Integrated Assessment Modelling

In the middle of the 1990s, integrated assessment went through a period of introspection (Dowlatabadi, 1995; Grubb, 1993; Henderson-Sellers, 1996; Kolstad, 1998; Morgan and Dowlatabadi, 1996; Parson, 1995, 1996; Risbey et al., 1996; Rotmans and van Asselt, 1996; Rotmans, 1998; Rotmans and Dowlatabadi, 1998; Schneider, 1997; Shackley et al., 1998a,b; Thompson, 1997; Tol and Vellinga, 1998; Toth and Hizsnyik, 1998; Weyant et al., 1996). Around 1995, very different types of models had emerged – all under the label of integrated assessment modelling – and a new breed of integrated assessment – now known as participatory integrated assessment – challenged the models. The IA community was split into two, perhaps three or four camps: policy simulation modellers (Alcamo and Kreileman, 1996; Morita et al., 1994; Rotmans et al., 1990) were pitted against policy optimisation modellers (Carraro and Galeotti, 1996; Maddison, 1995; Manne et al., 1995; Nordhaus, 1994; Peck and Teisberg, 1992, Richels and Edmonds, 1995; Tol, 1997; Wigley et al., 1996), with a few uncertainty modellers claiming that both had it wrong (Dowlatabadi and Morgan, 1993; Plambeck et al., 1997; van Asselt et al., 1996; Yohe and Wallace, 1996), and those advocating participatory integrated assessment methods arguing for a much reduced role of models in policy advice, and for a drastic overhaul of the models as well (Bailey, 1997; Bailey et al., 1996; Cohen 1997; C. Jaeger, 1998; J. Jaeger, 1998; Munda, 1996; Parson, 1997). Fundamental questions were asked, such as what is integrated assessment, and what is it good for? The European Forum on Integrated Environmental Assessment was one of the results of this process of introspection, as integrated assessors realised that, however great the differences, they have more in common with each other than with disciplinary researchers.