Underlying the market-based approach are scientific studies linking the estimated impacts on biodiversity to certain
causes (e.g. the effect of pests on forests, of forests on air pollution etc.). We should recognize that
there are still many uncertainties regarding these links, which should be reflected in the reported
benefits; (4) The majority of the studies refer to marginal changes in local areas. At the same time
there are a few that value the broad scale of services provided globally. The numbers from the
latter studies are extremely high; (5) The purpose of many of the studies was to show that the
services provided by nature are significant and either merit protection (where biodiversity is
threatened) or merit expansion (where there is potential for it). Estimates of the ‘opportunity cost’
of coastal habitat, wetlands – i.e. what it would be worth if it were not conserved - are often much
lower than the value of the biodiversity services provided if it was conserved.