Print Page“Credit stacking” is a novel and significant development in ecosystem service markets whereby multiple, spatially-overlapping credits representing different ecosystem services are sold separately to compensate for different impacts. Concern with, and interest in, stacking has grown rapidly in the past year, and will continue to expand in the multibillion-dollar international market in carbon, habitat, and water quality credits. Environmental entrepreneurs see that stacking provides the possibility of new revenue streams from environmental credit sites, and regulators and policymakers are encouraged by stacking’s capacity to recognize multiple environmental benefits (as with REDD+). However, scientists are concerned that because ecosystem functions are interdependent and integrated, stacking may result in unaccounted, and unaccountable, net environmental changes. In opposition to stacking, “bundling” has been defined as the practice of acknowledging the multiple services at a credit-generating site while still requiring them to be transacted together as a unit, rather than separately as with stacking.
Results/Conclusions
We discuss examples of credit stacking and outline the two major concerns which will challenge policymakers and scientists alike, while proposing definitions for conceptual clarity. We present and explain three different crediting systems that are currently being developed or used to market multiple ecosystem services from a single site, and discuss the ecological challenges of each. Lack of symmetry in the treatment of stacked compensation sites and impact sites may make functional gains more visible and easily-counted than functional losses. The regulatory challenges of overseeing multiple interrelated markets may be overwhelming. We recommend that stacking should be avoided until ecological assessment techniques can be developed which account for the functional integration of distinct ecosystem credits present on a conservation site.
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