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Copyright 2006 by the American Geophysical Union. We thank two anonymous reviewers and B. Stevens for comments. This work was partially funded by the EUproject SO&P, projects REN2002-04584-C04-CLI and CGL2005-06097 of the spanish MEC and in Canada by NSERC, CFCAS and AIF., A heat-conduction forward model driven by ground surface temperature from three 1000-year climate simulations with the state-of-the-art ECHO-g model has been used to simulate underground temperature perturbation profiles. An inversion approach has been applied to reconstruct ground surface temperature histories from the simulated profiles and to compare them with the climate model temperatures. Results support the skill of borehole inversion methods to retrieve long-term temperature trends, and the robustness of using the present-day borehole network for reconstructing SAT variations., Ministerio de Educación y Ciencia (MEC), España, Natural Sciences and Engineering Research Council of Canada (NSERC), Canadian Foundation for Climate and Atmospheric Sciences (CFCAS), Canadá, Atlantic Innovation Fund (AIF), Canadá, Depto. de Física de la Tierra y Astrofísica, Fac. de Ciencias Físicas, TRUE, pub

© Author(s) 2012. This work is distributed under the Creative Commons Attribution 3.0 License. This work was funded by the Spanish Ministry of the Environment (project SALVA-SINOVAS, Ref. 200800050083542) and the Spanish Ministry of Science and Technology (projects SPEQMORE-CGL2008-06558-C02-02/CLI and SPEQTRES-CGL2011-29672-C02-02). The authors also gratefully acknowledge funding from the Euro-Mediterranean Institute of Water (IEA). J. J. Gómez Navarro thanks the Spanish Ministry of Education for his Doctoral scholarship (AP2006-04100). The work by E. Zorita is embedded in the EU-Project Millennium European Climate. Thanks to Elena Bustamante for the stimulating discussions., In this study we analyse the role of internal variability in regional climate simulations through a comparison of two regional paleoclimate simulations for the last millennium. They share the same external forcings and model configuration, differing only in the initial condition used to run the driving global model simulation. A comparison of these simulations allows us to study the role of internal variability in climate models at regional scales, and how it affects the long-term evolution of climate variables such as temperature and precipitation. The results indicate that, although temperature is homogeneously sensitive to the effect of external forcings, the evolution of precipitation is more strongly governed by random unpredictable internal dynamics. There are, however, some areas where the role of internal variability is lower than expected, allowing precipitation to respond to the external forcings. In this respect, we explore the underlying physical mechanisms responsible for it. This study identifies areas, depending on the season, in which a direct comparison between model simulations of precipitation and climate reconstructions would be meaningful, but also other areas where good agreement between them should not be expected even if both are perfect., Ministerio de Agricultura, Alimentación y Medio Ambiente (MAGRAMA), España, Ministerio de Ciencia y Tecnología (MCYT), España, Euro-Mediterranean Institute of Water (IEA), Ministerio de Educación, Cultura y Deporte (MECD), España, Millennium project: European climate of the last millennium, Unión Europea (UE), Depto. de Física de la Tierra y Astrofísica, Fac. de Ciencias Físicas, TRUE, pub

© 2000 American Meteorological Society. The authors thank the Hadley Centre for supplying the model data and two anonymous referees for their helpful comments. Funding was provided by the Comunidad de Madrid, Project CLI97- 0341-c0301, and the Ramón Areces Foundation., The lowest spatial scale at which current climate models are considered to be skillful is on the order of 1000 km because of resolution and computer capabilities. The estimation of the regional changes caused by anthropogenic emissions of greenhouse gases and aerosols therefore is problematic. Here a statistical downscaling scheme is used to study the relationship between large-scale sea lever pressure and regional precipitation in southwestern Europe, both in observed data and in outputs from a general circulation model (GCM) forced with increasing levers of greenhouse gases and sulfate aerosols. The results indicate that the GCM does reproduce the main aspects of the large- to local-scale coupled variability. Furthermore, these large- to local-scale relationships remain stable in the scenario simulations. The GCM runs predict increases of advection of oceanic air masses to the Iberian Peninsula that will produce a slight decrease of precipitation amounts in the north coast and the opposite effect in the rest of the territory, with values that could reach 10 mm decade^-1 in the south. In the homogenized historical records, the obtained pattern of change is very similar. These results support estimations of future regional trends simulated by the GCM under future emission scenarios., Comunidad de Madrid, Fundación Ramón Areces, Depto. de Física de la Tierra y Astrofísica, Fac. de Ciencias Físicas, TRUE, pub

Copyright 2007 by the American Geophysical Union. This study was financially supported by projects REN2002-04584-C04-01-CLI, REN-2002-04584-C04-04-CLI, CGL2005-06966-C07-04/CLI and CGL2005-06966-C07-05/CLI of the Spanish Ministry of Science and Technology. Jesús Fernández received support from the Department of Education, Universities and Research of the Basque Autonomous Government through grant BFI04.52. J. Sáenz received support by the research groups’ support program, project 9/UPV 00060.310-15343/2003, University of the Basque Country. The gridded precipitation and temperature data were supplied by the Climate Impacts LINK Project (UK Department of the Environment Contract EPG 1/1/16) on behalf of the Climatic Research Unit, University of East Anglia. The boundary conditions were downloaded from the NCEP/NCAR Web server. The National Institutes of Meteorology of Spain and Portugal provided access to daily records of temperature and precipitation at several sites. Other surface and boundary data were provided by the MARS system of the ECMWF. The authors thank the Pennsylvania State University/National Center for Atmospheric Research numerical model home page for making the MM5 model publicly available. Authors made extensive use of the Generic Mapping Tools software [Wessel and Smith, 1991]. GTOPO30 topography data are distributed by the Land Processes Distributed Active Archive Center (LP DAAC), located at the U.S. Geological Survey’s EROS Data Center http://LPDAAC.usgs.gov. We appreciate the comments on the manuscript made by Jimy Dudhia. The comments by three anonymous reviewers have also improved the final version of this manuscript., We present an analysis of the sensitivity to different physical parameterizations of a high-resolution simulation of the MM5 mesoscale model over the Iberian Peninsula. Several (16) 5-year runs of the MM5 model with varying parameterizations of microphysics, cumulus, planetary boundary layer and longwave radiation have been carried out. The results have been extensively compared with observational precipitation and surface temperature data. The parameterization uncertainty has also been compared with that related to the boundary conditions and the varying observational data sets. The annual cycles of precipitation and surface temperature are well reproduced. The summer season presents the largest deviations, with a 5 K cold bias in the southeast and noticeable precipitation errors over mountain areas. The cold bias seems to be related to the surface, probably because of the excessive moisture availability of the five-layer soil scheme used. No parameterization combination was found to perform best in simulating both precipitation and surface temperature in every season and subregion. The Kain-Fritsch cumulus scheme was found to produce unrealistically high summer precipitation. The longwave radiation parameterizations tested were found to have little impact on our target variables. Other factors, such as the choice of boundary conditions, have an impact on the results as large as the selection of parameterizations. The range of variability in the MM5 physics ensemble is of the same order of magnitude as the observational uncertainty, except in summer, when it is larger and probably related to the inaccuracy of the model to reproduce the summer precipitation over the area., Mininsterio de Ciencia y Tecnolgía (MCYT), España, Departamento de Educación, Política Lingüística y Cultura (Gobierno Vasco), Universidad del País Vasco / Euskal Herriko Unibertsitatea (UPV / EHU), Depto. de Física de la Tierra y Astrofísica, Fac. de Ciencias Físicas, TRUE, pub

© Author(s) 2009. This work is distributed under the Creative Commons Attribution 3.0 License. This research was supported: in Spain by project SPECT (CGL2005-06097/CLI) and the Ramón y Cajal Program of the Ministerio de Educación y Ciencia (MEC) and project PalMA (CCG07-UCM/ESP-3045) by the Comunidad Autónoma de Madrid and the Universidad Complutense de Madrid; in Canada by the Natural Sciences and Engineering Research Council of Canada (NSERC), the Canadian Foundation for Climate and Atmospheric Sciences (CFCAS) and the Atlantic Innovation Fund (AIF-ACOACanada); and in Germany by the EU project Millennium European Climate. The authors thank Vladimir Cermak and two anonymous reviewers for their comments and suggestions. Also we appreciate the contributions from Volker Rath and Jason Smerdon, editors of this special volume., Progress in understanding climate variability through the last millennium leans on simulation and reconstruction efforts. Exercises blending both approaches present a great potential for answering questions relevant both for the simulation and reconstruction of past climate, and depend on the specific peculiarities of proxies and methods involved in climate reconstructions, as well as on the realism and limitations of model simulations. This paper explores research specifically related to paleoclimate modeling and borehole climatology as a branch of climate reconstruction that has contributed significantly to our knowledge of the low frequency climate evolution during the last five centuries. The text flows around three main issues that group most of the interaction between model and geothermal efforts: the use of models as a validation tool for borehole climate reconstructions; comparison of geothermal information and model simulations as a means of either model validation or inference about past climate; and implications of the degree of realism on simulating subsurface climate on estimations of future climate change. The use of multi-centennial simulations as a surrogate reality for past climate suggests that within the simplified reality of climate models, methods and assumptions in borehole reconstructions deliver a consistent picture of past climate evolution at long time scales. Comparison of model simulations and borehole profiles indicate that borehole temperatures are responding to past external forcing and that more realism in the development of the soil model components in climate models is desirable. Such an improved degree of realism is important for the simulation of subsurface climate and air-ground interaction; results indicate it could also be crucial for simulating the adequate energy balance within climate change scenario experiments., SPECT, Programa Ramón y Cajal (Ministerio de Educación y Ciencia, MEC), Comunidad de Madrid, Universidad Complutense de Madrid (UCM), Natural Sciences and Engineering Research Council of Canada (NSERC), Canadian Foundation for Climate and Atmospheric Sciences (CFCAS), Atlantic Innovation Fund (AIF-ACOACanada), Unión Europea (UE), Proyecto PalMA, Project Millennium European Climate (UE), Depto. de Física de la Tierra y Astrofísica, Fac. de Ciencias Físicas, TRUE, pub

Copyright 2005 by the American Geophysical Union. We thank the two reviewers and Drs. D. Bray, J. Luterbacher, M. Montoya and E. Xoplaki for their comments and proof reading of this manuscript. This work was partially funded by the DEKLIM Program of the German BMBF, the EU project SO&P and by the project REN-2000-0786Cli of the Spanish CICYT., The spatial patterns of surface air-temperature variations in the period 1000 to 2100, simulated with the ECHO-G atmosphere-ocean coupled model, are analyzed. The model was driven by solar, volcanic and greenhouse gas forcing. The leading mode of temperature variability in the preindustrial period represents an almost global coherent variation of temperatures, with larger amplitudes over the continents and Northern Hemisphere. This mode also describes a large part of the spatial structure of the warming simulated in the 21st century. However, in the 21st century, regional departures from this spatial structure are also present and can be ascribed to atmospheric circulation responses to anthropogenic forcing in the last decades of the 21st century., DEKLIM Program (BMBF), Alemania, Unión Europea (UE), Comisión Interministerial de Ciencia y Tecnología (CICYT), España, Startseite des Webauftritts des Bundesministeriums für Bildung und Forschung (BMBF), Alemania, Depto. de Física de la Tierra y Astrofísica, Fac. de Ciencias Físicas, TRUE, pub

© Author(s) 2013. LFD was funded by a FPU grant: AP2009-4061. LFD and JFGR acknowledge project grants UCM-921407, CGL2008-06558-C02-02/CLI, CGL2011-29672-C02-02, 200800050083542 and 200800050084028. CCR acknowledges SNF-FUPSOL. DB acknowledges projects CGL2008-05968-C02-01 and ENAC-PTDC/AAC-CLI/103567/2008. JL acknowledges EU/FP7-ACQWA-NO212250, DFG-PRIME1,2, LU1608/1-1/AOBJ:568460 and LU1608/2-1/AOBJ:575150. JS, DS and PY acknowledge the ANR ESCARSEL grant., Understanding natural climate variability and its driving factors is crucial to assessing future climate change. Therefore, comparing proxy-based climate reconstructions with forcing factors as well as comparing these with paleo-climate model simulations is key to gaining insights into the relative roles of internal versus forced variability. A review of the state of modelling of the climate of the last millennium prior to the CMIP5-PMIP3 (Coupled Model Intercomparison Project Phase 5-Paleoclimate Modelling Intercomparison Project Phase 3) coordinated effort is presented and compared to the available temperature reconstructions. Simulations and reconstructions broadly agree on reproducing the major temperature changes and suggest an overall linear response to external forcing on multidecadal or longer timescales. Internal variability is found to have an important influence at hemispheric and global scales. The spatial distribution of simulated temperature changes during the transition from the Medieval Climate Anomaly to the Little Ice Age disagrees with that found in the reconstructions. Thus, either internal variability is a possible major player in shaping temperature changes through the millennium or the model simulations have problems realistically representing the response pattern to external forcing. A last millennium transient climate response (LMTCR) is defined to provide a quantitative framework for analysing the consistency between simulated and reconstructed climate. Beyond an overall agreement between simulated and reconstructed LMTCR ranges, this analysis is able to single out specific discrepancies between some reconstructions and the ensemble of simulations. The disagreement is found in the cases where the reconstructions show reduced covariability with external forcings or when they present high rates of temperature change., FPU, SNF-FUPSOL, ANR ESCARSEL, Depto. de Física de la Tierra y Astrofísica, Fac. de Ciencias Físicas, TRUE, pub

Copyright 2011 by the American Geophysical Union. Supported in part by NSF grants ATM0902436 and ATM0902715, by NASA grant NNX09AF44G, by NOAA grants NA07OAR4310060 and NA10OAR4320137, and by the European Project Millennium. Supplementary materials can be accessed at http://www.ldeo.columbia.edu/similar to jsmerdon/2011_grl_supplement.html. LDEO contribution 7471., The spatial skill of four climate field reconstruction (CFR) methods is investigated using pseudoproxy experiments (PPEs) based on two millennial-length general circulation model simulations. Results indicate that presently available global and hemispheric CFRs for the Common Era likely suffer from spatial uncertainties not previously characterized. No individual method produced CFRs with universally superior spatial error statistics, making it difficult to advocate for one method over another. Northern Hemisphere means are shown to be insufficient for evaluating spatial skill, indicating that the spatial performance of future CFRs should be rigorously tested for dependence on proxy type and location, target data and employed methodologies. Observed model-dependent methodological performance also indicates that CFR methods must be tested across multiple models and conclusions from PPEs should be carefully evaluated against the spatial statistics of real-world climatic fields. Citation: Smerdon, J. E., A. Kaplan, E. Zorita, J. F. Gonzalez-Rouco, and M. N. Evans (2011), Spatial performance of four climate field reconstruction methods targeting the Common Era, Geophys. Res. Lett., 38, L11705, doi: 10.1029/2011GL047372., National Science Foundation (NSF), National Aeronautics and Space Administration (NASA), National Oceanic and Atmospheric Administration (NOAA), EE.UU., European Project Millennium, Depto. de Física de la Tierra y Astrofísica, Fac. de Ciencias Físicas, TRUE, pub

© Author(s) 2011. This work is distributed under the Creative Commons Attribution 3.0 License. This work was funded by the Spanish Ministry of the Environment (project SALVA-SINOVAS, Ref. 200800050083542) and the Spanish Ministry of Science and Technology (project SPECMORE-CGL2008-06558-C02-02/CLI). The authors also gratefully acknowledge the funding from the Euro-Mediterranean Institute of Water (IEA). We acknowledge the E-OBS data set from the EU-FP6 project ENSEMBLES (http://ensembles-eu.metoffice.com) and the data providers in the ECA&D project (http://eca.knmi.nl). J. J. Gómez Navarro thanks the Spanish Ministry of Education for his Doctoral scholarship (AP2006-04100). We also thank Jürg Luterbacher for the interesting insights about uncertainties in proxy reconstructions, which improved the final version of this paper., A high-resolution (30 km) regional paleoclimate simulation of the last millennium over the Iberian Peninsula (IP) is presented. The simulation was performed with a climate version of the mesoscale model MM5 driven by the global model ECHO-G. Both models were driven by the same reconstructions of several external forcing factors. The high spatial resolution of the regional model allows climatologists to realistically simulate many aspects of the climate in the IP, as compared to an observational data set in the reference period 1961-1990. Although the spatial-averaged values developed by the regional model are tightly driven by the boundary conditions, it is capable to develop a different realisation of the past climate at regional scales, especially in the high-frequency domain and for precipitation. This has to be considered when comparing the results of climate simulations versus proxy reconstructions. A preliminary comparison of the simulation results with reconstructions of temperature and precipitation over the IP shows good agreement in the warming trends in the last century of the simulation, although there are large disagreements in key periods such as the precipitation anomalies in the Maunder Minimum., Ministerio de Medio Ambiente (MMA), Ministerio de Ciencia y Tecnología (MCYT), Euro-Mediterranean Institute of Water (IEA), Ministerio de Educación, Cultura y Deporte (MECD), ENSEMBLES-EU, Unión Europea. FP6, Depto. de Física de la Tierra y Astrofísica, Fac. de Ciencias Físicas, TRUE, pub

Coastal environments, in particular heavily populated semi-enclosed marginal seas and coasts like the Baltic Sea region, are strongly affected by human activities. A multitude of human impacts, including climate change, affect the different compartments of the environment, and these effects interact with each other. As part of the Baltic Earth Assessment Reports (BEAR), we present an inventory and discussion of different human-induced factors and processes affecting the environment of the Baltic Sea region, and their interrelations. Some are naturally occurring and modified by human activities (i.e. climate change, coastal processes, hypoxia, acidification, submarine groundwater discharges, marine ecosystems, non-indigenous species, land use and land cover), some are completely human-induced (i.e. agriculture, aquaculture, fisheries, river regulations, offshore wind farms, shipping, chemical contamination, dumped warfare agents, marine litter and microplastics, tourism, and coastal management), and they are all interrelated to different degrees. We present a general description and analysis of the state of knowledge on these interrelations. Our main insight is that climate change has an overarching, integrating impact on all of the other factors and can be interpreted as a background effect, which has different implications for the other factors. Impacts on the environment and the human sphere can be roughly allocated to anthropogenic drivers such as food production, energy production, transport, industry and economy. The findings from this inventory of available information and analysis of the different factors and their interactions in the Baltic Sea region can largely be transferred to other comparable marginal and coastal seas in the world.

Based on the Baltic Earth Assessment Reports of this thematic issue in Earth System Dynamics and recent peer-reviewed literature, current knowledge of the effects of global warming on past and future changes in climate of the Baltic Sea region is summarised and assessed. The study is an update of the Second Assessment of Climate Change (BACC II) published in 2015 and focuses on the atmosphere, land, cryosphere, ocean, sediments, and the terrestrial and marine biosphere. Based on the summaries of the recent knowledge gained in palaeo-, historical, and future regional climate research, we find that the main conclusions from earlier assessments still remain valid. However, new long-term, homogenous observational records, for example, for Scandinavian glacier inventories, sea-level-driven saltwater inflows, so-called Major Baltic Inflows, and phytoplankton species distribution, and new scenario simulations with improved models, for example, for glaciers, lake ice, and marine food web, have become available. In many cases, uncertainties can now be better estimated than before because more models were included in the ensembles, especially for the Baltic Sea. With the help of coupled models, feedbacks between several components of the Earth system have been studied, and multiple driver studies were performed, e.g. projections of the food web that include fisheries, eutrophication, and climate change. New datasets and projections have led to a revised understanding of changes in some variables such as salinity. Furthermore, it has become evident that natural variability, in particular for the ocean on multidecadal timescales, is greater than previously estimated, challenging our ability to detect observed and projected changes in climate. In this context, the first palaeoclimate simulations regionalised for the Baltic Sea region are instructive. Hence, estimated uncertainties for the projections of many variables increased. In addition to the well-known influence of the Nor

Until now, proxy records have been the primary tool for quantitative reconstructions of the physical world of the ancient and late antique Mediterranean. This chapter demonstrates the combined use of proxy datasets and the hitherto underutilized potential of earth system models in the scientific and historical study of past environmental variations and impacts on human societies. Results from model simulations are able to explain hydroclimatic anomalies observed in the proxy records and provide links to relevant mechanisms. The Late Roman Dry Period and the Late Roman Wet Period of the mid-fourth to early eighth centuries AD are each associated with the increase in the frequency of subsistence crises and with the accelerated infrastructural adaptations of communities and agricultural expansion, respectively. The chapter concludes with an examination of the historical and climatic contexts behind one such anomaly, a subsistence crisis in Cappadocia in the late 300s AD.

HIV-1 recurrently targets active genes and integrates in the proximity of the nuclear pore compartment in CD4+ T cells. However, the genomic features of these genes and the relevance of their transcriptional activity for HIV-1 integration have so far remained unclear. Here we show that recurrently targeted genes are proximal to super-enhancer genomic elements and that they cluster in specific spatial compartments of the T cell nucleus. We further show that these gene clusters acquire their location during the activation of T cells. The clustering of these genes along with their transcriptional activity are the major determinants of HIV-1 integration in T cells. Our results provide evidence of the relevance of the spatial compartmentalization of the genome for HIV-1 integration, thus further strengthening the role of nuclear architecture in viral infection.

Spatial covariance in the simulated temperature evolution over the past millennium has been reported to exceed that of multiproxy-based reconstructions. Here we use tree ring-based temperature reconstructions and state-of-the-art climate model simulations to assess temporal changes in Northern Hemisphere intercontinental temperature covariance during the last 1000 years. Tree ring-only approaches reveal stronger agreement with model simulations compared to multiproxy networks. Although simulated temperatures exhibit a substantial spread among individual models, intercontinental temperature coherency is mainly driven by the cooling of large volcanic eruptions in 1257, 1452, 1600, and 1815 Common Era. The coherence of these synchronizing events appears to be elevated in several climate simulations relative to their own unforced covariance baselines and in comparison to the proxy reconstructions. This suggests that some models likely overestimate the amplitude of abrupt summer cooling in response to volcanic eruptions, particularly at larger spatial scales.

The pre-industrial millennium is among the periods selected by the Paleoclimate Model Intercomparison Project (PMIP) for experiments contributing to the sixth phase of the Coupled Model Intercomparison Project (CMIP6) and the fourth phase of the PMIP (PMIP4). The past1000 transient simulations serve to investigate the response to (mainly) natural forcing under background conditions not too different from today, and to discriminate between forced and internally generated variability on interannual to centennial timescales. This paper describes the motivation and the experimental set-ups for the PMIP4-CMIP6 past1000 simulations, and discusses the forcing agents orbital, solar, volcanic, and land use/land cover changes, and variations in greenhouse gas concentrations. The past1000 simulations covering the pre-industrial millennium from 850 Common Era (CE) to 1849 CE have to be complemented by historical simulations (1850 to 2014 CE) following the CMIP6 protocol. The external forcings for the past1000 experiments have been adapted to provide a seamless transition across these time periods. Protocols for the past1000 simulations have been divided into three tiers. A default forcing data set has been defined for the Tier 1 (the CMIP6 past1000) experiment. However, the PMIP community has maintained the flexibility to conduct coordinated sensitivity experiments to explore uncertainty in forcing reconstructions as well as parameter uncertainty in dedicated Tier 2 simulations. Additional experiments (Tier 3) are defined to foster collaborative model experiments focusing on the early instrumental period and to extend the temporal range and the scope of the simulations. This paper outlines current and future research foci and common analyses for collaborative work between the PMIP and the observational communities (reconstructions, instrumental data).