Public Perceptions of Global Warming

Richard Berk

University of California, Los Angeles, Department of Sociology

Los Angeles, California

What do people value about climate? How important is climate to things people value? There is use value as well as non-use value (i.e., for wildlife habitat, even if there is no personal contact or use, we feel better knowing it's there). Because there is no market for climate (not even a flawed one), we need to infer value. What is the best way to infer value? We can infer it from the behavior of individuals or we can set up a hypothetical market -- a game for people to play -- based on the concept of "contingent valuation" (CV) or "willingness to pay."

But what do people know about future climate? What can they know? We can "simulate" possible future climates and ask what people would be willing to pay to avoid certain outcomes. In framing the questions, we must be aware of social rhetoric (i.e., if we ask, "Is it a good idea to plant trees,?" everyone will say yes) and other response biases. How the questions are framed will, of course, affect the responses.

In order to begin to understand the value people place on climate, a survey was conducted in which the key question concerned contingent valuation. The survey asked, "Would you be willing to pay x dollars more a year for the things you normally buy in order to prevent this climate situation from occurring?" The amount of money, x, was varied randomly between $25 and $500 in $25 increments; temperature and precipitation outcomes were also varied, and the results were plotted. Four "parameters" of the resulting distributions were explored in detail:

  1. the mean
  2. the spread
  3. extreme values
  4. clustering of extreme values
The information we obtain from such surveys is important because eventually, we can feed survey data into climate models to simulate social feedbacks to climate. We can then feed climate model results back into more social surveys, and so on.

Not surprisingly, the higher the bid (x), the lower the probability that someone will accept it. Also not surprising, people regard big deviations from the climate they're accustomed to as unacceptable. In this survey, 600 interviewees evaluated 12 scenarios. Such a randomized experiment is the easiest way to get an unbiased result.

Conclusions

A general conclusion is that people act much as you would expect them to, but not nearly as fast. Another general conclusions is that there was complete disconnect between climate scenarios and policies. Other conclusions include:

A -- the public can consider complex issues -- they can "unpack" climate change
B -- surveys do not have to be written as sound bites
C -- responses to surveys on climate change depend on current climate conditions
D -- biography (gender, race, education level, etc.) does affect response
E -- temperature is more important to people than precipitation
F -- variability in weather does not seem to matter to people
G -- "small" changes in climate do not matter
H -- CV is not ready for prime time (not useful sensibly in policy arena)

In the group discussion, it was pointed out that response may vary depending on the weather at the time of the survey (i. e., like the 1988 summer heat wave) and media coverage. The effects shown in this survey are small compared to results of CV surveys dealing with other environmental disasters.

Some conference participants thought it was important to connect temperature scenarios to likely outcomes so people could make better decisions ( i.e., tell them how many elderly people would die as a result of the heat at a particular temperature, etc.). The participants advancing this viewpoint said that if people understood the dimensions, they could give us a better idea of what they really value. We need to present scenarios to people in terms they can relate to, these participants claimed, otherwise it is meaningless; we need to provide a frame of reference. Berk's response to this was that if you load questions with emotional stimuli, you get too much bias; everyone responds to certain emotional stimuli, such as old people dying.

What was the biggest surprise in this survey? It took big climate changes to budge people. And, it was pointed out, public perceptions are reality in social science. For example, one participant said, after the Valdez oil spill, the quality of the salmon was fine, but people wouldn't buy or eat it, because of the perception that its quality was low. In economic terms, the perceived quality was what mattered.

Table of Contents | AGCI Home Page