Improved assessments of subsurface projects: Systematic mapping of geosystem services and a review of their economic values.

Awareness of the subsurface and its multitude of resources is generally low and decisions on access to subsurface resources are often guided by a 'first come, first served principle'. Although not yet fully developed, the concept of geosystem services has been put forward to make subsurface resources more visible and acknowledged in decision-making. This study (1) illustrates a systematic mapping of effects on geosystem services using a process-oriented perspective in two conceptual case studies; (2) translates the mapped effects into costs and benefits items in a qualitative cost-benefit analysis (CBA) context; and (3) presents a systematic review of economic valuation studies of geosystem services to investigate the available support for a quantitative CBA. The findings suggest that systematic mapping of effects on multiple geosystem services can inform different types of assessment methods and decision-makers on trade-offs and provide a basis for well-informed and responsible decisions on subsurface use. Combining such mapping with a CBA can further strengthen decision support through indications of the net effects on human well-being. However, although economic valuation of non-market geosystem services is possible using established valuation methods, such studies are scarce in scientific literature. Thus, although a CBA can provide a basis for supporting decisions on subsurface use from a consequentialist perspective, full quantification of all effects may require great efforts, and it needs to be complemented with other methods to capture the full range of values the subsurface can provide. This study also highlights that depending on the context, supporting and regulating geosystem services can be either intermediate or final services. Therefore, if geosystem services are to be included in the abiotic extension of CICES, in which supporting services by definition are excluded, reclassification of the supporting geosystem services should be considered not to risk being overlooked in economic valuation and CBA.