reorganisations throughout the LGP., Ministerio de Ciencia e Innovación (MICINN), Spanish National Programme for the Promotion of Talent and Its Employability, Ramón y Cajal Programme of the Spanish Ministry for Science, Innovation and Universities, HPC of Climate Change of the International Campus of Excellence of Moncloa (EOLO), supported by MECD and MICINN, Depto. de Física de la Tierra y Astrofísica, Fac. de Ciencias Físicas, TRUE, pub

© Author(s) 2019. The model simulations were performed in the HPC of Climate Change of the International Campus of Excellence of Moncloa (EOLO), supported by MECD and MICINN. We are grateful to two anonymous referees, Kerim Nisancioglu and the handling editor Andreas Vieli for their valuable help in improving this work. Also, we are thankful to Catherine Ritz for providing the original GRISLI model. This research has been supported by the Spanish Ministry of Science and Innovation (grant nos. MOCCA (CGL2014-59384-R), RIMA (CGL2017-85975-R)). Ilaria Tabone was funded by the Spanish National Programme for the Promotion of Talent and Its Employability (grant no. BES-2015-074097). Alexander Robinson was funded by the Ramón y Cajal Programme of the Spanish Ministry for Science, Innovation and Universities (grant no. RYC-2016-20587)., The Northeast Greenland Ice Stream (NEGIS) has been suffering a significant ice mass loss during the last decades. This is partly due to increasing oceanic temperatures in the subpolar North Atlantic, which enhance submarine basal melting and mass discharge. This demonstrates the high sensitivity of this region to oceanic changes. In addition, a recent study suggested that the NEGIS grounding line was 20–40 km behind its present-day location for 15 ka during Marine Isotope Stage (MIS) 3. This is in contrast with Greenland temperature records indicating cold atmospheric conditions at that time, expected to favour ice-sheet expansion. To explain this anomalous retreat a combination of atmospheric and external forcings has been invoked. Yet, as the ocean is found to be a primary driver of the ongoing retreat of the NEGIS glaciers, the effect of past oceanic changes in their paleo evolution cannot be ruled out and should be explored in detail. Here we investigate the sensitivity of the NEGIS to the oceanic forcing during the last glacial period using a three-dimensional hybrid ice-sheet–shelf model. We find that a sufficiently high oceanic forcing could account for a NEGIS ice-margin retreat of several tens of kilometres, potentially explaining the recently proposed NEGIS groundingline retreat during Marine Isotope Stage 3., Ministerio de Ciencia e Innovación (MICINN), Ministerio de Educación, Cultura y Deporte (MECD), Ministerio de Ciencia e Innovación (MICINN)/Programa Ramón y Cajal, Depto. de Física de la Tierra y Astrofísica, Fac. de Ciencias Físicas, TRUE, pub

Assessing the response of the Greenland Ice Sheet (GrIS) to climate variations is crucial to understand its past and constrain its future evolution under a changing climate. On one hand, the evidence of atmospheric warming observed since the last century has strongly demanded a major understanding of the sensitivity of the GrIS to atmospheric temperature variations, leading to extensive investigation of this topic in the past. On the other hand, only recent evidence connecting GrIS mass loss to warming North Atlantic waters has driven the attention to the potential role of a changing ocean on the GrIS evolution, an aspect that has been overlooked for a long time. Starting from this evidence, several studies have been dedicated to understanding the interactions between the current GrIS evolution and the surrounding ocean. However, although we are now aware that the ocean plays a non-negligible role in shaping the configuration of the present-day GrIS, many uncertainties remain about its role in the past...

Assessing the response of the Greenland Ice Sheet (GrIS) to climate variations is crucial to understand its past and constrain its future evolution under a changing climate. On one hand, the evidence of atmospheric warming observed since the last century has strongly demanded a major understanding of the sensitivity of the GrIS to atmospheric temperature variations, leading to extensive investigation of this topic in the past. On the other hand, only recent evidence connecting GrIS mass loss to warming North Atlantic waters has driven the attention to the potential role of a changing ocean on the GrIS evolution, an aspect that has been overlooked for a long time. Starting from this evidence, several studies have been dedicated to understanding the interactions between the current GrIS evolution and the surrounding ocean. However, although we are now aware that the ocean plays a non-negligible role in shaping the configuration of the present-day GrIS, many uncertainties remain about its role in the past..., Comprender la respuesta del manto de hielo de Groenlandia (del ingles, GreenlandIce Sheet, GrIS) a las variaciones del clima es crucial para entender la evolucion pasada de dicho manto así como para constreñir su evolucion futura en un clima cambiante. Por un lado, la evidencia del calentamiento global observado desde el siglo pasado ha exigido una mejor comprension de la sensibilidad del GrIS frente a las variaciones de la temperatura del aire, lo que ha llevado a investigar ampliamente este asunto en el pasado. Por otra parte, recientemente las observaciones han permitido relacionar la perdida masiva de hielo del GrIS con el calentamiento del Atlantico Norte. Ello ha puesto el foco en el posible papel del oceano en la evolucion del GrIS, aspecto que se ha pasado por alto durante mucho tiempo. Desde entonces se ha hecho un esfuerzo importante por tratar de comprender mejor las interacciones entre el GrIS y el oceano en la actualidad. Sin embargo, aunque ahora somos conscientes de que el oceano desempeña un papel importante en la configuracion actual del GrIS, subsisten todavía incertidumbres importantes acerca de su papel en el pasado...

© Author(s) 2018. This work is distributed under the Creative Commons Attribution 4.0 License. We would like to thank Catherine Ritz for providing the original model GRISLI and Rubén Banderas for helping initially with the model. This work was funded by the Spanish Ministry of Science and Innovation under the project MOCCA (Modelling Abrupt Climate Change, grant no. CGL2014-59384-R). Ilaria Tabone is funded by the Spanish National Programme for the Promotion of Talent and Its Employability (grant no. BES-2015-074097). Alexander Robinson is funded by the Marie Curie Horizon2020 project CONCLIMA (grant no. 703251). All of these simulations were performed in EOLO, the HPC of Climate Change of the International Campus of Excellence of Moncloa, funded by MECD and MICINN., Observations suggest that during the last decades the Greenland Ice Sheet (GrIS) has experienced a gradually accelerating mass loss, in part due to the observed speed-up of several of Greenland's marine-terminating glaciers. Recent studies directly attribute this to warming North Atlantic temperatures, which have triggered melting of the outlet glaciers of the GrIS, grounding-line retreat and enhanced ice discharge into the ocean, contributing to an acceleration of sea-level rise. Reconstructions suggest that the influence of the ocean has been of primary importance in the past as well. This was the case not only in interglacial periods, when warmer climates led to a rapid retreat of the GrIS to land above sea level, but also in glacial periods, when the GrIS expanded as far as the continental shelf break and was thus more directly exposed to oceanic changes. However, the GrIS response to palaeo-oceanic variations has yet to be investigated in detail from a mechanistic modelling perspective. In this work, the evolution of the GrIS over the past two glacial cycles is studied using a three-dimensional hybrid ice-sheet-shelf model. We assess the effect of the variation of oceanic temperatures on the GrIS evolution on glacial-interglacial timescales through changes in submarine melting. The results show a very high sensitivity of the GrIS to changing oceanic conditions. Oceanic forcing is found to be a primary driver of GrIS expansion in glacial times and of retreat in interglacial periods. If switched off, palaeo-atmospheric variations alone are not able to yield a reliable glacial configuration of the GrIS. This work therefore suggests that considering the ocean as an active forcing should become standard practice in palaeo-ice-sheet modelling., Unión Europea. H2020, Ministerio de Ciencia e Innovación (MICINN), Ministerio de Educación, Cultura y Deporte (MECD), Depto. de Física de la Tierra y Astrofísica, Fac. de Ciencias Físicas, TRUE, pub

©The Author(s) 2017. We would like to thank M. Perrette for support concerning statistics and R. Greve for providing the ice sheet model SICOPOLIS. A. R. was funded by the Marie Curie 7th framework programme project EURICE (European Ice Sheet Model Initiative, Grant PIEF-GA-2012-331835) and is funded currently by the Spanish Ministerio de Economía y Competitividad project MOCCA (Modelling Abrupt Climate Change, Grant CGL2014-59384-R). R. C. was funded by the Leibniz Association grant SAW-2014-PIK-1 and is now funded by the Bundesministerium fur Bildung und Forschung (BMBF) grants PalMod-1.1-TP5 and PalMod-1.3-TP4., Palaeo data suggest that Greenland must have been largely ice free during Marine Isotope Stage 11 (MIS-11). However, regional summer insolation anomalies were modest during this time compared to MIS-5e, when the Greenland ice sheet likely lost less volume. Thus it remains unclear how such conditions led to an almost complete disappearance of the ice sheet. Here we use transient climate-ice sheet simulations to simultaneously constrain estimates of regional temperature anomalies and Greenland's contribution to the MIS-11 sea-level highstand. We find that Greenland contributed 6.1m (3.9-7.0 m, 95% credible interval) to sea level, similar to 7 kyr after the peak in regional summer temperature anomalies of 2.8 degrees C (2.1-3.4 degrees C). The moderate warming produced a mean rate of mass loss in sea-level equivalent of only around 0.4m per kyr, which means the long duration of MIS-11 interglacial conditions around Greenland was a necessary condition for the ice sheet to disappear almost completely., Unión Europea. FP7, Ministerio de Economía y Competitividad (MINECO), Leibniz Association, Bundesministerium fur Bildung und Forschung (BMBF), Depto. de Física de la Tierra y Astrofísica, Fac. de Ciencias Físicas, TRUE, pub

© 2017 Springer International Publishing AG. Open access funding provided by Max Planck society (Max Planck Institute for Meteorology). We are grateful to David Lund for providing the data of the Florida Current reconstruction. We also thank Jöel Hirschi for feedback relating the theory and Fig. 2. We acknowledge the PalMA group for technical support and for hosting the first author during a period of time when some of these ideas where developed. We thank the valuable comments from Johann H. Jungclaus and Davide Zanchettin as well. Dallas Murphy, Jochem Marotzke, and participants in the workshop Advanced Scientific Writing at the Max Planck Institute for Meteorology are thanked for comments on draft versions of the manuscript. We also thank the three anonymous reviewers for their constructive comments and reviews. Primary data and scripts used in the analysis and other supplementary information that may be useful in reproducing this work can be obtained from the authors upon request., We assess the use of the meridional thermal-wind transport estimated from zonal density gradients to reconstruct the oceanic circulation variability during the last millennium in a forced simulation with the ECHO-G coupled climate model. Following a perfect-model approach, model-based pseudo-reconstructions of the Atlantic meridional overturning circulation (AMOC) and the Florida Current volume transport (FCT) are evaluated against their true simulated variability. The pseudo-FCT is additionally verified as proxy for AMOC strength and compared with the available proxy-based reconstruction. The thermal-wind component reproduces most of the simulated AMOC variability, which is mostly driven by internal climate dynamics during the preindustrial period and by increasing greenhouse gases afterwards. The pseudo-reconstructed FCT reproduces well the simulated FCT and reasonably well the variability of the AMOC strength, including the response to external forcing. The pseudo-reconstructed FCT, however, underestimates/overestimates the simulated variability at deep/shallow levels. Density changes responsible for the pseudo-reconstructed FCT are mainly driven by zonal temperature differences; salinity differences oppose but play a minor role. These results thus support the use of the thermal-wind relationship to reconstruct the oceanic circulation past variability, in particular at multidecadal timescales. Yet model-data comparison highlights important differences between the simulated and the proxy-based FCT variability. ECHO-G simulates a prominent weakening in the North Atlantic circulation that contrasts with the reconstructed enhancement. Our model results thus do not support the reconstructed FC minimum during the Little Ice Age. This points to a failure in the reconstruction, misrepresented processes in the model, or an important role of internal ocean dynamics., Max Planck society (Max Planck Institute for Meteorology), Depto. de Física de la Tierra y Astrofísica, Fac. de Ciencias Físicas, TRUE, pub