History Database of the Global Environment - HYDE

The first version of this data base originally was set up for testing and
validation of the so-called Integrated Model of the Greenhouse Effect (the
IMAGE model; see Alcamo, 1994), developed at RIVM. The main aim of the model is
to use state-of-the-art models to assist policy makers in the development and
evaluation of future scenarios to mitigate the negative effects of global
change. The modelling framework consists of several subsystems that cover the
different aspects of the earth system.

Many calculations in IMAGE and other models are performed on a 0.5o by 0.5o
longitude/latitude grid. This is because nearly all potential impacts of
climate change (impacts on ecosystems, agriculture and coastal flooding) have a
strong spatial variability. Moreover, land use related greenhouse gas emissions
depend on local environmental conditions and human activity. There are also
other reasons for using grid-scale information. First, policy makers are
interested in regional/national policies to address climate change. Secondly,
grid-scale information makes model caluclations more testable against
observations as compared to more aggregated models.

Nevertheless, it is infeasable to perform grid-based calculations for economic
models, because of the difficulty in specifying economic/demographic factors on
a country scale for the entire world over the long horizon of the model.
Therefore, the world has been divided into 19 world regions, according to
economic and geographic similarity. This classification also takes into account
the regional aggregations used by the IPCC, OECD, FAO, UN and IEA. It should be
noted, however, that IMAGE has the additional requirement that countries within
a region be adjacent or nearby because of the model's approach to global land
cover simulation.

An important initiative for the update the previous version of HYDE (Klein
Goldewijk, 2001) was the publication of a new population density data base, the
Gridded World Population v.3 (Balk et al, 2005), which is now used as a
starting point for historical gridded population calculations. Because
population data are important in many calculations, it resulted in modified
land cover estimates, as well as estimates for GDP, value added, private
consumption. Furthermore, numerous new data have been incorporated in many
tables.

Besides the testing of IMAGE, HYDE has already been used for integrated
environmental assessents such as the Global Environmental Outlook (GEO) of the
United Nations Enviromental Programme (UNEP, 1997), technical background
reports for GEO (RIVM/UNEP, 1997), the TARGETS project (Rotmans and De Vries,
1997), the Dutch National Environmental Outlook (RIVM, 1997) and the Mappae
Mundi project (Goudsblom and De Vries, 2002). Also, HYDE has contributed to
other research e.g. in the field of historical atmospheric trace gas
inventories (e.g. Kroeze et al, 1999; den Elzen et al, 1999; van Aardenne et
al, 2001; Pitman et al, 2000; Pielke et al, 2003 ), biological diversity (e.g.
Gaston et al, 2003), and climate reconstructions (e.g. Matthews et al, 2003;
Brovkin et al, 2004).

Furthermore, this effort very much fits within the Land-Use and Land-Cover
Change LUCC project, (activity 3; database development), part of the the
International Human Dimensions Project (IHDP), and the PAGES (Human
Interactions in Past Environmental Changes) - focus 3: Human Impacts on
Terrestrial Ecosystems (HITE) initiative. PAGES is the International
Geosphere-Biosphere Programme (IGBP) core project charged with providing a
quantitative understanding of the Earth's past climate and environment.

Please note that this data base is far from complete. Work is continuous in
progress to update and extent the data series where possible.

[Summary provided by MNP]