Chapter 7
INTEGRATED ASSESSMENT MODELLING
J. Rotmans and M. van Asselt
7.1 Introduction
The increasing mutual interplay between social, economic, and
environmental issues demands integrated policies. Despite an early history
of isolated regulatory initiatives related to for instance air, water, and soil
over the past two decades, environmental policies have become increasingly
integrated. Nevertheless, this is only a first step towards further integration
of environmental, social and economic policies. The complexity of the
pressing issues, like global climate change, demands an integrated approach
to ensure that key interactions, feedbacks and effects are not inadvertently
omitted from the analysis. The various pieces of the complex puzzle can no
longer be examined in isolation. Integrated Assessment (IA) aims to fit the
pieces of the puzzle together, thereby indicating priorities for policy.
There is increasing recognition and credibility for the rapidly evolving
field of Integrated Assessment. Within the setting of the political arena, it is
accepted that IA can be supportive in the long-term policy planning process,
while in the scientific community more and more scientists do realise the
complementary value of IA research.
One of the problems of IA is still the many definitions and interpretations
that circulate (Weyant et al, 1996; Rotmans and Dowlatabadi, 1998; Parson,
1996; Ravetz, 1997; Jaeger et al., 1997). Notwithstanding this diversity,
these definitions have three elements in common, i.e. interdisciplinarity,
decision-support and participation of stakeholders. Thus irrespective of
whatever definition is taken, IA can be described as (Rotmans, 1998):

240 Chapter 7
a structured process of dealing with complex issues, using knowledge
from various scientific disciplines and/or stakeholders, such that integrated
insights are made available to decision-makers.
Integrated Assessment is an iterative, continuing process, where
integrated insights from the scientific and stakeholder community are
communicated to the decision-making community, and experiences and
learning effects from decision-makers form one input for scientific and
social assessment. Although participation of stakeholders is not a necessary
prerequisite, the conviction in the IA community grows that participation of
stakeholders is a vital element in IA. The engagement of non-scientific
knowledge, values and preferences into the IA process through social
discourse will improve the quality of IA by giving access to practical
knowledge and experience, and to a wider range of perspectives and options.
Integrated Assessment attempts to shed light on complex issues by
illuminating different aspects of the issue under concern: from causes to
impacts, and from options to strategies. IA has been widely applied in the
global change research area. IA emerged as a new field in global change
research because the traditional disciplinary approach to global change
research has been unable to meet two significant challenges central to
understanding global phenomena. The first challenge is the development of
an adequate characterisation of the complex interactions and feedback
mechanisms among the various facets of global change. Such feedbacks and
interactions are defined away or treated parametrically in traditional
disciplinary research. The second challenge is that of providing support for
public decision-making. IA offers an opportunity to develop a coherent
framework for testing the effectiveness of various policy strategies, and
estimating trade-offs among different policy options.
Performing IAs has a number of advantages. In general terms, IA can
help to:
put a complex problem in the broader context of other problems, by
exploring the interrelations of the specific problem with other issues;
assess potential response options to complex problems. This may be, but
not necessarily, in the form of cost-benefit and cost-effectiveness
analysis;
identify, illuminate and clarify the different types and sources of
uncertainties in the cause-effect chain(s) of a complex problem;
translate the concept of uncertainty into the concept of risk analysis, to
assist in decision-making under uncertainty;