RESEARCH PAPER The HYDE 3.1 spatially explicit database of human-induced global land-use change over the past 12,000 years Kees Klein Goldewijk*, Arthur Beusen, Gerard van Drecht and Martine de Vos Netherlands Environmental Assessment Agency, Bilthoven, The Netherlands ABSTRACT Aim This paper presents a tool for long-term global change studies; it is an update of the History Database of the Global Environment (HYDE) with estimates of some of the underlying demographic and agricultural driving factors. Methods Historical population, cropland and pasture statistics are combined with satellite information and specific allocation algorithms (which change over time) to create spatially explicit maps, which are fully consistent on a 5′ longitude/ latitude grid resolution, and cover the period 10,000 bc to ad 2000. Results Cropland occupied roughly less than 1% of the global ice-free land area for a long time until ad 1000, similar to the area used for pasture. In the centuries that followed, the share of global cropland increased to 2% in ad 1700 (c. 3 million km 2 ) and 11% in ad 2000 (15 million km 2 ), while the share of pasture area grew from 2% in ad 1700 to 24% in ad 2000 (34 million km 2 ) These profound land-use changes have had, and will continue to have, quite considerable consequences for global biogeochemical cycles, and subsequently global climate change. Main conclusions Some researchers suggest that humans have shifted from living in the Holocene (emergence of agriculture) into the Anthropocene (humans capable of changing the Earth’s atmosphere) since the start of the Industrial Revo- lution. But in the light of the sheer size and magnitude of some historical land-use changes (e.g. as result of the depopulation of Europe due to the Black Death in the 14th century and the aftermath of the colonization of the Americas in the 16th century) we believe that this point might have occurred earlier in time. While there are still many uncertainties and gaps in our knowledge about the importance of land use (change) in the global biogeochemical cycle, we hope that this database can help global (climate) change modellers to close parts of this gap. Keywords Agricultural development, cropland, DGVM, EMIC, ESM, historical population, human impact, IPCC, land use, pasture. *Correspondence: Kees Klein Goldewijk, Netherlands Environmental Assessment Agency, PO Box 303, 3720 AH Bilthoven, The Netherlands. E-mail: kees.kleingoldewijk@pbl.nl INTRODUCTION Imagine the evolution of the Earth taking place in 1 day: humankind has only been present on this planet since a few minutes to midnight, yet still we managed to obtain dominance over the world in that short time. Already more than 30% of the world’s landscape is under some sort of development (agricul- ture), another 30% is more or less influenced and many natural resources are heavily used or even depleted (Foley et al., 2005). All these activities have led to anthropogenic emissions of green- house gases and have subsequently influenced global (climate) change, but it is uncertain from which point in time, and to what extent, these influences have occurred. A key question is: how did this come so far? As long as humans have been present on Earth they have been altering the global landscape. These historical changes in land use, primarily conversion (deforestation) of undisturbed ecosys- tems to other forms of land use (cropland, grazing land), have contributed considerably to the cumulative increase in carbon dioxide (CO 2) in the atmosphere. Although estimates of Global Ecology and Biogeography, (Global Ecol. Biogeogr.) (2010) © 2010 Blackwell Publishing Ltd DOI: 10.1111/j.1466-8238.2010.00587.x www.blackwellpublishing.com/geb 1