« Car patrol vs. foot patrol | Main | The erotics of investing »
Jeff Sachs on biodiversity
His new book Common Wealth devotes an entire chapter to this important topic. Sachs writes:
The main lesson of ecology is the interconnectedness of the various parts of an ecosystem and the dangers of abrupt, nonlinear, and even catastrophic changes caused by modest forcings...It is a basic finding that biological diversity increases the productivity and resilience of ecosystems. With more species filling more niches in a given location, a biodiverse ecosystem is better buffered against external shocks in is more adept at cycling nutrients, capturing solar radiation, utilizing water resources, and preventing the takeover of the system by single predators, weeds, or pathogens. In other words, preserving biodiversity helps to preserve all aspects of ecosystem functions. Removing one or more species from an ecosystem, for example, by selective harvesting of trees or fish or hunted animals, can lead to a cascade of ecological changes with large, adverse, and nonlinear effects on the functioning of the ecosystem.
Now, loyal MR readers may remember that I am genuinely uncertain how much we should worry about the loss of biodiversity. I do know the following:
1. Many smart people who know much more science than I do are very worried about the loss of biodiversity.
2. Given that the human population has ballooned for the foreseeable future, massive losses in biodiversity are inevitable. The question is how bad the marginal losses will be, if we do not adapt policy accordingly.
3. If I had to conduct a debate and argue that the marginal loss of biodiversity was going to be a tragedy for human beings (obviously, I can see the loss to animals, and yes I do count that for something), I would not do very well. Yes Yana's children won't eat tuna and then I would sputter something about carbon and nitrogen cycles.
So OK readers, help me out. I've read Sachs's passage and I don't think I disagree with any of the claims in it. But I still cannot articulate to a skeptic exactly what marginal disaster will come if we do not take drastic action to preserve biodiversity.
Please use the comments to set me straight. What exactly will go wrong? And do not compare seven billion humans to pristine nature. Compare seven billion humans with bad biodiversity policy to, say, five billion humans with a pretty good biodiversity policy. What exactly is the difference? What are these costs as a percentage of gdp?
Please be as specific as possible; I genuinely would like to learn more.
Posted by Tyler Cowen on April 6, 2008 at 05:36 AM in Science | Permalink
Comments
Would an analogy help? What would happen to the economy if we wiped several businesses, even a few whole industries? After a few months/years other companies would took their places, but in nature the time necessary for replacement is tied to evolution, so we're talking about at least thousands of generations to relevant mutations create new species, depending of the niches wiped we may be talking about millions of generations. Loss of biodiversity would entail in a ecology recession that would probably be much longer than our recorded history is.
Posted by: Daniel Yokomizo at Apr 6, 2008 6:10:53 AM
Economically oriented discussions of biodiversity often call to my mind the legal concept of depraved-heart murder.
Definition -
: a murder that is the result of an act which is dangerous to others and shows that the perpetrator has a depraved mind and no regard for human [or any?] life. Depraved-heart murder is usually considered second- or third-degree murder.
Pronunciation: di-'prAvd-'härt-
Posted by: Robert Hahl at Apr 6, 2008 6:32:38 AM
The deliberate destruction of sparrows under Mao Zedong's Great Leap Forward (1958 - 1962) was meant to eliminate a pest that ate grain seeds. Initially harvests improved, but so did the reproductive rate of the local locusts and other insects, which were now relieved of large numbers of their main predator. A famine that killed 38 million people followed.
The deliberate introduction of rabbits to Australia in 1859 has been identified as the largest single factor in the extinction of one eighth of Australia's native mammal species. The rabbits' effect on large swaths of the landscape has had direct consequences for agricultural production, since the rabbits destroy vegetation that prevents soil erosion, and regulates the water cycle.
Posted by: Matthew Wittman at Apr 6, 2008 6:45:30 AM
Over-simplification of our ecosystem, where species that we can benefit from are domesticated, whilst the others are wiped out, makes our food chain extremely un-resilient to disruption. An optimally efficient system, with no complexity, leeway or feed-forward is fine in stable, predictable times but cannot deal with fluctuations such as crops being wiped out by infections - witness the potato starvation of Ireland, as an example of what happens when you've not got enough legs to stand on.
Secondly, a key lesson of ecology is that the law of unforeseen circumstances is extremely relevant here. Our interventions in ecology in the past have on occasion produced shockingly unexpected, disastrous effects. Based on historical performance, humans are not capable of accurately and safely interfering with what has been a largely stable, complex system that currently provides us with a hospitable living environment. Just like the economy, big shifts, whether designed by an academic or unfortunate consequences of urbanisation etc, can have ramifications way beyond our predictive ability. The conservative/"right wing" ecologist would argue that we are better off trying to preserve what we have and recede our interference in our ecosystem, than try to shape it around ourselves (whether deliberately or by negative externalities of unchecked human proliferation)
Posted by: Philippe Bradley at Apr 6, 2008 7:11:02 AM
A lesser consideration is the heart aching beauty of untouched areas: not just tropical rainforests, but places such as high mountain ecosystems, desert ecosystems, and temperate rainforests (Pacific Northwest, Tasmania, New Zealand). Zoos and parks are wonderful for teaching, but they are artificially maintained, and the loss of a species or two probably won't change the overall impact.
The interconnectivity of biodiversity means that we're not losing a species here or there, but losing the entire system. Ecology teaches us that when something is disturbed, the ecosystem moves on, and that "recovery" to an original state is often not possible.
Its not just not eating tuna, it is a loss of something of great beauty that cannot be recovered.
Posted by: at Apr 6, 2008 7:28:46 AM
Ecosystem services such as degradation of pollutants, disposal of wastes, natural production of food, raw materials and oxygen, protection of shorelines, etc. have been conservatively estimated to exceed in value all human production. Given that reductions in biodiversity reduce ecosystem services, that's a large price to pay. I don't know how large.
Another key point is that loss of biodiversity eliminates our options for restoration of particularly productive ecosystems. As well as economic activities associated with charismatic megafauna such as hunting and tourism. 50 years ago, who would have thought whale-watching would have become a big tourist draw for New England?
And most importantly, biodiversity is the library of genetic information which we are on the brink of exploiting. Every species is the end result of a huge period of natural selection to solve problems that we're only beginning to guess at in ways we do not understand except in a few simple cases. Plant breeders (like me) rely on searching this library for solutions to disease and pest problems that have arisen in uncountable natural experiments. Not to mention other sorts of useful variation. Loss of biodiversity is very much like burning many sections of the library, but preserving the best-sellers.
Libertarians haven't changed much on these issues in the past 20 years.
Posted by: Mike Huben at Apr 6, 2008 7:36:56 AM
Another very important point re biodiversity is tha we're still learning plenty from nature. New medicines are inspired by chemicals produced by animals, new materials come from research into insect exoskeletons, new developments in robotics come from studying ant colonies.
A loss of biodiversity results in a reduced field of information from which to draw inspiration and discovery.
It would be sort of like if physicists never looked up. Sure, they'd still have plenty of things to study, and plenty of advancements left to make, but there'd be all sorts of things they'd miss out on, because they never got the chance to see them.
In my opinion, this is even worse for humanity than the loss of environmental stability associated with reduced biodiversity. Creative thought is quite possibly the most valuable commodity I can imagine, and the fewer the sources of inspiration available, the less creative thought that will occur.
Posted by: Michael Woods at Apr 6, 2008 7:39:58 AM
Best reason I can come up with : There is no substitute to it.
Unlike oil that we can figure out how to replace, either as energy source or as material. Unlike mineral resources which can always be recycled.
Once you lose biodiversity, it's forever (economically speaking). So its market price should be astronomically high. Why isn't it? Because each specie has a huge potential value (medical, for reasearch, for its own sake, for who knows what else), but since we know so little about most of them, the market cannot put a price on it.
In a thousand years, when future generations have the technology to study, classify and exploit to its full the treasure chest of Earth's biodiversity, they will swear at us for the mass extinction we caused and didn't stop.
Posted by: Nicolas at Apr 6, 2008 8:39:34 AM
Most of the millions of species on the earth are limited to one or a few places and are closely related to other nearby species. Losing them is like losing small businesses in a recession. Perhaps one of them will be the next Hewlett-Packard, but otherwise their loss will have little influence on the world.
In a dynamic economic with lots of mobility, new businesses arise quickly to take the place of extinct ones. Obviously, this doesn't happen with species. The big question is how much this matters. Is it like the loss of languages, where the loss is mainly aesthetic (and it is notable how often political ecology arguments are aesthetic, e.g., "the heart aching beauty of untouched areas")?
Or are we losing irreplacable and tremendously valuable sources of medicines, materials fabrication techniques, etc? Are we "burning many sections of the library, but preserving the best-sellers"? No one really knows.
Posted by: Roger Sweeny at Apr 6, 2008 8:41:46 AM
These seem very weak arguments so far, and not really focused along the lines that Tyler asked for. Let me try.
Biodiversity is worth pursuing because the marginal cost is close to zero, when implemented as part of a broader program of modernization.
The #1 threat to biodiversity is agriculture. Better fertilizer, farming practices, irrigation, genetics, storage, transport, and so on will allow more food on less land. So will ending subsidies for biofuels and inefficient domestic crops (e.g. sugar beets). All of these policies are needed to improve agricultural productivity, and they have the side benefit of freeing up land for biodiversity protection.
The #2 threat to biodiversity is pollution. Experience over the past century has demonstrated that societies do not like pollution, and as soon as they can afford it they start doing something about it. So, maximizing GDP growth to shorten the transition time to prosperity will not only make people wealthier and healthier, it will allow them to afford a cleaner environment, which promotes biodiversity.
The #3 threat to biodiversity (and this is WAY down the list) is residential development. It's been argued on this forum that ending housing subsidies would be economically beneficial, and it would have some benefits for biodiversity as well.
See? Biodiversity can happen as an adjunct to policies that directly benefit humans.
Still feel like you need to implement a policy that is biodiversity specific? Fine. Put a tax on organic food to reflect the extra land that it requires. There. Don't you feel better?
Posted by: Bob Knaus at Apr 6, 2008 8:50:21 AM
Michael Woods, I am not so convinced of the 'inspired by nature' argument for biodiversity, for two reasons.
First, many if not most claims of 'Natura artis magistra' are more poetic than realistic. People just like to see a comparison with nature, and claiming your material is inspired by insects is a sure way to get into popular magazines. Medicins inspired by natural substances are rarer than people think.
Second, while I am sure there is a lot to learn from nature, I am not sure how much biodiversity we would need for that. If we do the worst we can to the world, there will still be more than enough ants left to learn our robotics and exoskeletons from.
Posted by: greatzamfir at Apr 6, 2008 8:52:28 AM
Not thinking marginally, but just to keep our options open, do we have any idea how much about biology we don't know and need to learn? Like what if we wiped out cats, and no longer had Toxoplasma, and it turned out to add important capabilities to our minds? Or what if they find the non-carbon-based life on earth they've been looking for recently (discarding the assumptions that would have made us miss it). We just have no idea what we're wiping out.
Posted by: Noumenon at Apr 6, 2008 8:55:28 AM
What's the difference between loss of biodiversity due to human behavior and loss of biodiversity due to nature? Millions of species have gone extinct for millions of years, and yet life goes on.
Posted by: Hei Lun Chan at Apr 6, 2008 9:09:07 AM
Once you lose biodiversity, it's forever (economically speaking). So its market price should be astronomically high. ... Because each specie has a huge potential value (medical, for reasearch, for its own sake, for who knows what else) ...
Yes, and no. Each species certainly has a value "for research." A future doctoral candidate can't study something that is no longer there. But that is true of anything that people change. No one can study what the ecological succession would have been on the place where my apartment now stands. If there are no white supremacists in a hundred years, no one will be able to interview them. That there will be a loss does not answer the question of what we should do to prevent it, of which things are worth how much to preserve.
Of course, one can give a blanket answer, "everything matters and should be preserved 'for its own sake'." Everything has a near infinite value. That is bracingly conservative, but most of us aren't conservatives (or Paretians).
Does each species have a huge potential medical value? Certainly not. Some probably do. Most probably don't. To try to save them all will certainly prevent some loss. Will it be worth the cost? To say it will is a statement of faith--and hope.
Posted by: Roger Sweeny at Apr 6, 2008 9:23:50 AM
This is key:
Removing one or more species from an ecosystem, for example, by selective harvesting of trees or fish or hunted animals, can lead to a cascade of ecological changes with large, adverse, and nonlinear effects on the functioning of the ecosystem.
When we think in terms of marginal changes we are implicitly assuming smooth functions, more or less predictable systems, etc. But we don't know that there are not discontinuities or sudden dramatic changes in velocity.
In other words, we don't know "exactly what will go wrong." Neither did Bear Stearns.
Posted by: Bernard Yomtov at Apr 6, 2008 9:56:46 AM
While it seems right not to "compare seven billion humans to pristine nature," why do you ask to compare "seven billion humans with bad biodiversity policy to, say, five billion humans with a pretty good biodiversity policy."
Why "five" and not "seven", if you want to be careful to "compare like with like", as, I think, Milton Friedman used to say?
Posted by: philippe coquoz at Apr 6, 2008 10:22:15 AM
The chief difficulty of pricing (the loss of) biodiversity marginally would appear to be complexity. You just don't know with what likelihood any given cocktail of species loss will set off a cataclysmic chain of events (much less which specific cataclysmic chain of events). It might be reasonable to start by assuming these probabilities are monotonically increasing in diversity loss, but getting more specific than that probably takes a Ph.D. in biology and a dose of divine intervention.
Posted by: Sean at Apr 6, 2008 10:42:14 AM
Martin Weitzman's QJE papers suggest a workable framework for pricing species of high marginal value. Since we cannot save them all, seems best to prioritize species and save as many as we can. I doubt we'll come close to the optimal MR=MC point so might as well start saving them now.
The biodiversity for prospecting literature does not suggest a high value (JPE papers forget the authors).
As for a John Krutilla-type option value, that's awfully hard to measure, where do you even start? Even bounds are unlikely to be agreed-upon.
Posted by: Jack at Apr 6, 2008 10:47:18 AM
I'm not so sure biodiversity cannot be created artificially, re: Craig Venter. But I agree it's best to start having a "better safe than sorry" approach to biodiversity.
Posted by: karl strom at Apr 6, 2008 10:49:40 AM
Tyler asks "What exactly will go wrong?"
That framing makes it impossible to give a specific answer. No one knows what exactly will go wrong. Folks who study ecosystems can point to examples where bad things have happened - crashes of systems where many species that are quite interdependent all go down. It's very hard to pinpoint a strategy for saving biodiversity to product maximum resilience and benefit for humans. It's easier to point to particular areas and say that resilience is dropping, but even then it's not so easy to figure out the cost of trying to reverse the trend, and the benefit of making the effort.
If we limit things purely to threats to humanity, I think that a lack or resilience in farm crops is a big one to worry about, since so much of our food stock comes from just a few grains (whereas in the past the number of grain plants that were eaten was much much higher). But what is the percent chance of widespread grain failure? And what is an allowable risk factor? (Should we use the Dick Cheney rule - one percent chance is enough to trigger action?)
Posted by: Curt at Apr 6, 2008 10:56:13 AM
One thing we should do regardless is create a databank to hold the genomes of every species. The economic/technical (i.e., non-aesthetic) value of every species other than our own is in its DNA, since only humans create and transmit learning/culture across generations.
As our knowledge grows, we will be able to exploit those genomes as we now do with the organisms themselves, finding their value for food production, energy production, medicines, etc.
We are on the verge of creating wholly synthesized life forms even today. These abilities will only grow.
Diverse ecosystems have many benefits as listed by the other posters, but that isn't the same thing as preserving individual species. In that sense, the analogy to losing a small business is a good one.
Posted by: Larry at Apr 6, 2008 11:02:03 AM
If I may change a few words in the Sachs quote...
for example, by selective [regulations] of [industries] can lead to a cascade of changes with large, adverse, and nonlinear effects on the functioning of the [economy].
For examples, see Smoot-Hawley, Europe's ban on GM imports and its effect on Africa, or on a smaller scale Tyler's cars versus foot patrols post.
There's all sorts of unanticipated secondary effects when a regulation is imposed on the economy (which similarly reduces socio-economic diversity) and it can similarly have cascade effects.
So for those arguing the precautionary principle for bio-diversity, will you also extend that argument to preserving socio-economic diversity?
I suspect not, because most of the commentors (cept for Bob Knaus) appear to be approaching this with an implicit prioritization of bio-diversity over socio-economic diversity. I find this confusing because by virtue of it having a more direct mechanism, the degree of socio-economic diversity should have a greater impact on humanity than the degree of bio-diversity.
Posted by: Jody at Apr 6, 2008 11:24:18 AM
Volatility is bad.
I think the argument for bad impacts is toughest to make persuasive because it hinges on the cousin of the Law of Unintended Consequences -- the Law of Unpredictable Changes. These changes could, in total, be really really really bad, yet since they are a set of consequences that are tough to pin down, they sound...airy -- without substance.
The feeling of "not knowing" doesn't change a lot of minds, unless perhaps they are particularly able to cross-apply concepts such as the Sharpe Ratio to...our collective ecological portfolio.
Posted by: infopractical at Apr 6, 2008 11:43:13 AM
1. Many smart people who know much more science than I do are very worried about the loss of biodiversity.
I don't know how to say this without sounding catty, so I'll just charge ahead. People who know a lot of science can also have a lot of emotional baggage.
Many people in the biological sciences are trying to understand how nature works, and humans are constantly disturbing their work, even destroying a good deal of their potential research base.
Imagine you and your friends are deeply concerned with understanding the game of basketball. But recently, people have begun mass disruptions of games, running onto the field at all sorts of times. Even if you manage to catch a game without disruption, you know tactics have changed to deal with that possibility. You will be extremely annoyed by the disrupters and will probably come up with all sorts of reasons why they are menaces to civilization--and you will believe them.
Or consider the controversy over deaccessions by museums, where museums sell off "surplus" art. Many art lovers just don't want to hear arguments about how this strengthens the museum's economic health, how it makes it possible to buy other more important works, etc. Art is good, and to get rid of it is bad.
Many who study nature have a semi-sacred attitude toward it. My Wilderness Society calendar for April has a beautiful picture of eroded sandstone in a prairie and the caption, "To see clearly is poetry, prophecy, and religion--all in one. John Ruskin" Destroying the sacred must have terrible consequences at some point in the future.
Posted by: Roger Sweeny at Apr 6, 2008 11:53:20 AM
Some definitions of biodiversity from a google search. When determining good vs. bad diversity policies, it makes sense to establish what biodiversity is. A definition that limits it to number of species will probably miss many of the values of biodiversity to humanity.
For instance genetic diversity within a species may promote survival of the species under changing environmental conditions (e.g. Peppered moth- genes in the population that resulted in black coloration promoted survival under polluted conditions, genes that resulted in light coloration promoted survival under conditions of better air quality). This form of diversity could be very important when dealing with crop disease.
Species diversity within a system may assist with retaining nutrients, prevention of sedimentation, maintenance of desired game or aesthetically-pleasing wildlife species, reduce risk of disease for humans (not as a source of medicines, but increased hosts for vectors-Google lyme disease/biodiversity), maintenance of desired plants species, etc.
Diversity of habitat types within an area generally promotes species diversity and at global scale different habitat type provide different services to humans (grasslands-grazing, forests-timber), partly because they contain different species adapted to those conditions.
Also, contributing to confusion is that biodiversity can be measured at different scales- local, regional, and global; and some of that may not scale up in terms of analyses.
I'm sure I've probably missed some of the variations of biodiversity. But, for all these forms of diversity some measure of economic value can be derived.
Googled Definitions of biodiversity (and there are several more variations of the same...)
Number and variety of living organisms; includes genetic diversity, species diversity, and ecological diversity.
biology.usgs.gov/s+t/noframe/z999.htm
The variety of life in all forms, levels and combinations. The term biodiversity includes genetic diversity, species diversity, and ecosystem diversity.[i]
www.csbsju.edu/environmentalstudies/curriculum/greenbuildingplan/Green%20Building%20Plan%20p12.htm
The number and variety of different organisms in the ecological complexes in which they naturally occur. Organisms are organized at many levels, ranging from complete ecosystems to the biochemical structures that are the molecular basis of heredity. ...
www.nsc.org/EHC/glossary.htm
The number of different species in a given habitat
prairieu.umn.edu/
The variety and abundance of species, their genetic composition, and the natural communities, ecosystems, and landscapes in which they occur.
www.governor.wa.gov/gsro/glossary/default.asp
Posted by: longleaf at Apr 6, 2008 11:58:27 AM
