Modelling for species and habitats: new opportunities for problem solving

The biodiversity convention aims at conserving biodiversity and guaranteeing fair and sustainable human use of biodiversity. The convention further requires that the causes of biodiversity decline are identified and evaluated, and that effective conservation and monitoring strategies are developed. Resolving these needs requires a different approach than those described in the last Global Biodiversity Assessment. This assessment tended to be descriptive and did not comprehensively attempt to describe future trends in biodiversity in relation to the major threats: habitat destruction, overexploitation, alien species, pollution and climate change. Integrated assessment modelling and scenario development have therefore not been introduced and applied to assess changes in biodiversity. These tools were originally developed for acidification and climate-change impact assessments but are also well suited to analysing other environmental problems. The implemented business-as-usual scenarios show the causes of biodiversity decline to differ regionally. Although complex patterns of causal factors and changes occur in many regions, a valid (but generalised) statement is that climate change causes biodiversity decline in industrialised regions, while in developing regions expanding land use is the major contributor. The scenarios further highlight that despite population growth contributing to the problem, rapidly increasing consumption patterns, rapid expansion of rangelands to support changing diets and too slow-moving technological innovations are major attributes of land-use change and biodiversity decline. Finally, it is concluded that scenario studies transparently highlight the complex systemic interactions and feedback between society and the other components of the earth's system. In addition, scenarios can contribute well to improving the understanding of changes in biodiversity at global and regional levels of assessment. (C) 1999 Elsevier Science B.V. All rights reserved.