Geoscience Reference
In-Depth Information
The answers are hypothetical and do not correspond to actual behavior.
Additionally, people may exaggerate the values of saving threatened spe-
cies or ecosystems if they feel a “warm glow effect” about the subject—
for example, they may think of beautiful pictures of jumping salmon
that have no relationship with the actual fi sh involved. There are many
subjective biases that must be overcome.
Skeptics further point out that the numbers from CVM studies are
sometimes implausibly large. We can look at the results for the migra-
tory fi sh survey described above as an example. Median household
income in Washington at the time of the survey was $46,400, so the
value of the fi sh population was estimated to be 1.6 percent of income,
which seems a large sum. We might wonder what people would say
about other environmental issues. Suppose we did surveys on the value
of migratory birds in Washington, of other threatened species, of water
quality or air pollution in Washington, and of removing the dangers
from nuclear waste sites across the state. These might well elicit similar-
sized answers. We might further inquire into the value of remote sites
like Yellowstone National Park and the Himalayan glaciers, and about
Arctic foxes and polar bears. A good bet is that some creativity would
produce a total value from all these potential losses that was more than
household income.
If we go back and ask people what they would pay for all the envi-
ronmental issues combined, it seems unlikely they would pay anything
nearly as large as the sum of the individual answers. Or if they were
asked to vote in a tax referendum, they might well vote to pay nothing
at all.
My personal appraisal here is that CVM and similar survey-type
techniques are illustrative but too unreliable at present to be used for
assessing the costs of ecosystem effects triggered by the rising CO
2
concentrations and climate change. The two shortcomings discussed
above—incomplete scientifi c assessment of the risks and controversial
economic tools for valuation—indicate that we are a long way from
having reliable estimates of the economic impact for losses to wildlife,
species, and ecosystems to use in our estimates of the impacts of global
warming.
