If ecosystem services were actually paid for, in terms of their value
contribution to the global economy, the global price system would
be very different from what it is today. The price of commodities
using ecosystem services directly or indirectly would be much
greater. The structure of factor payments, including wages, interest
rates and profits would change dramatically. World GNP would be
very different in both magnitude and composition if it adequately
incorporated the value of ecosystem services. One practical use of
the estimates we have developed is to help modify systems of
national accounting to better reflect the value of ecosystem services
and natural capital. Initial attempts to do this paint a very different
picture of our current level of economic welfare than conventional
GNP, some indicating a levelling of welfare since about 1970 while
GNP has continued to increase31–33. A second important use of these
estimates is for project appraisal, where ecosystem services lost must
be weighed against the benefits of a specific project8. Because
ecosystem services are largely outside the market and uncertain,
they are too often ignored or undervalued, leading to the error of
constructing projects whose social costs far outweight their benefits.
As natural capital and ecosystem services become more stressed
and more ‘scarce’ in the future, we can only expect their value to
increase. If significant, irreversible thresholds are passed for irreplaceable
ecosystem services, their value may quickly jump to
infinity. Given the huge uncertainties involved, we may never
have a very precise estimate of the value of ecosystem services.
Nevertheless, even the crude initial estimate we have been able to
assemble is a useful starting point (we stress again that it is only a
starting point). It demonstrates the need for much additional
research and it also indicates the specific areas that are most in
need of additional study. It also highlights the relative importance of
ecosystem services and the potential impact on our welfare of
continuing to squander them.