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I have been following the discussion with interest and am very pleased to have been given the opportunity to participate. Belatedly (I finally submitted my master's thesis last Friday), here are some thoughts on the discussion to date.
Dale and Ann both wrote about feedback as being important 1) in determining when we are pushing natural systems too far and 2) in supplying regulatory control to processes such as population growth (starvation being a particularly extreme form of negative feedback on population growth, for example). Feedback is an important component in regulatory mechanisms; however, for feedback to be useful in regulation, the information has to be presented in a time frame that allows for response and in a form that can be understood. Dale used the analogy of running into a tree - and using the branches as early warning signals of the impending collision with the trunk. But if the tree is a tall, skinny poplar the branches aren't very far from the trunk; as early warning signals they require pretty fast reflexes. Simplistic, I concede, but for many of the large-scale changes we are effecting on this planet, the damage is done by the time we notice it or at least by the time that we start to respond.
The question of information content is even more problematic, it seems to me. It is often assumed that change will be progressive - we add one more tonne of sulpher dioxide to the air and we loose one more species out of lake A. However, work by Holling, Schindler et al. on whole systems suggests that threshold changes are important in ecological systems. Incremental change in stressors result in incremental responses in the system up to a certain point and then one more increment in the stressor results in the shifting of the system to a dramatically new state - a shift that is not necessarily reversed by reducing the stressor by one unit. If these threshold effects (and I'm not sure that I count acid rain, ozone depletion, global warming, and intensification of urban areas as threshold effects - these all seem progressive to me, although they all may cause threshold effects in systems on which they act) are the norm in natural systems, then our ability to detect these thresholds and provide negative feedback to reduce the our progress towards them may be limited. The feedback when it comes may provide a very strong signal - but it may be too late to effect a correction except at great expense, if at all.
The other problem with feedback is that there are often conflicting feedbacks provided. In the case of the North Atlantic cod fishery, for example, one feedback (only detected belatedly because of problems in the models used to assess the fishery) was the declining size of the stock. A second feedback resulted from the overcapitalization of the fishing fleet. With fortunes invested in hardware, the fishers needed large catch allowances and pressured their politicians for high catch quotas. Given a population estimate with a high degree of uncertainty associated with it (a common occurrence in assessments of natural systems) and pressure for high catch quotas from the voters, the politicians listened to the latter feedback. How do we weigh feedbacks, prioritize them, integrate them?
This weighing of feedbacks becomes increasingly critical as the scientific uncertainty associated with the problem and the ramifications for change in human behaviour become greater. At a conference this summer, a speaker listed three global-scale problems facing us:
- 1.ozone depletion
- 2.climate warming
- 3.loss of biodiversity.
He noted that we were making reasonable progress in addressing the first, were starting to see action on the second, but had no idea where to begin with the third. These three issues define a gradient of complexity and an inverse gradient in terms simplicity of the required response. We have a fairly good idea what's causing ozone depletion, and we have a battery of technological fixes the implementation of which results in minimal shifts in our lifestyles (at least in the industrialized, wealthy countries). Global warming is more complicated in its causes and predicted effects, but reduction of fossil fuel emissions will help to solve the problem. Again, a technological fix - primarily (we improve scrubbers, produce cars that are more fuel efficient), but with a greater impact on our lifestyles (maybe we should drive less).
The causes of biodiversity loss are multiple - habitat loss, exploitation being the main mechanisms but the factors that cause habitat loss and exploitation include poverty, conflicting land use, unregulated landuse, population growth... and the interaction of all these and more. Did we loose species X because we cut down its forest habitat, or was it well on its way to extinction years earlier when we reduced the population size to the point that any small, stochastic disturbance would take it out? We are making less progress on biodiversity loss because it requires more than a technological fix, because we can't point to simple cause and effect relationships, often, and because biodiversity loss requires us to rethink the way we live on the planet. But in rethinking the way we live on the planet, all the other feedbacks (the economists have a whole host that show that continued growth is required) need to be balanced. I believe that this gradient of response to global environmental change relates to Ann's comment that we respond more easily to physical limits of the planet than to limits on human behavior. The problem is seeing and understanding those physical limits. These three global changes also illustrate the relationship between the extent of our response to the problem and the perceived risk to human well being. Increases in skin cancer rates are dramatic and direct links between changes in atmospheric ozone and human health. The links between biodiversity loss and human well being are less clear-cut, and therefore, biodiversity loss is perceived to be a less pressing concern.
A last point about feedbacks. Ann stated that there is a lack of feedback between the global economy and local consumption. I sometimes wonder, paranoid ecologist that I am, if the point of the global economy is precisely this decoupling - we won't know that we are running out of fish in Canada if they are shipped in from Asia in freezer ships. Because transportation technology, for example, has allowed us to greatly expand the area from which we collect resources, the feedback between resource use and changes to the system from which those resources are extracted is decoupled. The fisher trying to catch food for his family's dinner in Asia may notice a decline in his catch, but the North American eating imported Asian fish for her dinner, unaware of declines in the stock, decides to make this a regular component of her diet because the price is right and she likes the taste. Consumption of this sort is not local. I seem to recall Bill Rees saying that their calculations showed that BC couldn't support its own population in terms of food resources, let alone any of the other resources we consider key to modern life. How will global trade agreements affect our ability to reinstall feedbacks between consumption and natural system responses to consumption? I suspect that trying to make consumption more local (telling people to eat Canadian fish, e.g. by taxing fish from away, so that there is money to manage the local stock) will be perceived as an environmental tariff and struck down under GATT or Free Trade.
I'll stop rambling there. One specific question, in response to previous contributions:
Christine, I am intrigued by your discussion of the substitution of social capital for natural capital. Could you give an example? And perhaps suggest the potential for this kind of substitution in the largely resource-extraction-based Canadian economy?
Also, I'll weigh in in favour of cities (not suburbs!), but agree with Ann and Christine that dealing with the social issues associated with increasing urbanization are critical if these centres are to provide healthy living spaces. It pains me no end to watch suburbs sprawl out in an uncontrolled rampage on the countryside. As we cut down trees and pave the landscape with gay abandon, I am forced to conclude, yet again, that "plan" is a four-letter word in Canada.
- Date: Wed, 4 Jun 1997
- From: Nina-Marie Lister
- Subject: Following on economics...
Following on the economics train of thought, I am forwarding the following "news" item (or, I should say "non-news" to our group). I came across this summary piece on the economics of ecological services on one of my list-servers. It is very interesting to me that the original study appeared in Nature, which means it may have some potentially serious policy clout. However, it never ceases to amaze me how we need scientific/economic rational "proof" that nature has economic value, especially in light of the obviously untestable numbers cited below. And they called it "science".... but here's our long-awaited "proof" for all the sceptics out there [see below].
Cheers, and looking forward to putting faces to your names,
ECOSYSTEMS PROVIDE VALUABLE "SERVICES" WORTH $33 TRILLION, STUDY FINDS
The "services" of the earth's ecosystems "represent part of the total economic value of the planet," and are valued at $33 trillion per year, according to an article by 13 ecologists, economists, and geographers in Nature (May 15, 1997). "Because ecosystem services are not fully 'captured' in commercial markets or adequately quantified in terms comparable with economic services and manufactured capital, they are often given too little weight in policy decisions," the authors wrote. "This neglect may ultimately compromise the sustainability of humans in the biosphere. The economies of the Earth would grind to a halt without the services of ecological life-support systems, so in one sense their total value to the economy is infinite."
Among the 17 services provided by ecosystems are nutrient cycling, including "nitrogen fixation, N, P, and other elemental or nutrient cycles" (valued at $17 trillion); erosion control and sediment retention, including "prevention of loss of soil by wind, runoff, or other removal processes, and storage of silt in lakes and wetlands;" soil formation, including "weathering of rock and the accumulation of organic material;" pollination, including "provisioning of pollinators for the reproduction of plant populations;" biological control, including "keystone predator control of prey species;" and genetic resources, including "medicine; products for materials science; genes for resistance to plant pathogens and crop pests; pets; ornamental species; and horticultural varieties of plants."
According to an article about the study in The New York Times (May 20, 1997), "nature performs a long list of other economic services as well. Flood control, soil formation, pollination, food and timber production, provision of the raw material for new medicines, recreational opportunities, and the maintenance of a favorable climate are among them."
One way to put a value on such services, according to Newsweek (May 26, 1997), "is to figure out what it would cost to substitute technological fixes for what nature does. Substituting chemical fertilizer for natural nitrogen fixation, for instance, would cost at least $33 billion a year. Growing crops without soil by substituting the hydroponic systems beloved of urban gardeners would cost $2 million per acre in the United States."