Setting Limits in Nature and the Metabolism of Knowledge : The Case of the Critical Load Concept

Abstract: In the 1980s, the earlier understanding that environmental problems are relatively simple was questioned. In order to handle the perceived complexity, several responses emerged. The Critical Load concept is a prominent example of such a response, which was introduced in thesecond-generation Protocols of the Convention of Long Range Transport of Air Pollutants (CLRTAP). The aim of this thesis is to analyse the dynamics of the ideational content of the Critical Load concept, using a discursive approach on policy. At the centre of the analysis are theories, ideas and knowledge claims about nature and processes in nature. The empirical material consists of policy texts produced by the Swedish Environmental Protection Agency (SEPA) and interviews with SEPA employees.The Critical Load concept can be interpreted as a meeting place where perceptions of different pollutants, objects in nature and scientific disciplines, meet and interact under the common view of nature as being robust within limits. Chemical mass-balance calculations oftransboundary air pollution in soils and forests dominate the operationalisation of the concept. The dominating chemical perspective has two origins. The first is the acidification concept, which has been the central issue of CLR TAP and has mainly been identified and discussed as a chemical problem. The second is the perception that chemical processes can be exactly measured in nature just as they can in the laboratory. Consequently, it is also generally assumed that estimates based on calculations of chemical processes fit well into the larger discourse of economically and ecologically efficient environmental policy-making within which the Critical Load concept has been situated. A change in the Critical Load concept, from exact mass balance calculations to risk analysis, could be identified with the introduction of new pollutants into the CLRTAP policy agenda. For certain types of pollutants even the possibility defining limits is denied. The conceptual change is here interpreted as a shrinkinglegitimacy of the concept, which also encompasses a weakening of the dominant view of nature as being robust within limits. It is, however too early to judge if this change will lead to larger discursive changes and a general refutation of the ideas that nature's limits are calculable and that such limits provide suitable foundations for environmental policy.