Integrated assessment modelling

Integrated Assessment ( IA short, dt Integrated Assessment or Integrated Assessment ) refers to procedures especially in environmental sciences, the interdisciplinary merge knowledge from different areas of expertise, examine and evaluate the results with respect to alternative courses of action and represent. IA aims to complex problems as completely as possible cause - effect chains to capture. To use this usually come integrated assessment models (IAM, dt Integrated assessment models ), the models of different disciplines try to integrate them into a consistent overall model. Integrated Assessment is not a clearly defined term, many former research approaches can be subsumed.

Has gained particular importance in the analysis of the consequences of global warming and climate policy approach. The application of IA to other problems in environmental sciences are often referred to as Integrated Environmental Assessment ( IEA), the models accordingly as Integrated Environmental Assessment Model ( IEAM ).

Objectives and methods

Integrated Assessment is often very generally described as an iterative process that starts with a concrete policy issue is made ​​clear in a cross from the course knowledge and models about various natural and social science disciplines, and integrated the results for policy decisions to be treated. The aim is compared with approaches from only one discipline to create added value and decision-makers to provide additional information. In contrast it is not a priority to win in each discipline or to develop new knowledge about the specific issues of the assessment beyond, generally applicable models.

IA will usually integrate causal effect chains including important feedback, schematically as:

Other dimensions of integration are the stakeholders that are involved in the process, and the different orders of magnitude. Using IA examined problems are often long-term and wide-ranging, sometimes regional and medium-term.

Integrated models are used here to examine the consequences of political action or to determine optimal actions and also during the process to improve the understanding of the actors themselves. Due to their complexity IAM are mostly implemented as simulation models. In addition, and not accessible to the modeling areas are participatory methods are used, such as focus groups or expert panels. IAM are often modular and contain, often simplified, partial models from different disciplines.

Uncertainty is an important problem in IAM. A higher level of detail may be of some help, but leads to longer terms of simulations and, because of additional parameters, to more elaborate sensitivity analysis. It is often attempted to systematically determine the possible outcome spectrum, which only in the not too detailed models is possible. Differ This, together with different backgrounds and perspectives of modelers different models on an issue often strong in what aspects they ever consider formally and in what detail.

An important distinguishing feature of IAM is the type of integration policies. For example, for the IAM of global warming:

  • Means of externally given scenarios, for example, emission scenarios,
  • By specification of technology paths and their emission intensity,
  • Or as a result of the activity of agents in the model.


The emergence of the term in the 1970s is closely associated with new technical possibilities of the time, especially the computer simulation. The term was probably first used in the study of acid rain. The IA and thereby developed the RAINS model (Regional Acidification Information and Simulation) played an important role in the establishment of the Transboundary Air Pollution Convention, many countries oriented to the Additional Protocol to sulfur emissions to the recommendations of the IA.

Of special importance was IA mid-1980s to study the consequences and possibilities for anthropogenic global warming. IAM were used before the establishment of the Intergovernmental Panel on Climate Change (IPCC ) in 1988. During the negotiations on the UNFCCC United Nations ( adopted in 1992 ) were the results of the IAM in particular to determine "safe emission corridors" that would both avoid a dangerous rise in temperature as well as unacceptable respected economic disturbances. Too, on this basis, the emission reduction targets the Kyoto Protocol. middle of the 1990s, there were already more than 50 IAM. since then have seen increased efforts to make participatory approaches included in the IA of climate policy, for example in the EU ULYSSES project.

In the late 1990s and in the first half of the 2000s, initiatives such as the European Forum on Integrated Environmental Assessment ( EFIEA ) of the EU or the Integrated Assessment Society ( TIAS ) and journals have been launched. However, some have been set back by now.

Besides the problem of global warming IA is now used in a number of other issues, such as the management of land and water use or the environmental impact of chemicals.

Integrated Assessment of Global Warming

IA of global warming has three main objectives:

  • Possible future paths of human and natural systems coordinated to investigate
  • To gain insights into key issues of policy design options,
  • To prioritize research areas in order to better find robust policy options.

The integration helps to coordinate assumptions of different disciplines and introduce feedback in the analysis, which would be missing in the isolated study of individual fields.

IAM usually contain models at least as part of a climate model and an economic model as a general equilibrium model. They combine the damage caused by human activity emissions of greenhouse gases whose concentration in the atmosphere, related to temperature changes, the impact of global warming on ecosystems and people and their social and economic repercussions. Many IAM are optimization models that attempt to determine the emission path with the maximum total utility.

The Second Assessment Report of the IPCC is different optimizing and evaluative IAM climate policy.

The mid- 1990s, there were already more than 50 IAM for the investigation of global warming. One of the first was 1 IMAGE (Integrated Model to Assess the Greenhouse Effect ) of the Dutch National Institute for Public Health and the Environment (RIVM ). Other examples are the RICE and DICE ( William D. Nordhaus ) or WIAGEM ( Claudia kemfert ).

Many commonly cited cost-benefit models, for example, DICE, come to the conclusion that the optimal climate policy is to first do relatively little, too late act clearly. Some economists attribute this to questionable assumptions, for example, relatively high discounting future damage, a questionable assessment of non-monetary damages (such as the value of a human life, or biodiversity), the neglect of uncertainties, or overestimation of preventive and underestimation of adaptation costs. They consider it more useful to consider the IA climate policy as an insurance against the worst possible but unlikely event of a climate catastrophe and therefore preferable goal-and uncertainty -based models.