Where an environmental asset is not being brought or sold it is not easy to give it
a value. Non-market environmental valuation is widely practised (Haab and
McConnel, 2002). There have been efforts to focus accounting on those parts of the
natural environment which perform important and irreplaceable functions – critical
natural capital (Chiesura and de Groot, 2003). People tend to be unwilling to pay if
they do not directly benefit. Yet sometimes there are situations where people accept
a cost without much immediate personal benefit. For example, they may contribute
to wildlife conservation and few will ever set foot in Amazonia or Kenya. It is
possible for a population to spend large sums of money to support football, which is
not crucial for human survival, but balk at taxes to conserve biodiversity, control
soil erosion or pollution.