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Climate change, personal experience and the vagaries of memory

Looks the same to me… our personal experiences are not the best indicators of change. P León/flickr

We see it in the media all the time.

Regular beachgoers who see no evidence for sea-level rise, farmers trusting long-term experience over Bureau of Meteorology forecasting, Antarctic sea-captains whose memories of pack-ice from years past conflict with reported trends in ice-contraction.

It all provides grist to the mill for those who are sceptical about the scientific basis of anthropogenic global warming.

But how reliable is our personal experience when making decisions about climate change?

Decades of research in psychology has documented the vagaries of memory: the biases that can creep in when we try to recall information, the limited capacity of memory, the greater influence of recent events on recall – the list goes on.

These issues loom large with respect to climate change. Not least because to make informed judgments about the state of the climate, one needs to consider data from a wide range of locations – not just from the perspective of one individual – and over periods of time that typically exceed those for which human memory can be considered reliable.

Biased memories

In a 1997 study, American farmers were asked to recall significant rainfall and temperature events from the growing season of the preceding seven years.

Farmers who believed that the climate was changing in their region recalled temperature and rainfall trends consistent with this belief. Those who believed the climate to be static recalled temperatures and rainfall consistent with an unchanging region.

Our prior expectations and beliefs can influence not just the events that we recall, but our interpretation of their significance.

Fluctuating beliefs

It is not just recall that can be affected – even current experience (e.g., the weather outside) can have an impact on our beliefs.

Consider the following two scenarios.

Imagine that you are relaxing in a tropical paradise with the sun blazing down, your tan improving nicely, and the thought that perhaps it is time for yet another dip in the pool to cool off.

Now switch to a scene where you are standing freezing by the side of the road, waiting for a never-coming-bus wishing you’d worn that extra thick overcoat to ward off the sleeting rain.

If you’d been asked in these two situations: “How convinced are you that global warming is happening?” your answer should not depend upon the circumstances.

But it appears, at least for some people, that it is. This year, researchers found that participants showed elevated levels of concern and belief in global warming when they perceived the outdoor temperature (at the time when they answered the survey) to be warmer than usual.

Such results provide a salutary warning to those who raise doubts about the science of AGW on the basis of personal perceptions that “everything appears to be alright” or “nothing has changed”.

Negative experience, positive outcomes

Some unlucky people are rapidly disabused of the idea that “everything is alright” when they suffer the impacts of extreme climate events (floods, droughts, tornadoes, etc.).

But does this negative experience change attitudes and beliefs?

An intriguing recent study hypothesied that the observed reluctance to engage in efforts to mitigate climate change might be driven in part by the lack of personal experience (as per our beachgoers and sea captains) – and that therefore those unfortunate people who did have personal experience might be more likely to endorse mitigation strategies.

This is indeed what they found.

UK residents who had been severely affected by floods expressed more concern over climate change, saw it as less uncertain and felt more confident that their actions could have an effect on climate change.

Even more importantly, they exhibited greater willingness to save energy to mitigate climate change.

Combining experience and description

Making up one’s mind about climate change and the need (or not) for action requires integration of our own experience with the information contained in the numerous reports and reviews of climate change science.

This is no easy task.

Obtaining information in these two different ways can have a marked impact on the choices we make - such as whether or not to endorse a carbon tax.

But we must be aware of the limitations of experience and not shy away from the advantages of statistical models and descriptions of phenomena.

The reluctance of some people to accept the predictions of climate models or to dismiss analytic approaches to understanding climate is reminiscent of another venerable debate in the psychology of judgment.

In 1954 Paul Meehl created controversy by showing that simple statistical models could outperform the predictions of many clinicians, in for example, the diagnosis of mental disorders.

The superiority of these statistical techniques has been corroborated by hundreds of studies in diverse contexts.

Two key factors leading to the superiority are, first, that a statistical method will always arrive at the same judgment for a given set of data. Humans, on the other hand, are susceptible to the effects of fatigue, information presentation (framing), and recent experience.

Second, humans are often exposed to a skewed sample of evidence – like our beachgoer visiting only one beach – making it difficult to assess the actual relation between variables and a criterion of interest.

Thus while the evidence before our eyes (or the temperatures that we feel) may seem to conflict with what hear and read about the globe warming up, we should be sanguine about relying solely on our own experience when making an informed judgment.

This article originally appeared at Shaping Tomorrow’s World.

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