Modelling for species and habitats: new opportunities for problem solving

The biodiversity convention aims at conserving biodiversity and guaranteein g fair and sustainable human use of biodiversity. The convention further re quires 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 desc riptive and did not comprehensively attempt to describe future trends in bi odiversity in relation to the major threats: habitat destruction, overexplo itation, 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 environmenta l problems. The implemented business-as-usual scenarios show the causes of biodiversity decline to differ regionally. Although complex patterns of cau sal factors and changes occur in many regions, a valid (but generalised) st atement is that climate change causes biodiversity decline in industrialise d regions, while in developing regions expanding land use is the major cont ributor. The scenarios further highlight that despite population growth con tributing to the problem, rapidly increasing consumption patterns, rapid ex pansion of rangelands to support changing diets and too slow-moving technol ogical innovations are major attributes of land-use change and biodiversity decline. Finally, it is concluded that scenario studies transparently high light the complex systemic interactions and feedback between society and th e other components of the earth's system. In addition, scenarios can contri bute well to improving the understanding of changes in biodiversity at glob al and regional levels of assessment. (C) 1999 Elsevier Science B.V. All ri ghts reserved.