Harte, John | October 20, 2015 | Leave a Comment Download as PDF

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A recent review of the fine new book on extinction (The Annihilation of Nature) by professor Gerardo Ceballos and Anne and Paul Ehrlich [1] illuminates two related problems in the struggle to achieve a sustainable society. The review itself, by environmental journalist Fred Pearce, is a collection of scientific errors. Pearce is famous for pressing the bizarre view that increasing population size is not a contributor to serious environmental problems, but increasing per capita consumption is. He refuses to see that the basic problem is the scale of overall consumption, and that is a product of the level of per capita consumption times the number of capita (population size). It is as if he claimed that the area of a rectangle is entirely the fault of its width –that length makes no contribution.

Pearce spends much of his review complaining about lack of knowledge of actual extinction rates, something not dealt with much in the book because the most recent studies make his discussion nonsense. [2]  There is no question Earth is entering the sixth great mass extinction event, and that human activities, including population growth, are the cause. Pearce’s lack of understanding about how scientists actually estimate species loss is illustrated by a quote from his review:

In the 1980s, ecologists developed a simple formula they called the “species-area relationship.” They argued that the number of species in a particular habitat could be derived from the area of that habitat. Big areas held more species, and if you halved the area, half the species would disappear. This formula became the basis for apocalyptic warnings about the impact of the massive destruction and fragmentation of rainforests, where a large proportion of the world’s species are thought to live.

I follow and have contributed to the scientific literature on extinction rates. No scientist has ever, to my knowledge, made the wacky assumption, above, that Pearce asserts is the basis for published estimates of future extinction. He is clearly out of touch with the methods scientists use to make such estimates, and resorts, instead, to making up arguments out of thin air. There are in fact ways to use species-area relationships to estimate extinction rates under habitat loss, but they are not at all like the way Pearce describes.

One of the many strange statements in the review provides a clue to how Pearce views the scientific process. Laughably, he asserts that one can’t claim scientifically that a beach is eroding unless you’ve counted the grains of sand. Would he assert that one can’t claim that a chemical reaction is occurring without counting molecules? His ignorance of science is profound.

Pearce claims that from the author’s perspective “the assumption is that the only way to protect nature is to sequester it behind fences in national parks where conservationists are king and the rest of us are excluded.” Pearce is apparently ignorant of the major leadership role Ceballos and the Ehrlichs (with Ehrlich’s former grad student, Gretchen Daily) have played in showing the opposite, with their compelling work showing how human-dominated landscapes can be modified to help preserve biodiversity.

Pearce seems to assert that invasive species will fill in for the losses that arise as a result of climate change, toxicity, and habitat loss. In fact, to that list of causes of extinction one should add invasive species, not subtract it! The increasing spread of invasive species such as kudzu (Japanese arrowroot) is displacing native species, not replacing the aesthetic pleasure and the ecosystem services that the displaced species provided. Such invasions provide disservices, not benefits. In that same category belong rats and cockroaches.

Pearce’s review illustrates two broad concerns about scientific literacy and the media. One is illuminated by the review, itself; some journalists fearlessly ignore their own tenuous grip on science. The other is even more serious in my opinion for it allows the likes of Pearce to think they can get away with the dissemination of scientific confusion. I speak of the failure of editors, publishers, and producers to recognize when they are unleashing on the public journalists who are way over their heads. Editors at Cambridge University Press exemplified this failure when they only asked economists, not scientists, to review the egregious book, The Skeptical Environmentalist, proposed by Bjorn Lomborg a decade ago. Their lack of understanding of science was so deep that apparently they did not even perceive the need to bring in scientific review. The deeper issue here, of course, is the failure of general education to produce editors with the knowledge to know the difference between sound science and the kinds of mangled logic and scientific misrepresentations that pervade Lomborg’s book and Pearce’s review.

I urge everyone to read the gorgeously illustrated book by Ceballos et al.  It is a treat for the eyes, and the bitter medicine of truth for the mind.

John Harte is a Professor of Ecosystem Sciences at UC Berkeley

You can learn more about the The Annihilation of Nature through the MAHB Library here.

[1] Fred Pearce, The Annihilation of Nature: The Siege Approach to Conservation.  Los Angeles Review of Books.  September 16th, 2015

[2] Ceballos G, Ehrlich PR, Barnosky AD, García A, Pringle RM, Palmer TM. 2015. Accelerated modern human–induced species losses: Entering the sixth mass extinction. Science Advances 1:e1400253. Available through the MAHB Library here.

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  • JohnTaves

    The sad reality is that population scientists like the Ehrlichs and Salmony/Hopfenberg (see below) are just as bad as Pearce.

    “It is as if he claimed that the area of a rectangle is entirely the fault of its width –that length makes no contribution” — I agree that Harte is correct to state that Pearce is being ridiculous, but the population scientists are making a worse mistake. All population scientists refer to the population size, but not how many babies we average. A fine example is Ehrlich’s ludicrous, yet famous I=PAT formula. How many babies we average is an exponential factor that drives population so why does Ehrlich hide the thing that contributes exponentially to Imact? Similarly from this article Harte writes: “times the number of capita (population size)”. This is bogus for two reasons: 1) this speaks to nobody, and 2) the number of babies we average determines the child mortality rate.

    Re: 1) If a scientist pointed out that the victims of the Titanic disaster died because of gravity, that scientist would be shown the exit. That scientist would not be wrong, but entirely useless because we cannot control gravity. We can control how many life boats are on a ship, so we mention the lack of sufficient life boats as a cause of death. So how does it make any sense for population scientists to constantly, reliably, religiously, refer to population size which nobody controls? No village, no county, no religion, no corporation, no nothing controls population size. The Chinese government doesn’t control their population size. They control how many babies one is allowed to have. Ceballos/Ehrlich write an article that says population growth/size is sending millions of species to extinction and Pearce says that population size is not doing this. Why do they and we care? Is Ceballos/Ehrlich really saying that we must not average more than 2 babies throughout the world? Is Pearce really saying that we must not limit the number of babies each has? If they are not saying that, then what is the point of this debate?

    Re: 2) The one and only consequence of averaging too many babies that
    mathematics/science/logic dictates is dead children. The formula is trivial. Children must die at the rate of (x-2)/x where x is the average number of babies adults have, in an environment with a steady subsistence supply. Countless other factors like adult life expectancy, age of the parent at birth, subsistence distribution can all affect the child mortality rate, but ONLY while those factors are CHANGING. If adult life expectancy is falling, then more children can live than dictated by (x-2)/x. Clearly adult life expectancy can only drop temporarily. Eventually it will reach a disgusting minimum, and then children must die at the rate of (x-2)/x. If the subsistence supply increases, then more can live. Clearly it too is bounded. Here we have a cause (how many babies you make) that directly controls the most horrid affect known to humans (killing children) and population scientists flat out ignore this concept. I can only assume that population scientists believe in magic that ensures we do not average too many babies. Below is a fine example of scientists that do believe in that magic.

    Salmony, in his comment below points to a paper by Hopfenberg and Pimentel. That paper is fundamentally sound in that it makes it clear that subsistence determines the population size. Of course it does. How else could the world work? Clearly Hopfenberg, Salmony, Ehrlich and Ceballos are all believing that each species magically limits their average number of babies in order to ensure we do not kill by averaging too many babies.

    For example in the Hopfenberg/Pimental article referenced by Salmony below, in the “Animal Data” section he is showing evidence of reduced reproduction rates tied to food availability and states that “These results demonstrate that food availability influences the population dynamics of a species”. This is rather banal. Of course the population size is limited by the subsistence availability. Of course reproduction will drop from what it otherwise would have been as more and more individuals are starving. Unfortunately his writing is trying to convince that it magically drops such that starvation does not happen. He does not explicitly state this, but he does state: “Starvation within the troop simply does not occur if the rate of food availability is held relatively constant.” This is bad science. To show that the troop is magically regulating their fertility to ensure they do not cause death by attempting to create too many babies, the scientist has to ensure that the bounds of the troop are well defined, not growing, with no net imports and zero emigration. I would take a long time to prove that they accomplished zero excess births. Go ahead and tell me the scientific rationale for how long you must have zero starvation related child mortality in order to prove they are regulating their births. The scientist would also have to make sure they do not overlook infanticide, kicking bad members out of the troop, and also the practice of allowing the runt to die. An instance of any one of those would wreck the proof that starvation is not happening and thus wreck the conclusion that magical regulation is happening.

    You need to know the difference between a “push system” and a “pull system” in order to spot that Hopfenberg’s suggestion that there is no starvation is really bad science. A pull system prevents pregnancies until someone dies. A push system just crams away and thus kills. A pull system is what we humans use for everything where we have a choice. We do not let someone into a full building until someone else leaves first. Reproduction is a push system. The monkey troop reference above, does not have a pull system. If they did, we wouldn’t bother trying to see if there is starvation, we would describe how the pull system works. Let me restate this in case you missed it. The scientist is looking for starvation and having failed to find it wants us to conclude there is a pull system. Failure to spot starvation cannot be used as proof of a pull system. It is trivial to not find starvation; just turn on the TV and watch a basketball game.

    The Hopfenberg paper makes another bad attempt to convince we have magically regulated our fertility. The quote from Kofi Annan: “The world has enough food. What it lacks is the political will to ensure that all people have access to this bounty, that all people enjoy food security.” is intended to convince us that if it weren’t for bad human behavior, we wouldn’t have starvation which proves that the mythical magical birth regulator is working. This is crap logic. That sentence is making excuses for starvation related deaths and attempting to turn those excuses into proof of the existence of a regulator that should ensure we don’t have these very deaths. The millions of people suffering starvation related child mortality is exactly the consequence we expect if we do not believe in the magical regulator. Further, notice how bad the excuse is. I will rephrase Kofi Annan to make it blatantly obvious: “Other people prevented the ones that starved from getting the food they needed.”

    Other people is exactly what is created when we average too many babies. These people did not die because monkeys beat them to the food. They did not die because lions ate first. These people died of starvation because other people beat them to the food that just grows on this planet. You cannot explain these starvation deaths without referring to other people.

    Population scientist’s focus on population size allows them to make poor conclusions regarding what happens when a population is at the limit. Hopfenberg’s paper states that “If food availability for the population is held constant and population increases continue at 1.4% per year (PRB, 2000), the reduction in per capita food per year is relatively small on average”. This calculation is correct, but utterly useless. We don’t do this. The fact that we have the highest average wealth or calories per capita ever achieved by humans and also still have groups of people suffering starvation related child mortality proves that this calculation is just fanciful nonsense. We certainly do share our food among our immediate group. That’s why 1 billion are chronically hungry. They are being brought down by the millions of children that must die each each year as a consequence of averaging too many babies. We don’t share from group to group.

    And let’s be clear about what Malthus wrote. His main conclusion was that there will always be people suffering for want of subsistence. This conclusion has NEVER been shown to be incorrect.

  • Steven Earl Salmony

    Could someone explain how human population dynamics are different from the population dynamics of other species?

    • JohnTaves

      Yes. We can directly control how many babies we make. Other species cannot.

      They cannot help but average too many babies, thus causing child mortality as a consequence of attempting to create too many individuals. We cannot help it either, unless we comprehend population science correctly and put that knowledge to good use.

      The science taught by the Ehrlichs, Malthus, and others is flawed.

  • stevenearlsalmony
  • jane

    I’ve just ordered the book from amazon uk and look forward to reading it, and to spreading its message.

  • jane

    The trouble is that writers like Pearce have gained much traction: it is now fashionable to dismiss population growth,especially in the media-which influences public opinion-and in the political and NGO sectors.
    Broadsheets like the Guardian promote the writings of Monbiot, Dorling and Rosling., who broadly agree with Pearce.
    Rosling was recently on the BBC, once again promoting his view that all we need to do is tackle poverty and the numbers will take care of themselves.
    Writers like these are given far too much plausibility, since their message is more palatable to the general public.
    As to Pearce’s claim that invasive species will take over abandoned niches so why worry? This is just daft: I ‘ve watched in dismay over the past decades as more and more British birds have all but disappeared, being replaced by ubiquitous pests like urban gulls and feral pigeons: this process shows no sign of halting.
    Rats and grey squirrels are making similar inroads in the mammalian world.

  • Steven Earl Salmony

    It is also pernicious for scientists to act as if they are willfully blind, hysterically dumb and (s)electively mute when presented with heretofore unchallenged scientific knowledge, the kind of outstanding research that realistically cannot be refuted. Take the ecological science of human population dynamics. When and where is this subject going to be openly examined?
    Steven Earl Salmony