One of the important goals of the next two decades is to achieve and maintain ecologically sustainable development of the biosphere. However, the management of ecological systems is rather difficult, largely because of uncertainties in long-term predictions of environmental and ecological behaviour. Thus, one of the objectives for integrated monitoring should be to provide early indications of impending changes so that mitigative actions can be taken. 

Also it may be important to be able to estimate in advance the detectability of the environmental changes that would ensue if a particular management strategy (e.g., a 30% reduction in sulphur emissions) were to be adopted. Monitoring systems have not traditionally been set up for these purposes. 

This paper includes a discussion of the factors to be considered in the design of early-warning monitoring systems, and gives some examples. One approach that appears to be particularly promising is that of identifying, quantifying and monitoring the stresses, feedbacks and component lags in the environmental-ecological system being studied.