SciAm video whiffs it on this extinction event

Smilodon at the Page Museum at the La Brea Tar Pits

Kitty. Victim of the late-Cenozoic extinction at the Page Museum in Los Angeles.

I usually like Scientific American’s short science explainer videos, but this one — Instant Egghead – Are We Facing the Sixth Mass Extinction?” — bothers me for a few reasons.

Fred Guterl starts off by saying that we don’t know yet whether our current extinction event qualifies as a “mass extinction.” It’s a bit of a semantic question, as the threshold for what constitutes a mass extinction is debated, and some rankings put different events in the top five. But let’s just take Guterl’s statement as meaning “we don’t know whether this current extinction is as big as the really big ones we’ve had in the past.” It’s an excellent point. It’s become received wisdom among a certain crowd that we’re facing Big Dieoff 6.0, and reminders that this isn’t necessarily any worse an event than, say, the extinctions at the end of the Eocene are always good. Not that the end-Eocene extinctions were a kitten romp.

The video goes off rather quickly, though, starting with the quick “citation” of a UNEP estimate of up to 200 species extinctions per day, which seems to have been taken urban legend style from an estimate Norman Myers made in the 1970s. Myers gave the range as 50-200, and he was saying 50 in 2006. We’ve seen a lot of estimates by different biologists. In 1993 E.O. Wilson offered an estimate of 30,000 species per year going extinct, about 85 a day. It depends on what models you use, and those models are the topic of debate.

Still, that’s more an editing quibble than anything. Few maintain that species aren’t going extinct faster than is “usual” for the Cenozoic.

There are a couple other WTF moments in the video, chief among them the statement that the end-Permian extinction was caused by Siberian lava flows igniting large coal deposits, creating a atmospheric CO2 spike “on the order of what we’re seeing today.” There’s certainly lots of evidence to support the idea, but it’s not a slam dunk, and other mechanisms remain possible.

There’s also an interesting mention of passenger pigeons that goes nowhere. In the context of species extinction rate models Guterl mentions that there was a population of billions of passenger pigeons in North America for who knows how many millions of years, and yet only two fossils of the species are known. And then he drops it, not explaining the fact’s relevance. I mean, I got there, and you probably did too — it implies that for each species we know went extinct back in the day, there were likely many we don’t know of whose fossils we have not yet found. What that implies in terms of past extinction rates I’m not sure: it’scertain that species we don’t know of  went extinct and aren’t counted in the totals, but it would seem equally plausible that species we don’t know about survived the extinctions of the past, or that species we do know about that we now count as victims of mass extinctions actually survived those extinctions but left no trace for a few millon years afterward. Perhaps someone here with a better understanding of paleontology can help me out with this. In any event, it would have been nice to have Guterl finish his thought there.

My biggest problem with the video, though, is in Guterl’s suggestion that our changing the atmosphere’s composition — referring to the end-Permian extinction, as well as the “Great Oxygenation” of the Paleoproterozoic — is what’s got scientists worried about mass extinction these days, given that we happen to be adding CO2 to the atmosphere faster than the Siberian Traps did 252 million years ago. And scientists are indeed worried about the effects of climate change on biodiversity.

But scientists working on studying and preserving biodiversity — which after all is the positive way of saying “not having a mass extinction’ — are worried about a whole lot more than climate change. We could completely solve the atmospheric CO2 overburden on Tuesday and still be faced with an extinction crisis as we plow up grasslands, cut down forests, bottom-trawl the oceans, and build new sprawling cities on land that once supported wildlife.

The IUCN identifies habitat loss as the main threat to 85% of the species it lists as “Threatened” or “Endangered” on its Red List. The Red List includes 391 terrestrial plant species of all threat levels described as potentially threatened by climate change or severe weather, compared to 5,582  that may be threatened by human disruption of their habitat. The equivalent numbers for terrestrial animal species are 1,991 potentially threatened by climate change and 13,388 by habitat disruption.

There are errors inherent in the IUCN data that stem mainly from lack of resources to assess species, but the implication is clear. Climate change is thought to pose a serious threat to many species. Human-caused habitat disruption is likely a more serious threat.

One of the problems I have with the mainstream environmental movement these days is that “environmental protection” has been conflated with “climate change mitigation.” You can search environmental publications in vain for a long time for mentions of other issues. When I started editing environmentalist publications in 1992 — the year of the first Earth Summit, in Rio — public attention was about evenly divided between the importance of preserving biodiversity and the threat of climate change. You can see evidence of this in the newly revamped Google Ngram viewer, by comparing mentions of the relevant phrases in books archived by Google as a function of time:

Expressed as a percentage of text in all books in the database, “biodiversity” peaks relative to “climate change” in 1997, then actually starts to decline in 2003. “Climate change” gains the lead the year the Al Gore’s movie came out. Google’s data runs until 2008. My personal anecdata would suggest that the lead “climate change” started developing in 2006 probably grew dramatically after 2009, with biodiversity likely to catch up a little bit sometime next year due to renewed attention to the issue on the UN front.

The point is that environment has become synonymous with climate in many minds. Thinking of biodiversity as of secondary importance (at best) to climate change has resulted in proposals to stem climate change that would actually harm biodiversity. They include everything from seeding oceans with iron to cutting down rainforests for biofuel soy plantations to siting utility-scale solar plants on intact and biodiverse desert habitat when there are former alfalfa farms in the neighborhood.

By mentioning only climate change in a video that purports to address whether we’re facing a mass extinction, Scientific American helps promote this emphasis on climate change — which is obviously a huge threat — to the exclusion of the greater causes of current extinctions. Yes, it’s a video lasting less than three minutes, but one could easily mention agricultural conversion and overfishing and forest clearcutting in a short video. They aren’t complicated concepts.

By all means, SciAm should rail against climate change. SciAm should persuade people to look at their carbon footprints, to demand changes in the way we run our industrial society, and to challenge the idiots in charge who’d deny any climate problem exists. But this was supposed to be a video on the current extinction event, and you somehow failed to mention the larger causes of that extinction. That does a disservice to SciAm’s viewers — and to the science.


  1. madscientist says

    I blame the Climate Change Bandwagon. It’s the Nanotech of our current era. Want funding? Gee, an awful lot seems to go into things like Climate Forecasting – maybe if we got the word “Climate” in our proposal we might get some money. Meanwhile, next to nothing is happening to address the real problem of global warming. Humans are such silly apes.

  2. chrislawson says

    There’s really only one major error and that’s the description of climate change as the main driver of modern extinctions instead of habitat loss. The other flaws in the video are due to over-reliance on one or two sources and failure to mention viable alternative hypotheses. This particular problem bedevilled the otherwise excellent Walking with Dinosaurs series: lots of perfectly good hypotheses but presented as absolute facts and with no mention of any supporting/dissenting evidence.

  3. Menyambal --- Sambal's Little Helper says

    I’d say that habitat loss isn’t the *only* other factor in extinctions. Some species have been simply killed off,through hunting or overfishing, while their habitat sits unchanged and empty.

    Besides, climate change would include habitat loss, wouldn’t it? If the climate changes, the habitat is lost, or at least uninhabitable, whether humans build houses in it or not.

  4. WhiteHatLurker says

    The passenger pigeon example seems to be the victim of a bad edit. I think they simply cut out the discussion explaining its relevance.

    I guess we won’t know how great an extinction event it is until we’re on the other side, as long as we’re around on the other side 8-)

    I like the cat picture, but is PZ getting soft on felines?

  5. unclefrogy says

    regardless of the precise details I do not here anyone trying to argue that we are not going through an extinction event or at least a bottle neck of considerable dimensions

    uncle frogy

  6. says

    Besides, climate change would include habitat loss, wouldn’t it? If the climate changes, the habitat is lost, or at least uninhabitable, whether humans build houses in it or not.

    Climate change will certainly harm habitat in ways we can and can’t predict. Some of the effect may be an erosion of habitat value rather than eradicating it. Even a habitat that’s stripped of 75% of its habitat value by climate change can still provide a bit of cushion as species adapt to a climate-changed world. Which isn’t necessarily true if we cut that habitat down because climate change will get it anyway.

    More on global warming and why it really is as important as habitat loss, something that will indubitably follow.

    The David Roberts TEDx talk video doesn’t seem to address the relative scale of the two (utterly intrerrelated) issues.

    No one’s saying climate change isn’t a huge threat. It just may very well not be the worst environmental threat we face.

  7. a_ray_in_dilbert_space says

    As a longtime slogger in the trenches of the climate wars, I agree with PZ:
    Climate change is just one of many potentially existential threats we as a species face. We cannot afford to ignore any of them.

  8. chigau (棒や石) says

    Perhaps you need to start all your posts with:
    in red.

  9. viajera says

    Hmm, that’s interesting. I’m out of the mainstream conservation loop, so I didn’t realize it had gone “All Climate Change All the Time.” My impression – and the impression I get from other academic ecologists / conservation biologists at conferences I attend – is that we’ve moved beyond climate change in many ways. Climate change is going to be terrible, but bottom line, there’s not much we can do about it. That’s up to the politicians and the policy-makers, and besides, even if we made dramatic change now (unlikely), we’re *still* going to lose a lot of species and habitat. I find that “global change” – which encompasses multiple drivers, including climate change and forest fragmentation – is the key buzzword for proposals, rather than just “climate change”.

    But we *can* do something about other global change drivers, e.g., forest fragmentation and – my pet issue – trophic downgrading / species interactions. You can buy up land and set aside reserves in areas that are predicted to have suitable climate / vegetation to support critical species in the future. You can manage top predators and large herbivores/frugivores to prevent trophic cascades rendering preserves uninhabitable, despite suitable climate. That’s where I’d like to see conservation focus.

    But that’s just me. And we’re dealing with a public who doesn’t even accept that climate change is *occurring*, let alone see that it’s basically a done deal already – a question only of degree (pun intended) of change. So we have a long ways to go.

  10. F says

    There is plenty of ignorant, phrase-spitting environmentalism that is problematic. Some people feel the importance without understanding much about it, and others are simply cultural bandwagon riders. So there is a lot of information, and a lot of targets for the denialists to mock, which is unfortunate. It’s a good thing that there are good scientists, science communicators, and communities like this one, which have their facts straight and a better understanding of the issues.

    Back in the seventies, it was just “pollution”. It was the major problem which was more readily addressable a and more understandable to more people. I think “climate change” (human-released CO2 and friends -induced) holds a similar position today. Deforestation held the main focus for a while as well. The problem is that these are expedient “single-issues” that are more useful socially and politically in an attention span starved world. My hope is that they are proxies for the more complete ball of wax.

    As far as habitat loss/altering the landscape and climate change both needing to be addressed, this is true. But the dividing lines are fractal. Climate change will cause habitat loss, but all habitat loss is not caused by, nor will cause, climate change. But we have been doing both for far longer than since the beginning of the industrial revolution. This has been happening at least since the beginning of the agricultural revolution (which still hasn’t ended, and which is part of the problem). Deforestation and the manipulation of freshwater systems has caused both habitat loss and climate change, and not only through the production or reduced sequestration of greenhouse gasses.

    One angle which might be taken, perhaps more appealing to atheists and secularists or the progressive religious, is simply to try and do away with the idea that humans are to have dominion over everything in the world. (Without getting all mystical, nature-worshipy, and New Agey. I guess this is why the religious who attend these words from the Bible, but who see the problems with this, want to look at dominion as stewardship which does not necessarily include using up every scrap of nature, but does include its protection.)

    Another angle is economic, and that is to stop looking at landscape unoccupied by humans as “undeveloped”, as if the land were in some “unused” state, doing nothing, and this needed correction. “Don’t shit where you eat” is a short and not necessarily sweet rubric which covers a lot of these things, assuming that the concept that a lot of what some like to think of as “progress” is will eventually be seen for the shit it actually is.


    WhiteHatLurker (and PZ, actually)

    I dunno, is that actually a feline or not? (Duh, never mind, it’s Smilodon, a Felid.)

  11. Justin says

    Climate change is THE most significant problem we face. And it’s not because of biodiversity loss (which is a serious problem), it’s because of reduced crop yields. We’re already seeing that with the massive drought in the US, and elsewhere.

    Not much you can do about biodiversity when the human population is starving.

  12. F says


    Yes, here in the Anthropocene, climate change is already occurring and will continue to do so. What we can do is to stop fueling it to make it worse. I’m not sure what is the percentage of people who think we can “reverse” or “stop” it somehow. Yeah, you’re right, we are already there.

  13. DLC says

    nah, he should end his posts with “I am Chris Clarke and I approved this message” . At least until after the elections.

    I didn’t approve your message, but I approve of it. rather a different thing.

  14. John Scanlon FCD says

    If you look here, you’ll see that mentions of the actual problem (rather than particular symptoms and mechanisms of damage) had already flatlined by the 80s, and then went into a slow decline.

    Oddly enough, it’s a problem that (unlike per capita fuel consumption or clearing for agriculture) we know how to reduce dramatically (ie by orders of magnitude), and which will also fix itself if we don’t.

  15. crocswsocks says

    “…cutting down rainforests for biofuel soy plantations…”

    Wow… that is… wow. Just… wow. Way to miss the point, everyone who thinks this is a good idea. Maybe we should cut down their houses first and see how they like it. We could also give some orangutans some viagra and set them loose on their families. Sounds horrifying, I know, but apparently these people are into horrifying ideas.

  16. bradleybetts says

    “They include everything from seeding oceans with iron to cutting down rainforests for biofuel soy plantations to siting utility-scale solar plants on intact and biodiverse desert habitat when there are former alfalfa farms in the neighborhood.”

    OK, being English this is a common problem I have with American literature and have been having for quite a while, and I was hoping someone could explain it to me… what the hell is alfalfa?

  17. slatham says

    Back in the early 90’s I wrote an essay for a university course in which I contrasted two historical ethics: “wise use” (Gifford Pinchot) and “preservationism” (John Muir/Aldo Leopold). Big deal, everybody has seen essays about that! But I wanted to make the point that each kind of “environmentalism” has shrunk back to more practically or easily defined objectives. In this evolution, the “wise use” movement has become the “ecosystem services” movement. I argued that rather than protecting for future volitional use, the bar had been lowered to protecting just what we need (what we currently use for human survival). On the other side, wilderness preservation including the goal of protecting unimpeded ecosystem processes has given way to “gene conservation”. Today’s environmentalist following this path would find captive breeding programs less indicative of failure than would her predecessors.
    I think what Chris is describing is mostly a shift in popularity among the majority toward the ecosystem services perspective. Biodiversity conservation (genetic conservation) is too esoteric for most people nowadays. Consumer society has convinced most people that parks are preserved for use by people. The ethics behind wilderness preservation and conservation of biodiversity are fading away from the popular conscience.