statements that link alternative trends in human drivers or alternative actions to limit these drivers to specific environmental changes. The Intergovernmental Panel on Climate Change (IPCC) Working Group III on mitigation of climate change (IPCC 2001c) is a good example. Assessments can also provide scientific evaluations of adaptation strategies, such as in the case of the IPCC Working Group II on impacts, adaptation, and vulnerability (IPCC 2001b). As with all these types of contributions, the ability of assessments to effectively link actions and consequences depends both on an adequate base of scientific knowledge and on policy actors willing to support the activity and consider acting on its results.
Assessments have the potential to help solve recognized, shared technical problems. If most or all members of a relevant decision-making body perceive themselves to have a specific, shared problem, an assessment can make a significant contribution by bringing the principal parties together to find common technology options and solutions that solve their problem. An example is the Technology and Economic Assessment Panel (TEAP) that provides technical advice to the Montreal Protocol regarding alternatives to ozone-depleting substances.
Assessments have the potential to help identify and clarify key policy-relevant questions or research priorities. If the policy-relevant questions are vague or confused, instruments and models give conflicting results, or there are other serious conflicts in the field, assessments can provide disciplined settings to force confrontations between contending claims, sharpen disagreements, clarify incompatible terminology or concepts, and develop a research agenda to advance knowledge on key policy-relevant questions. Examples of assessments that have made contributions of this sort include IPCC’s Working Group I report (IPCC 2001a) and the Arctic Climate Impacts Assessment (ACIA 2004).
Assessments have the potential to demonstrate that a policy is providing environmental benefits. For example, the process assessment of stratospheric ozone assessment conducted under the Montreal Protocol provided evidence that the new policies were effective in reducing negative impacts on the ozone layer.
The context for any global change assessment has two primary components: (1) the scientific context, which concerns the state of relevant knowledge to be assessed; and (2) the policy and political context, which concerns the state of relevant policy debates and decisions that the assessment seeks