What Really Is the Worst That Can Happen?

Someone on the Facebook group “Global Warming Fact of the Day” (GWFotD to its Friends) brought up the famous and excellent Greg Craven video, and wondered why nobody had ever really answered Greg’s question.

So, what really IS the worst that could happen? Shouldn’t we calibrate our actions against that? Shouldn’t science try to answer that question?

This is especially true given the appearance of a community of people who believes that a climate-driven catastrophe is so imminent and so enormous that humans will be literally extinct within two decades. (Yes, some people apparently believe this so deeply that they express contempt for those who do not.) Can we refute them?

It turns out that it’s sort of an ill-posed question.

It’s certainly true that the whole ball of wax is at risk of being utterly ruined by humans. There’s some disagreement about how close to the edge we are and how much we can do about it. That it’s within our capacity to do that is no longer in doubt.

But there isn’t really a scientifically sound way to answer the question of what the worst case is.

For complex questions, rigorous thought is best done statistically. Are you talking about 99-to-1 bad news or 999999 to 1 bad news? The worst thing that can happen? 99999999999 to 1? Who knows? Complex science is weakest at these fringes exactly where traditional physics is strongest.

But we have good ways to think about the last percentile, or the last decile. The more extreme the outlier, the weaker our ammunition. To the most extreme question, the “worst case”, there is no really rigorous answer.

Regarding near term extinction, humans are now thriving in a way that no species known ever anywhere has previously. To suggest that a globally dominant population of seven billion specimens would go extinct in less than a generation is what, a 0.9999999 event? It seems more likely to be caused by a rogue asteroid than by anthropogenic climate change in any case. Right now, we have enough to worry about with the more-likely-than not scenarios, which really is Greg’s point.


  1. I don't think its great video; I think its terrible.

    Minorly, A / True doesn't have a happy face - it still has an appalling financial meltdown (in his scenario).

    But more importantly, he makes no attempt to assess the probability of B / True. So he's trying to short-circuit, or evade, the cost-benefit analysis that needs to be done.

    That wasn't the question you asked in this post, of course.

  2. I think there is a point to what you say. Consider, though, that the presenter is an American high school teacher. Accordingly, the level of confusion and denial he is dealing with is high and the sophistication is low. His first version of the video (prior to the space hamster version) was not successful. The point of the grid is of course that there is a credible threat. If the threat is not credible, obviously the argument fails. In a sense, inserting the credibility of the threat is indeed bringing risk into the question.

    I think the next step, a grid with more risk categories and more policy categories, is obvious enough as a question, and of course that is where the answer gets complicated. And that is why I'd like to get us past "global warming, yes or no", (and of course this is where we butt heads against your friends, the credentialed economists, for whom I can muster little respect). But insofar as the "global warming, yes or no" question goes, this presents a strong argument for people not in a position to evaluate the scientific debate for themselves.

    Of course, that wasn't the point I was making. Rather, I was explaining why, having made this argument, we still don't automatically know what to do. Which I think was your point as well.

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  4. "Spread the word" -- "And don't drink canned soda" (as in the backgroung of the video)


    Why would extinction be thinkable?

    1) Rapid population collapse due to population overshoot and resource depletion happens "every day" out there in the wild. Standard ecology. So it could happen to us, too.
    2a) The best chance for survivors would be migratory indigenous peoples who have not yet lost their skills to feed their own. E.g. in the Arctic or Papua New Guinea. (Sedentary farmers would be overun by the starving masses.)
    2b) The main amplificator/accelerator of human population collapse: Billions of individuals from collapsed civilizations suddenly finding themselves out in the wild, totally stupid and non-adapted, and the few skills and tools they have (warfare, chain saws) will just accelerate ecosystem collapse. That's why standard population overshoot/collapse is possibly to benign a scenario: In the case of the Late Homo S "Sapiens" it might be exacerbated by suigenocide.
    3) Main problems:
    a) Rapidity climate and ecosystem change: Indigenous survival skills might not adapt as rapid and be of no help.
    b) The rich: Might destroy and pollute everything (e.g. Canadian bitumen sand mining) in their desperate frenzy to first keep their toys running and finally get their stupid bellies filled.

    So, 2-3 generations would be my time estimate. Chances min. 1:999.

  5. I would say that given that humans are now thriving in a way that is unmatched by any other species may give us great cause for concern and may itself be evidence (which I believe it is) of our overshoot of Earth's resources. Unfortunately, our overshoot is global, so unlike the Easter Islanders, The Mayans, or other populations that were very successful just before their collapse, our collapse will be global, leaving very little for any pockets of humans that may be left. After all, the passenger pigeon was wildly successful just before it's collapse and extinction.

  6. It's not clear to me that the collapse of passenger pigeons is fully understood, although most of the blame clearly goes to humans, whether because of habitat destruction or direct hunting. In some ways, this makes the passenger pigeon a poor example, although even though we are not (for the most part) hunting ourselves we are certainly destroying our "habitat". Another interesting parallel is that there were so many passenger pigeons in the first place. Charles Mann, in the book "1491" raises the possibility that the abundance of both passenger pigeons and American Bison was a result of the collapse of Native Americans due to smallpox, leading to large scale ecological changes (since Native Americans were no longer managing forests/grasslands through burning). Whether or not this is indeed the case, our current population is the result of a similar situation, in our case medical and agricultural advances which have supported a tremendous growth in population, leaving us greatly overextended in a world which is becoming ecologically and climatically poorer. I would agree with Martin Gisser that nomadic indigenous people have the best chance of surviving but my fear is that climatic and environmental changes will render their skills ineffective. I would agree that extinction in a generation is pretty unlikely, but I fear that our extinction in the next four or five generations is a real possibility if we keep on the course we are currently on.

  7. Are you really sure mankind is safe from extinction? We are in a state of considerable population overshoot and nature always corrects overshoots.

    We are so dependent upon an economic industrial system that relies on perpetual growth in a very finite world. We hunt for food in supermarkets, we learn from a very complex internet web. Our society world wide is very complex, very stressed and highly interrelated. Catastrophic, cascading failure is not only possible but probable. When it happens it will be quick.

    On the other hand this inevitable failure could end up saving us as a species.

    So much of what we need to do to combat global warming is what we also need to do to prepare for collapse. The efforts to combat global warming will not be wasted.

    I actually think mankind will survive, but it will be a close call. For some the transition to a new paradigm will be relatively easy. But for the majority of survivors the transition will be horrendous. Six billion people entered the 21st century, I doubt any thing like a billion will enter the 22nd.

    Crunch the numbers on how much farmland will become useless, drowned, desertified or just so much less productive. Look at the rapidly disappearing ocean fish stock, even without climate change our oceans are in serious trouble.

    We are in very deep doo doo and we are not all going to get out.

  8. I found this prime time special from 2009 prescient, what might be expected from John Podesta. Unfortunately, he appears to have recused himself from the Keystone pipeline decision. It passed under the radar, which is very sad. It hypothesizes survival of a couple billion, which I think is about right. Main complaint was the "soviet-style" graphics. It was massively backed up with science.


    For those inclined to forget history, there was also a massive climate meeting at MIT in 2009, with most of the biggest administration stars. The whole thing imploded, largely thanks to the constant delay and blame game practiced by our political culture.

  9. (hope this can replace my comment with bad formatting)

    Re: "... suggest that a globally dominant population of seven billion specimens would go extinct in less than a generation is what, a 0.9999999 event?"

    Really? Hmmm, human "extinction" is that remote? It'is much more than quibbling over definitions to ask, How would we know? We couldn't, Since no one would be around to see it.... Instead, lets ask about half extinction... So I suggest we adopt the question of "when will peak population fall to half current numbers?" And that could be soon with known tipping points.

    In either definition of extinction, we could only know the horror of inevitability or high likelihood. We may already be there, but the timeline is off. But one generation? 25 years is quite possible: A major break at the Pine Island Glacier could blip sea levels very soon.

    Bacterial plagues could wipe out a huge segment of population - (I call that global warming related) For instance the WWI flu took out a significant fraction of world population in just a few years. If wildfires get much worse, there could be big problems. Are you saying that California droughts will suddenly ease up? Most Ag scientists predict global food stresses by the 2030s - If flowering plants cannot fertilize, then the famine stresses are not trivial It may not be a single "event" but the likelihood is far greater than your casual dismissal. this is all within the generation limit of 25 years.

    Calling the extinction in one generation a 7-nines event is not realistic. I can accept some other reasonable calculation... but that is not justified. It's easier to say that it's certainly not impossible. Maybe not likely. But it suggests other dates... end of the century is possible. End of 2 centuries hence more likely than not.

    There is plenty to discuss on this topic. It's not fair to casually dismiss it.

    He's a differently framed question: Will our planet have any humanoid life by the end of the next century?
    Call it 2199. What will be living here in 2199?

  10. Depends on what we do, of course. And that is the point. People who are adamant that it's too late, that the train has already left the station, that we needn't bother, are becoming a problem.

    We are active agents with something at least resembling free will. It is insane for us to try to predict what 2199 will look like.

    We should, rather, DECIDE what 2199 will look like. And then steer for that.

    As for the right number of nines, I will repeat my opinion, which is that science has no way to address that question.

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  12. I appreciate the guy's experiment. It is very much embedded in his North American (middle-class?) experience. Can we imagine this thought experiment being proposed by a slum-dweller in the periphery routing through garbage piles for sustenance? In that case, the False/B square is anything but a happy face. It's more despair: the future would be as miserable as the present. He asks us to imagine that (for that square) business as usual does not entail suffering. But it already does in the present. Would Bengalis working in sweatshops in buildings that will collapse on them or will burn to death because they are locked inside put on a happy face to see the system saved from "needless" regulations? For me, it's not because of climate change (catastrophic or not) that the imperialist/capitalist system should be rejected, but for more fundamental reasons. Climate change (certainly catastrophic sooner or later) is only more evidence that the system is fundamentally objectionable. Often these debates (like the one sparked by the entertaining high school teacher) require us to accept a spectrum of offensive assumptions. These are deeply embedded in any language that we can use to frame our arguments. That language has already been shaped by the ruling class and witlessly by many of their opponents. In fact, framing the debate like this allows the governing class to narrow all of the horrors of this system to the question of climate change. I know that is not the intention of this website.

  13. Rigor? In what sense is there rigor? It's the same 4-boxed argument, a facile one that you can apply to just about anything. Why you would want to characterize my pointing out the argument's history as a "grumble" I can't be sure, but, again, I don't see the point in inviting religious references when real science is available. And Craven, by his own admission, has not been an effective public advocate.

  14. Not discussing Greg here. This has been difficult for him but he certainly sells his own contribution short.

    If you fail to understand why the Newell/Smithson argument makes the point rigorous you are peddling the certainty or nothing nonsense and need to rethink how planning under uncertainty really works.

    Do you play poker?

  15. Mr. Tobis, that you disagree with my point does not require you to conclude that I'm peddling nonsense, though of course you may. I sincerely believe that invoking Pascal's Wager is an ineffective means to an end, where there are better alternatives.

  16. The "end" we are interested in here is to understand and address our risks and opportunities as a species on a planet whose fate we collectively control, and which provides us our sole means of support for the foreseeable future. I am not sure what ends you are interested in.

    Newell & Smithson have elaborated the appropriate risk management framework, which bears a resemblance to Pascal's wager but which nevertheless takes rigorous account of current understanding. Pascal, though a founder of probabilistic thinking, didn;t have a Bayesian framework to work with. We have the advantage over him.

    It is possibly appropriate for you, if you disagree with their probability assessments, to argue against those. But to dismiss the structure of the argument as equivalent to Pascal's wager is simply incorrect.

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  18. The wild cards of human ingenuity and phenotypic malleability make this more resemble Wascal's Wager, in which the wascally Bayesians point to Zeus and Odin waiting in the wings.

    Hard as Diamond touts existential threat inflation , not even the Easter Islanders managed extinction in situ, and the safest bet is that latter day Millerites, sacred and profane, will be coming down the mountain looking chagrined for many a Tuesday to come.

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