I promised last week to add some concreteness to my controversial argument in favor of a kind of precautionary principle for human activities that pose risks of significant environmental damage. Specifically, I was arguing that we should be skeptical of attempts to re-engineer the natural environment along the lines of some grand plan, just as we should be skeptical of attempts to re-engineer the human economy along the lines of a grand plan. So what counts as “re-engineering” of nature? And how would a precautionary principle protect against it?
Introductions of alien species to “improve” the native environment are classic examples of environmental central planning. Here are some examples of such introductions:
- The small Indian mongoose (PDF) was introduced to a number of islands, from Jamaica to Hawaii, in the late 19th century in order to prey on rats, which damaged crops and were sometimes prey for poisonous snakes. However, the mongoose ended up not preying much on the rats, but on native wildlife instead, causing multiple extinctions. Moreover, the mongoose ended up causing more crop damage than the rats had.
- Multiflora rose was introduced to North America from Asia as rootstock for ornamental roses. It was also widely planted in the 1950’s and 1960’s when the USDA recommended it as a “living fence” for livestock farmers. It rapidly escaped into the wild, where its populations exploded. Today it is found in virtually every natural area in most of the eastern U.S. and Canada, where it creates dense, thorny thickets, shades out and kills the forest understory, and disrupts natural succession.
- Importation of ornamental or culinary species into North America was either probably or definitely responsible for the introduction of:
- American chestnut blight, which has caused the virtual extinction of the American chestnut.
- Giant hogweed, which has spread into the wild and can cause severe skin irritation and even blindness in humans.
- Common buckthorn, which creates monocultures where virtually no other living plant is found.
- Garlic mustard, a culinary herb, which is rapidly spreading across the eastern U.S. and “outcompetes native plants by aggressively monopolizing light, moisture, nutrients, soil and space.”
- Human-introduced cats and rats are responsible for numerous species extinctions in island environments. In urban areas there are often hundreds of feral cats per square mile, and cats kill hundreds of millions of birds and more than a billion small mammals each year, not to mention countless amphibians, lizards, and other animals.
- Asian bighead and grass carp were brought to the U.S. to filter aquaculture ponds. They escaped into the Mississippi River, where they have reproduced exponentially and are associated with declines in native species, and are now threatening to invade the Great Lakes. In Japan, an American fish, the bluegill, escaped from an experimental lake and have become invasive there.
Humans alter the natural environment for aesthetics, recreation, and the growing of food. Increasingly, this alteration involves the intense application of synthetic fertilizers and pesticides. Frogs are dying out around the globe due to the chytrid fungus, and new research shows that the agricultural herbicide atrazine, banned in Europe, is also responsible for major die-offs and deformities. Fertilizer runoff from farms has caused vast “dead zones” in the Gulf of Mexico and elsewhere.
Earlier, humans extirpated wolves and mountain lions from most of the U.S. because of irrational fears for human safety and more rational concerns about livestock losses. As a result, native deer populations have exploded, exceeding natural carrying capacity in some places. Deer starvation, the extirpation of native flora eaten by deer, and perhaps even the spread of chronic wasting disease can be traced back to this monumental re-jiggering of nature.
I do not claim that all human manipulation of the environment works to the detriment of humans, which would be ridiculous. In general, however, attempts to “plan” the environment harm the environment, in the sense that speciation declines and different ecosystems around the globe become more and more similar in species composition. Some environmental harm is necessary for human benefit, but we should also expect that environmental harms have unmeasurable costs for humans, most obviously aesthetic but also material (less systemic resistance to disease, new invasions, population crashes and blowouts, etc.).
Since we know that environmental harms are not properly priced in the marketplace (environmental protection yields positive externalities), some regulation of environmental harms or subsidy for environmental protection seems warranted on utilitarian grounds, and probably on non-utilitarian grounds as well (wildlife are perhaps best thought of as common property). Certainly, the sad history of species introductions implies that any new species introduction should be carefully assessed before being permitted – hence the idea of a precautionary principle. A reasonable precautionary principle might look something like this: “There exists a general class of activities, which have
consequences that are likely to be harmful in ways that are difficult or impossible to measure. When considering the costs and benefits of any particular activity belonging to this general class, we should try to include estimates of costs and benefits of this activity based on similar cases, even when the directly measurable risks of this activity are near zero.”
This principle could apply to economic central planning as well. Take the minimum wage for instance, which belongs to a general class of economic policies known as price controls. The predicted economic effect of price controls in competitive markets is well known. Even if the empirical evidence on the effect of the minimum wage on employment is mixed (as it is), we should err on the side of opposing the minimum wage, because it belongs to a general class of policies we know create deadweight losses in all but the most unusual circumstances. The evidence in favor of the minimum wage would have to be overwhelming to overcome our prior judgment.
Similarly, when the importation of a new species is considered or a new pesticide is brought to market, it seems reasonable to demand considerable evidence of these products’ safety and efficacy before we judge that the benefits will exceed the costs. It’s not just a private matter.