Historical Land Use Change Estimates for Climate Modelers: Results from The HYDE Database.

It is beyond doubt that human activities always have modified the natural environment, but it has become clear that during the last centuries the intensity and scale of these modifications has increased dramatically. Land cover changes affect climate by their impact on surface energy and moisture budgets, and thus should be included in global climate models. Therefore, a growing need is developed for better knowledge of historical land cover. A database with historical data of the global environment (HYDE) was created, which can be used in global climate models. HYDE covers not only land use (changes), but also general topics such as population, livestock, gross domestic product, and value added of industry and/or services as well. These driving forces occur at several spatial and temporal scales and dimensions, and differ often among regions. This requires a geographically explicit modeling approach. Where possible, data have been organized at the country level, and for the period 1700 to 1990. Some data are also available with geographic detail (Klein Goldewijk, 2001; Klein Goldewijk and Battjes, 1997). Examples of a global reconstruction of 300 years historical land use are presented, using gridded historical population estimates as a proxy for allocation of agricultural land. References: Klein Goldewijk, K., 2001. Estimating Global Land Use over the past 300 years: The HYDE 2.0 database. Global Biogeochemical Cycles 15(2): 417--433. Klein Goldewijk, C.G.M. and J.J. Battjes, 1997. A Hundred Year (1890 1990) Database for Integrated Environmental Assessments (HYDE, version 1.1). RIVM Report no. 422514002. National Institute of Public Health and Environmental Protection (RIVM). 196 pp. Internet: http://www.rivm.nl/env/int/hyde/