‘This is a wonderful book that should be on the desk of every architect and planner. It shows how

Contingent valuation
: People are surveyed about what they would be willing to pay 
for something like an ecosystem – or to be compensated for sacrificing it. ‘National’ parks, 
however, need samplings of the whole population of the country, as they belong to all citizens.
Such surveys have made decision-makers more aware of the full extent of bequest, existence 
and option values. They have been used to justify the removal of dams or to increase the 
environmental flows of (dammed or diverted) rivers. However, they only weigh people’s eco
-
nomic values, not the functional values of eco-services. Biases can also be created that can 
work both ways:
• 
People will inflate the value that they would actually be willing or able to pay. This is 
called the ‘Halo Effect’. Generally people have said they would pay more for ‘clean’ 
products than they actually do.
2
• 
It assumes people decide about the economic worth of some aspect of nature without 
knowing what will happen in the wider environmental context.
Contingent choice
: These surveys ask people how they would rank two or more actions, 
policies or programmes. This can also be a means of determining the most politically accept
-
able among environmentally harmful options.

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331
Boxes
Box 43 Problems with Pricing Eco-services
• 
We cannot measure the ecological base because it represents the whole life support 
system. Thus its value is infinite. We cannot even measure the eco-services it provides, 
because these are an inextricable part of the intricate web of nature. Their protection 
currently relies largely on their relevance to economists’ frameworks.
• 
Prices are a reflection of the ‘ability’ to pay and thus power relationships. For example, 
some women in developing nations sell body parts for very small sums of money to 
feed their children. This does 
not
mean that they do not value or need their kidneys. By 
analogy, ecosystems are the kidneys and lungs of the planet.
• 
Prices fluctuate according to socio-political variables and other factors that affect supply 
and demand. Some resource development interests are virtual monopolies or cartels 
that can limit the availability of raw materials to increase corporate access to public 
resources through scare campaigns about resource shortages.
• 
Communities may willingly sell off natural areas despite their recreational or wilderness 
values, expecting to be able to travel to enjoy other people’s forests. The remaining 
natural areas will eventually be over-used, even if through eco-tourism. Due to their 
scarcity, charges will be applied to access the public estate, which will exclude the poor. 
• 
Prices cannot register the need for ecosystem integrity. Ecosystems are self-managing 
only if the area allocated to them is large enough that they can continue to function as 
an integral system. Smaller areas will not have the ecological resilience to survive due 
to feral invaders, fires or species extinction triggered by disease.
• 
Wilderness areas can be too prevalent to have economic value one day, yet become too 
small to survive when critical ecological thresholds are crossed. The value of resources 
only needs to exceed the value of the wilderness areas containing them briefly, as in war 
time, for them to be irreversibly lost (eg dams change ecosystems forever).
• 
Eco-services go up in value as they become scarce, but so do mineral resources. When 
these areas are scarce enough to have a high conservation value, the value of the 
resources they contain (such as minerals and timber), will also go up accordingly.
• 
Marginal analysis is not contextual (and arguably excludes whole systems issues), so it 
is inconsistent with design. For example, it cannot deal with larger forces that affect 
supply and demand, such as global warming or chain reactions to environmental shock.
• 
Prices cannot reflect the infinite value of the life support system. Market prices can only 
indicate a small change in ecosystem services, not a total collapse. For example, even if 
water prices were high, prices could not prevent a global shortage of potable water.
• 
Discounting allows the value of nature to be reduced over time even though it becomes 
scarcer. This is contrary to the belief that the market will protect resources because 
prices will go up as nature becomes scarcer and is therefore more highly valued.