The availability heuristic is judging the frequency or probability of an event by the ease with which examples of the event come to mind.
A famous 1978 study by Lichtenstein, Slovic, Fischhoff, Layman, and Combs, “Judged Frequency of Lethal Events,” studied errors in quantifying the severity of risks, or judging which of two dangers occurred more frequently. Subjects thought that accidents caused about as many deaths as disease; thought that homicide was a more frequent cause of death than suicide. Actually, diseases cause about sixteen times as many deaths as accidents, and suicide is twice as frequent as homicide.
An obvious hypothesis to account for these skewed beliefs is that murders are more likely to be talked about than suicides—thus, someone is more likely to recall hearing about a murder than hearing about a suicide. Accidents are more dramatic than diseases—perhaps this makes people more likely to remember, or more likely to recall, an accident. In 1979, a followup study by Combs and Slovic showed that the skewed probability judgments correlated strongly (0.85 and 0.89) with skewed reporting frequencies in two newspapers. This doesn’t disentangle whether murders are more available to memory because they are more reported-on, or whether newspapers report more on murders because murders are more vivid (hence also more remembered). But either way, an availability bias is at work.
Selective reporting is one major source of availability biases. In the ancestral environment, much of what you knew, you experienced yourself; or you heard it directly from a fellow tribe-member who had seen it. There was usually at most one layer of selective reporting between you, and the event itself. With today’s Internet, you may see reports that have passed through the hands of six bloggers on the way to you—six successive filters. Compared to our ancestors, we live in a larger world, in which far more happens, and far less of it reaches us—a much stronger selection effect, which can create much larger availability biases.
In real life, you’re unlikely to ever meet Bill Gates. But thanks to selective reporting by the media, you may be tempted to compare your life success to his—and suffer hedonic penalties accordingly. The objective frequency of Bill Gates is 0.00000000015, but you hear about him much more often. Conversely, 19% of the planet lives on less than $1/day, and I doubt that one fifth of the blog posts you read are written by them.
Using availability seems to give rise to an absurdity bias; events that have never happened are not recalled, and hence deemed to have probability zero. When no flooding has recently occurred (and yet the probabilities are still fairly calculable), people refuse to buy flood insurance even when it is heavily subsidized and priced far below an actuarially fair value. Kunreuther et al. suggest underreaction to threats of flooding may arise from “the inability of individuals to conceptualize floods that have never occurred . . . Men on flood plains appear to be very much prisoners of their experience . . . Recently experienced floods appear to set an upward bound to the size of loss with which managers believe they ought to be concerned.”1
Burton et al. report that when dams and levees are built, they reduce the frequency of floods, and thus apparently create a false sense of security, leading to reduced precautions.2 While building dams decreases the frequency of floods, damage per flood is afterward so much greater that average yearly damage increases.
The wise would extrapolate from a memory of small hazards to the possibility of large hazards. Instead, past experience of small hazards seems to set a perceived upper bound on risk. A society well-protected against minor hazards takes no action against major risks, building on flood plains once the regular minor floods are eliminated. A society subject to regular minor hazards treats those minor hazards as an upper bound on the size of the risks, guarding against regular minor floods but not occasional major floods.
Memory is not always a good guide to probabilities in the past, let alone in the future.
1 Howard Kunreuther, Robin Hogarth, and Jacqueline Meszaros, “Insurer Ambiguity and Market Failure,” Journal of Risk and Uncertainty 7 (1 1993): 71–87.
2 Ian Burton, Robert W. Kates, and Gilbert F. White, The Environment as Hazard, 1st ed. (New York: Oxford University Press, 1978).
Short answer: Yes. Forest fires are a natural and necessary part of forest development, and controlled burns are a long-standing indigenous practice. There are trees that will not start new generations without a fire; the seeds are dropped into the ashes, which let them crack open from heat, and they need the new sunlight access and nutrient access from the fire to get established. Fires also keep on top of pest populations and diseases, which can otherwise reach astronomical numbers and completely wipe populations. And if fires are frequent, each fire will stay small, as it will soon run into the area affected by the last fire where there is no fuel, and stop. The lack of fuel means they do not flicker high, and they do not run hot, so the inside and top of the larger trees remain fine. The contained area means they can be fled. So most mature trees and large animals will survive entirely.
The build-up of fuel due to fire suppression, on the other hand, leads to eventual extreme fires that are uncontainable, and can even wipe out trees previously considered immune to fire, such as sequoias, and reach speeds and sizes that become death traps for all animal life, as we saw in Australia.
Going back to indigenous fire management is all easier said than done, though; nowadays, human habitats often encroach so closely on wildlands that a forest fire would endanger human homes. And many forests are already so saturated with fuel that attempting a controlled burn can get out of hand.
But the fire management policies that got us to this point are one of many examples where trying to control a natural system and limit its destructive tendencies is more destructive in the long run, because the entire ecosystem is already adapted to destruction, and many aspects of it that seem untidy or inefficient or horrible at a glance end up serving another purpose.
E.g. You might think on the base of high underbrush promoting forest fires that we should cut down underbrush and remove dead trees from forests to limit fires; many humans thought that. This turned out to be a terrible idea, as this effectively devastated habitat for insects and small animals that burrow into or hide under dead wood, pulled nutrients from the ecosystem that was previously a closed circle, and removed fungi food sources, which in turn were crucial for tree networks that facilitate water trades during draughts and warnings from insect infestations, and removed perches on which animals could flee during floods. Historically, the healthiest forests were the ones we just left the fuck alone, and many interesting natural sites are the result of destruction, but then having humans pull out.
The current Chernobyl site is a startling illustration of this; humans fucked up the area, but then, we stopped messing with it, and it turned into a stable biodiversity hotspot despite the radiation; animals migrated there to flee humans, thrived and multiplied. We'll have to see how it gets through the war.
We also have nature reserves in Germany that are former military testing sites, that essentially got exploded to bits. The resulting habitat (lots of open ground with holes and shards and sand) was incredibly interesting for reptiles and insects, who also profited immensely from the fact that humans did not enter the area out of fear of being blown up by remaining grenades. Realising that having it grow back into a forest would ruin it for these animals, we decided to release natural grazers on there, which are wild and which humans cannot interact with. We got some leftover grazers which zoos said were hopeless and not reproducing no matter what they tried, so they would not be too sad if they got blown up. They did not get blown up. They are doing great. They are reproducing. The fact that nature thrives in areas which humans contaminated radioactively or littered with explosives, simply because we stop going there and messing with it, is simultaneously hopeful and depressing to me.
Forests doing fine if just left alone might change with climate change though; assisted tree migration will likely be needed here, as trees to not migrate the distances fast enough naturally to keep up with the rapid changes. This is currently being extensively trialed in Europe.
Dams are also bad for other reasons, because they tend to wipe out the varied shallow water, shore and flooded and then drying marshland habitat that is so crucial for biodiversity, for the survival of many birds, amphibians and insects that are endangered, and even fish; young animals often hide in dense vegetation in shallow water to hide from predation and stay warm, and a deep river with standing, deoxygenating water or fast currents is a completely hostile habitat for them; they reduce migration options for animals and hence genetic diversity as populations become practically isolated from each other, they interrupt nutrient exchanges.
Which is very unfortunate, because they are one of the leading options we have for storing renewable energy for winter, which is a massive hurdle, and getting renewable energy in winter without the insect and bird deaths current wind energy causes.
Sorry for the long rant this late. I really care about wild lands. They are incredible systems.