Climate of the Past Discussions www.clim-past-discuss.net 1814-9340 1814-9359 6 2 2010 10.5194/cpd-6-307-2010 http://www.clim-past-discuss.net/6/307/2010/ http://www.clim-past-discuss.net/6/307/2010/cpd-6-307-2010.html http://www.clim-past-discuss.net/6/307/2010/cpd-6-307-2010.pdf 307 346 2010-03-11 Holocene land-cover reconstructions for studies on land cover-climate feedbacks M.-J. Gaillard marie-jose.gaillard-lemdahl@lnu.se S. Sugita F. Mazier J. O. Kaplan A.-K. Trondman A. Broström T. Hickler E. Kjellström P. KuneÅ¡ C. Lemmen J. Olofsson B. Smith G. Strandberg School of Pure and Applied Sciences, Linnaeus University, 39182 Kalmar, Sweden Institute of Ecology, Tallinn University, 10120 Tallinn, Estonia GEODE, UMR 5602, University of Toulouse, 5 allée A. Machado, 31058 Toulouse Cedex, France ARVE Group, Ecole Polytechnique Fédérale de Lausanne, Station 2, 1015 Lausanne, Switzerland Department of Earth and Ecosystem Sciences, Lund University, Sölvegatan 12, 223 62 Lund, Sweden Swedish Meteorological and Hydrological Institute, 60176 Norrköping, Sweden Institute of Earth Sciences, Aarhus University, C. F. Møllers Allé 4, 8000 Ã…rhus C, Denmark Institute for Coastal Research, GKSS-Forschungszentrum Geesthacht GmbH, 21502 Geesthacht, Germany The major objectives of this paper are: (1) to review the pros and cons of the scenarios of past anthropogenic land cover change (ALCC) developed during the last ten years, (2) to discuss issues related to pollen-based reconstruction of the past land-cover and introduce a new method, REVEALS (Regional Estimates of VEgetation Abundance from Large Sites), to infer long-term records of past land-cover from pollen data, (3) to present a new project (LANDCLIM: LAND cover – CLIMate interactions in NW Europe during the Holocene) currently underway, and show preliminary results of REVEALS reconstructions of the regional land-cover in the Czech Republic for five selected time windows of the Holocene, and (4) to discuss the implications and future directions in climate and vegetation/land-cover modeling, and in the assessment of the effects of human-induced changes in land-cover on the regional climate through altered feedbacks. The existing ALCC scenarios show large discrepancies between them, and few cover time periods older than AD 800. When these scenarios are used to assess the impact of human land-use on climate, contrasting results are obtained. It emphasizes the need of REVEALS model-based land-cover reconstructions. They might help to fine-tune descriptions of past land-cover and lead to a better understanding of how long-term changes in ALCC might have influenced climate. The REVEALS model is proved to provide better estimates of the regional vegetation/land-cover changes than the traditional use of pollen percentages. Thus, the application of REVEALS opens up the possibility of achieving a more robust assessment of land cover at regional- to continental-spatial scale throughout the Holocene. We present maps of REVEALS estimates for the percentage cover of 10 plant functional types (PFTs) at 200 BP and 6000 BP, and of the two open-land PFTs "grassland" and "agricultural land" at five time-windows from 6000 BP to recent time. The LANDCLIM results are expected to provide crucial data to reassess ALCC estimates for a better understanding of the land suface-atmosphere interactions. Andersen, S. T.: The Relative Pollen Productivity and Pollen Representation of North European Trees, and Correction Factors for Tree Pollen Spectra, Determined by Surface Pollen Analyses from Forests, Geological Survey of Denmark, II Series, 96,~C A. Reitzels, Copenhagen, 96~pp., 1970. Anderson, J., Bugmann, H., Dearing, J. A., and Gaillard, M.-J.: Linking palaeoenvironmental data and models to understand the past and to predict the future, Trends. Ecol. Evol., 21(12), 696–704, 2006. Bala, G., Caldeira, K., Wickett, M., Phillips, T. J., Lobell, D. B., Delire, C., and Mirin, A.: Combined climate and carbon-cycle effects of large-scale deforestation, in: Proceedings of the National Academy of Sciences, USA, 104, 6550–6555, 2007. Betts, R.: Offset of the potential carbon sink from boreal forestation by decreases in surface albedo, Nature, 408, 187–190, 2000. Björse, G., Bradshaw, R. H. W., and Michelson, D. B.: Calibration of regional pollen data to construct maps of former forest types in southern Sweden, J. Paleolimnol., 16, 67–78, 1996. Beug, H. J.: Leitfaden der Pollenbestimmung für Mitteleuropa und angrenzande Gebiete, Verlag Dr. Friedrich Pfeil, München, 2004. Bradshaw, R. H. W.: Modern pollen representation factors for woods in South-West England, J. Ecol., 69, 45–70, 1981. Broström, A., Sugita, S., and Gaillard, M.-J.: Pollen productivity estimates for the reconstruction of past vegetation cover in the cultural landscape of southern Sweden, Holocene, 14(3), 368–381, 2004. Broström, A., Nielsen, A. B., Gaillard, M.-J., Hjelle, K., Mazier, F., Binney, H., Bunting, J., Fyfe, R., Meltsov, V., Poska, A., Räsänen, S., Soepboer, W., von Stedingk, H., Suutari, H., and Sugita, S.: Pollen productivity estimates – the key to landscape reconstructions, Veg. Hist. Archaeobot., 17, 461–478, 2008. Brovkin, V., Claussen, M., Driesschaert, E., Fichefet, T., Kicklighter, D., Loutre, M. F., Matthews, H. D., Ramankutty, N., Schaeffer, M., and Sokolov, A.: Biogeophysical effects of historical land cover changes simulated by six Earth system models of intermediate complexity, Clim. Dynam., 26(6), 587–600, 2006. Campos, C. P., Muylaert, M. S., and Rosa, L. P.: Historical CO₂ emission and concentrations due to land use change of croplands and pastures by country, Sci. Total. Environ., 346, 149–155, 2003. Claussen, M., Brovkin, V., Calov, R., Ganopolski, A., and Kubatzki, C.: Did humankind prevent a holocene glaciation? Comment on Ruddiman's hypothesis of a pre-historic anthropocene, Climatic Change, 69, 409–417, 2005. Cox, P. M., Betts, R. A., Jones, C. D., Spall, S. A., and Totterdell, I. J.: Acceleration of global warming due to carbon-cycle feedbacks in a coupled climate model, Nature, 408, 184–187, 2000. Cox, P. M., Betts, R. A., Collins, M., Harris, P. P., Huntingford, C., and Jones, C. D.: Amazonian forest dieback under climate-carbon cycle projections for the 21st century, Theor. Appl. Climatol., 78, 137–156, 2004. Cramer, W., Bondeau, A., Woodward, F. I., Prentice, I. C., Betts, R. A., Brovkin, V., Cox, P. M., Fisher, V., Foley, J. A., Friend, A. D., Kucharik, C., Lomas, M. R., Ramankutty, N., Sitch, S., Smith, B., White, A., and Young-Molling, C.: Global response of terrestrial ecosystem structure and function to CO₂ and climate change: results from six dynamic global vegetation models, Glob. Change Biol., 7, 357–373, 2001. Dearing, J. A.: Climate-human-environment interactions: resolving our past, Clim. Past, 2, 187–203, 2006. Denman, K. L., Brasseur, G., Chidthaisong, A., Ciais, P., Cox, P. M., Dickinson, R. E., Hauglustaine, D., Heinze, C., Holland, E., Jacob, D., Lohmann, U., Ramachandran, S., da Silva Dias, P. L., Wofsy, S. C., and Zhang, X.: Couplings between changes in the climate system and biogeochemistry, in: Climate change 2007: The Physical Science Basis, Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC), edited by: Solomon, S., Qin, D., Manning, M., Chen, Z., Marquis, M., Averyt, K. B., Tignor, M., and Miller, H. L., Cambridge University Press, Cambridge, UK and New York, NY, USA, 499–587, 2007. DeFries, R. S., Field, C. B., Fung, I., Collatz, G. J., and Bounoua, L.: Combining satellite data and biogeochemical models to estimate global effects of human-induced land cover change on carbon emissions and primary productivity, Global. Biogeochem. Cy., 13, 803–815, 1999. Dekker, S. C., Rietkerk, M., and Bierkens, M. F. P.: Coupling microscale vegetation-soil water and macroscale vegetation-precipitation feedbacks in semiarid ecosystems, Global Change Biol. 13, 671–678, 2007. Duffin, K. and Bunting, M. J.: Relative pollen productivity and fall speed estimates for southern African savanna taxa, Veg. Hist. Archaeobot., 17, 507–525, 2008. Foley, J. A., Costa, M. H., Delire, C., Ramankutty, N., and Snyder, P.: Green surprise? How terrestrial ecosystems could affect earth's climate, Front. Ecol. Environ., 1, 38–44, 2003. Friedlingstein, P., Cox, P., Betts, R., Bopp, L., von Bloh, W., Brovkin, V., Cadule, P., Doney, S., Eby, M., Fung, I., Bala, G., John, J., Jones, C., Joos, F., Kato, T., Kawamiya, M., Knorr, W., Lindsay, K., Matthews, H. D., Raddatz, T., Rayner, P., Reick, C., Roeckner, E., Snitzler, K.-G., Schnur, R., Strassmann, K., Weaver, A. J., Yoshikawa, C., and Zeng, N.: Climate-carbon cycle feedback analysis: Results from the C4MIP model intercomparison, J. Clim., 19, 3337–3353, 2006. Fyfe, R. M., de Beaulieu, J.-L., Binney, H., Bradshaw, R. H. W., Brewer, S., Le Flao, A., Finsinger, W., Gaillard, M.-J., Giesecke, T., Gil-Romera, G., Grimm, E. C., Huntley, B., KuneÅ¡, P., Kühl, N., Leydet, M., Lotter, A. F., Tarasov, P. E., and Tonkov, S.: The European Pollen Database: past efforts and current activities, Veg. Hist. Archaeobot., 18(5), 417–424, 2009. Gaillard, M.-J.: Detecting Human impact in the pollen record, in: Encyclopedia of Quaternary Science, edited by: Elias, S. A., Elsevier, University of London, 2570–2595, 2007. Gaillard, M.-J., Dutoit, T., Hjelle, K., Koff, T., and O'Connell, M.: European cultural landscapes: insights into origins and development, in: Cultural Landscapes of Europe, edited by: Krzywinski, K., O'Connell, M., and Küster, H., Aschenbeck Media, Bremen, 35–46, 2009. Gaillard, M.-J., Sugita, S., Bunting, M. J., Dearing, J. A., and Bittmann, F.: Human impact on terrestrial ecosystems, pollen calibration and quantitative reconstruction of past land-cover, Veg. Hist. Archaeobot., 17, 415–418, 2008. Hellman, S., Bunting, M. J., and Gaillard, M.-J.: Relevant Source Area of Pollen in patchy cultural landscapes and signals of anthropogenic landscape disturbance in the pollen record: A simulation approach, Rev. Palaeobot. Palyno., 153, 245–258, 2009. Hellman, S., Gaillard, M.-J., Broström, A., and Sugita, S.: The REVEALS model, a new tool to estimate past regional plant abundance from pollen data in large lakes – validation in southern Sweden, J. Quaternary Sci., 23(1), 21–42, 2008a. Hellman, S., Gaillard, M.-J., Broström, A., and Sugita, S.: Effects of the sampling design and selection of parameter values on pollen-based quantitative reconstructions of regional vegetation: a case study in southern Sweden using the REVEALS model, Veg. Hist. Archaeobot., 17, 445–459, 2008b. Holmqvist, B. H. and Bradshaw, R. H. W.: Classification of large pollen data sets using unsupervised neural networks, Ecol. Model., in review, 2010. Houghton, R. A.: Revised estimates of the annual net flux of carbon to the atmosphere from changes in land use and land management 1850–2000, Tellus, 55B, 378–390, 2003. Jones, C. G., Ullerstig, A., Willén, U., and Hansson, U.: The Rossby Centre Regional Atmospheric Model (RCA): Part I: Model climatology and performance characteristics for the present climate over Europe, Ambio, 33(4–5), 199–210, 2004. Kaplan, J., Krumhardt, K., and Zimmermann, N.: The prehistoric and preindustrial deforestation of Europe, Quaternary Sci. Rev., 28, 3016–3034, 2009. Kjellström, E., Döscher, R., and Meier, H. E. M.: Atmospheric response to different sea surface temperatures in the Baltic Sea: Coupled versus uncoupled regional climate model experiments, Nord. Hydrol., 36(4–5), 397–409, 2005. Kjellström, E., Nikulin, G., Hansson, U., Strandberg, G., and Ullerstig, A.: 21st century changes in the European climate: uncertainties derived from an ensemble of regional climate model simulations, Tellus A, submitted, 2010a. Kjellström, E., Brandefelt, J., Näslund, J. O., Smith, B., Strandberg, G., Voelker, A. H. L., and Wohlfarth, B.: Simulated climate conditions in Fennoscandia during a MIS3 stadial, Boreas, in review, 2010b. Klein Goldewijk, K.: Estimating global land use change over the past 300 years: The HYDE Database, Global Biogeochem, Cy., 15, 417–433, 2001. Klein Goldewijk, K., Bouwman, A. F., and van Drecht, G.: Mapping contemporary global cropland and grassland distributions on a 5 by 5 minute resolution, Journal of Land Use Science, 2(3), 167–190, 2007. Klein Goldewijk, K., Beusen, A., and Janssen, P.: Long term dynamic modeling of global population and built-up area in a spatially explicit way, HYDE 3.1, The Holocene, in press, 2010. Krumhardt, K. M., Lemmen, C., and Kaplan, J. O. A.: Global dataset of human population and urbanization over the Holocene, in preparation, 2010. Krzywinski, K., O'Connell, M., and Küster, H. (Eds): Cultural Landscapes of Europe, Aschenbeck Media, Bremen, 218~pp., 2009. KuneÅ¡, P., Abraham, V., Kováøík, O., Kopeck\'y, M., and PALYCZ contributors: Czech Quaternary Palynological Database (PALYCZ): review and basic statistics of the data, Preslia, 8, 209–238, 2009. Kutzbach, J. E., Bartlein, P. J., Foley, J. A., Harrison, S. P., Hostetler, S. W., Liu, Z., Prentice, I. C., and Webb III, T.: Potential role of vegetation feedback in the climate sensitivity of high-latitude regions: a case study at 6000 Years~BP, Global Biogeochem. Cy., 10, 727–736, 1996. Lemmen, C.: World distribution of land cover changes during Pre- and Protohistoric Times and estimation of induced carbon releases, Géomorphologie, 2009(4), 303–312, 2009. Lewthwaite, J. W. and Sherratt, A.: Chronological Atlas, in: Cambridge Encyclopedia of Archeology, edited by: Sherratt, A., Cambridge University Press, Cambridge, 437–452, 1980. Lindbladh, M., Bradshaw, R., and Holmqvist, B. H.: Pattern and process in south Swedish forests during the last 3000-years sensed at stand and regional scales, J. Ecol., 88(1), 113–128, 2000. Meehl, G. A., Stocker, T. F., Collins, W., Friedlingstein, P., Gaye, A., Gregory, J., Kitoh, A., Knutti, R., Murphy, J., Noda., A., Raper, S., Watterson., I., Weaver, A., and Ci Zhao, Z.: Global Climate projections, in: Climate Change 2007: The Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, edited by: Solomon, S., Qin, D., Manning, M., Chen, Z., Marquis, M., Averyt, K. B., Tignor, M., and Miller, H. L., Cambridge University Press, Cambridge, UK and New York, NY, USA, 747–845, 2007. Mazier, F., KuneÅ¡, P., Sugita, S., Trondman, A.-K., Broström, A., and Gaillard, M.-J.: Pollen-inferred quantitative reconstructions of Holocene land-cover in NW Europe for the evaluation of past climate-vegetation feedbacks –Evaluation of the REVEALS-based reconstruction using the Czech Republic database, J. Quaternary Sci, in preparation, 2010. McEvedy, C. and Jones, R.: Atlas of world population history, Puffin Books, Harmondsworth, Middlesex, London, England, 368~pp., 1978. McGuire, A. D., Sitch, S., Clein, J. S., Dargaville, R., Esser, G., Foley, J., Heimann, M., Joos, F., Kaplan, J., Kicklighter, D. W., Meier, R. A., Melillo, J. M., Moore III, B., Prentice, I. C., Ramankutty, N., Reichenau, T., Schloss, A., Tian, H., Williams, L. J., and Wittenberg, U.: Carbon balance of the terrestrial biosphere in the twentieth century: Analysis of CO₂, climate and land use effects with four process-based ecosystem models, Global Biogeochem. Cy., 15, 183–206, 2001. Moberg, A., Jones, P. D., Lister, P., et al.: Indices for daily temperature and precipitation extremes in Europe analyzed for the period 1901–2000, J. Geophys. Res., 111, D22106, doi:10.1029/2006JD007103, 2006. Nevle, R. J. and Bird, D. K.: Effects of syn-pandemic fire reduction and reforestation in the tropical Americas on atmospheric CO₂ during European conquest, Palaeogeogr. Paleocl., 264, 25–38, 2008. Olofsson, J. and Hickler, T.: Effects of human land-use on the global carbon cycle during the last 6000~years, Veg. Hist. Archaeobot., 17(5), 605–615, 2008. Pongratz, J., Reick, C., Raddatz, T., and Claussen, M.: A reconstruction of global agricultural areas and land cover for the last millennium, Global Biogeochem. Cy., 22, GB3018, doi:10.1029/2007GB003153, 2008. Prentice, I. C.: Pollen representation, source area, and basin size: Toward a unified theory of pollen analysis, Quaternary Res., 23(1), 76–86, 1985. Prentice, I. C.: Records of vegetation in time and space: the principles of pollen analysis, in: Vegetation history, edited by: Huntley, B. and Webb, T., Kluwer Academic Publishers, Dordrecht, Netherlands, 17–42, 1988. Prentice, I. C., Jolly, D., and BIOME 6000 Participants: Mid-Holocene and glacial-maximum vegetation geography of the northern continents and Africa, J. Biogeogr., 27, 507–519, 2000. Prentice, I. C., Bondeau, A., Cramer, W., Harrison, S. P., Hickler, T., Lucht, W., Sitch, S., Smith, B., and Sykes, M. T.: Dynamic global vegetation modelling: quantifying terrestrial ecosystem responses to large-scale environmental change, in: Terrestrial Ecosystems in a Changing World, edited by: Canadell, J. G., Pataki, D. E., and Pitelka, L. F., Springer Verlag, Berlin, 175–192, 2007. Punt, W.: The Northwest European Pollen Flora I-VIII, Elsevier Scientific, Amsterdam, 1976–2003. Räisänen, J., Hansson, U., Ullerstig, A., Döscher, R., Graham, L. P., Jones, C., Meier, M., Samuelsson, P., and Willén, U.: GCM driven simulations of recent and future climate with the Rossby Centre coupled atmosphere – Baltic Sea regional climate model RCAO, Reports Meteorology and Climatology 101, Norrköping, Sweden, SMHI, 2003. Räisänen, J., Hansson, U., Ullerstieg, A., Döscher, R., Graham, L. P., Jones, C., Meier, H. E. M., Samuelsson, P., and Willén, U.: European climate in the late 21st century: regional simulations with two driving global models and two forcing scenaios, Clim. Dynam., 22, 13–31, 2004. Ramankutty, N. and Foley, J. A.: Estimating historical changes in global land cover: Croplands from 1700 to 1992, Glob. Biogeochem. Cy., 13, 997–1027, 1999. Ruddiman, W. F.: The Anthropogenic Greenhouse Era Began Thousands of Years Ago, Climatic Change, 61, 261–293, 2003. Ruddiman, W. F.: The early anthropogenic hypothesis a year later, Climatic Change, 69, 427–434, 2005. Rummukainen, M., Räisänen, J., Ullerstig, A., Bringfelt, B., Hansson, U., Graham, P., and Willén, U.: RCA – Rossby Centre regional Atmospheric climate model: model description and results from the first multi-year simulation, Reports Meteorology and Climatology No. 83, Swedish Meteorological and Hydrological Institute, Norrköping, Sweden, 76~pp., 1998. Rummukainen, M., Räisäinen, J., Bringfelt, B., Ullerstig, A., Omstedt, A., et al.: A regional climate model for northern Europe: model description and results from the downscaling of two GCM control simulations, Clim. Dyn., 17, 339–359, 2001. Samuelsson, P., Gollvik, S., Hansson, U., Jones, C., Kjellström, E., Nikulin, G., Ullerstig, A., Willén, U., and Wyser, K.: The Rossby Centre Regional Climate Model RCA3: Model description and performance, Tellus A, submitted, 2010. Sellers, P. J., Dickinson, R. E., Randall, D. A., Betts, A. K., Hall, F. G., Berry, J. A., Collatz, G. J., Denning, A. S., Mooney, H. A., Nobre, C. A., Sato, N., Field, C. B., and Henderson-Sellers, A.: Modeling the Exchange of Energy, Water, and Carbon between Continents and the Atmosphere, Science, 275, 502–509, 1997. Seppä, H., Alenius, T., Muukonen, P., Giesecke, T., Miller, P. A., and Ojala, A. E. K.: Calibrated pollen accumulation rates as a basis for quantitative tree biomass reconstructions, Holocene, 19, 209–220, 2009. Sitch, S., Smith, B., Prentice, I. C., Arneth, A., Bondeau, A., Cramer, W., Kaplan, J. O., Levis, S., Lucht, W., Sykes, M. T., Thonicke, K., and Venevsky, S.: Evaluation of ecosystem dynamics, plant geography and terrestrial carbon cycling in the LPJ dynamic global vegetation model, Glob. Change Biol. 9, 161–185, 2003. Smith, B., Prentice, I. C., and Sykes, M. T.: Representation of vegetation dynamics in modelling of terrestrial ecosystems: comparing two contrasting approaches within European climate space, Global Ecol. Biogeogr., 10, 621–637, 2001. Soepboer W., Sugita, S., and Lotter A.: Regional vegetation-cover changes on the Swiss Plateau during the past two millennia: A pollen-based reconstruction using the REVEALS model, Quaternary Sci. Rev., 29(3–4), 472–483, 2010. Strandberg, G., Brandefelt, J., Kjellström, E., and Smith, B.: High resolution regional simulation of Last Glacial Maximum climate in Europe, Tellus A, submitted, 2010. Sugita, S.: Pollen representation of vegetation in quaternary sediments: theory and method in patchy vegetation, J. Ecol., 82, 881–897, 1994. Sugita, S.: Theory of quantitative reconstruction of vegetation. I: Pollen from large lakes REVEALS regional vegetation composition, Holocene, 17(2), 229–241, 2007a. Sugita, S.: Theory of quantitative reconstruction of vegetation II: all you need is LOVE, Holocene, 17(2), 243–257, 2007b. Sugita, S., Gaillard, M.-J., and Broström, A.: Landscape openness and pollen records: a simulation approach, Holocene, 9, 409–421, 1999. Sugita, S., Gaillard, M.-J., Hellman, S., and Broström, A.: Model-based reconstruction of vegetation and landscape using fossil pollen, in: Layers of Perception, Kolloquien zur Vor- und Frühgeschichte Vol. 10, Bonn, Germany, 385–391, 2008. Sugita, S., Parshall, T., Calcote, R., and Walker, K.: Testing Landscape Reconstruction Algorithm for spatially-explicit reconstruction of vegetation in northern Michigan and Wisconsin, Quaternary Res., in review, 2010. Tarasov,, P., Williams, J. W., Andreev, A., Nakagawa, T.,Bezrukova, E., Herzschuh, U., Igarashi, Y., Müller, S.,Werner, K., and Zheng, Z.: Satellite- and pollen-based quantitative woody cover reconstructions for northern Asia: Verification and application to late Quaternary pollen data, Earth. Planet. Sc. Lett., 264(1–2), 284–298, 2007. Trondman A.-K., Gaillard, M.-J., Mazier, F., Sugita, S., Alenius, T., Bjune, A., Kangur, M., Latalowa, M., and Leydet, M.: Pollen-inferred quantitative reconstructions of Holocene land-cover in NW Europe for the evaluation of past climate-vegetation feedbacks – Protocol of the LANDCLIM project and the example of Sweden, Holocene, in preparation, 2010. van der Linden, P. and Mitchell, J. F. B. (Eds.): ENSEMBLES: Climate change and its impacts: Summary of research and results from the ENSEMBLES project, Met Office Hadley Centre, FitzRoy Road, Exeter EX1 3PB, UK, 160~pp., 2009. Vitousek, P. M., Mooney, H. A., Lubchenco, J., and Melillo, J. M.: Human domination of Earth's ecosystems, Science, 277, 494–499, 1997. Williams, J. W., Gonzales, L. M., and Kaplan, J. O.: Leaf area index for northern and eastern North America at the Last Glacial Maximum: a data-model comparison, Global Ecol. Biogeogr., 17, 122–134, 2008. Wirtz, K. and Lemmen, C.: A global dynamic model for the Neolithic transition, Climatic Change, 59(3), 333–367, 2003. Wirtz, K. W., Bernhardt, K., Lohmann, G., and Lemmen, C.: Mid-Holocene regional reorganization of climate variability, Clim. Past Discuss., 5, 287–326, 2009. Wolf, A., Callaghan, T. V., and Larson, K: Future changes in vegetation and ecosystem function of the Barents Region, Climatic Change, 87, 51–73, 2008. Wramneby, A., Smith, B., and Samuelsson, P.: Hotspots of vegetation-climate feedbacks under future greenhouse forcing in Europe, iLEAPS Newsletter 7, 26–27, 2009.