Climate change doesn’t work like that

A couple of years ago I wrote a post where I tried to explain why I thought climate change was a different kind of problem when compared to most of the other issues we might face today. I find it a tricky argument to make, because I don’t want to suggest that the other problems we face don’t matter, or that there aren’t consequences to not addressing them now, but the essential irreversibility of climate change does make it a somewhat unique issue.

I noticed that Jonathan Gilligan had highlighted a quote on Twitter, from Jody Freeman, that – I think – neatly summarised the point

You can put rules back in place that clean up the air and water. But climate change doesn’t work like that.

Yes, in many situations, if we were to implement processes to address our impact, then we can reverse that damage that’s been done. Climate change doesn’t really work like that. A significant fraction of the CO2 we’ve emitted will remain in the atmosphere for a very long time.

Credit: Tierney et al. 2020

This is illustrated by a figure from a very nice paper on how [p]ast climates inform our future, by Jessica Tierney and colleagues. The figure shows past, and potential future, atmospheric CO2 concentrations. The key thing is the x-axis, which shows a period of over 600000 years. On our current trajectory, atmospheric CO2 will remain above 400ppm for thousands of years, and won’t return to pre-industrial levels for 100s of thousands of years.

Additionally, we’ve already increased atmospheric CO2 to levels comparable to that of the Pliocene (a few million years ago) and could increase it to levels not seen for 10s of millions of years.

What I’m getting at is that what we’re doing is unprecedented and has extremely long-term consequences. This isn’t to say that we should ignore everything else and only think about addressing climate change. I do think, though, that it’s worth being aware of how climate change is likely different to the other kind of problems we may face and should bear that in mind when thinking about how to work towards a better future for all.

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69 Responses to Climate change doesn’t work like that

  1. Tony B says:

    I wonder what atmospheric CO2 concentration allows the natural glacial cycles to return. They apparently involve a CO2 drawdown.

  2. This paper suggests we’ve already delayed the next glacial period by about 50000 years, and will probably delay it by at least 100000 years if we keep going as we are.

  3. David B Benson says:

    Tony B — This won’t directly answer your question, but is certainly related reading:

    So: to reinitiate the large glacial cycles appears to require a carbon dioxide concentration of less than 280 ppm.

  4. Eventual_Horizon says:

    In the words of Frodo Baggins, “How do you go on… when in your heart you begin to understand… there is no going back? There are some things that time cannot mend… some hurts that go too deep… that have taken hold.”

    The lag in climate response to emissions is another one of society’s blind spots when it comes to its perception of climate change. We think going carbon neutral — unachievable on a multi-decadal scale — means we will have “won.” But if emissions were to cease tomorrow what sort of freeze cycle would we end up with as far as Arctic sea ice goes? How many months a year would be ice free and what sort of chaos would that wreak on the jet stream and global weather patterns?

    If emissions were to cease tomorrow what would be the true rebound in temperatures from the loss of anthropogenic aerosols? 0.5C? 1C? More?

  5. David,
    As I understand the paper that I highlighted in my earlier comment, there is a relationship between atmospheric CO2 and solar insolation at 65N that determines if we move into another glacial period. For atmospheric CO2 concentrations above 280ppm, it requires really low levels of insolation at 65N. I think it’s possible to move into a glacial period at atmospheric CO2 levels above 280ppm, but the conditions are rarely satisified.

  6. Despite some history on the other side of RCPx.x and “2100” arguments, I think it is worth noting here that Tierney et al.’s figure above runs up to 2000 ppm atmospheric CO₂.

    That’s roughly 12x as much as we’ve currently added ((2000-415)/(415-280)). Which (as I know you are aware) requires prodigious emissions from oil and natural gas relative to reserves *and* a sharp reversal in coal trends and/or *very* large contributions from carbon feedbacks.

    None of which counters the very important point about effective irreversibility. But I think the plot itself needs to be understood against those parameters.

    I have always remembered something that Myles Allen said in 2009, discussing Jim Hansen’s 2008 “Target Atmospheric CO₂” paper. In that paper, Hansen argued that the full Earth System Sensitivity (ESS, slow feedback) is closer to 6°C, so we should actually aim for 350ppm (we were at about 385 ppm in 2008) to hold warming to ~2°C. But as Allen points out, Hansen’s 6°C ESS requires you to first climb well above 3°C and then stay there (or above) for centuries in order to get doubled CO₂ (560ppm) to have any hope of continuing to warm to 6°C.

    And Myles Allen’s point was, given that we were (are) trying to stay *well* below a doubling of CO₂ (about 450 ppm per the Paris <<2°C goals), does it really germane if the ESS is 6°C?

    And I get a similar vibe looking at a plot exploring 2000ppm. It's interesting and important, but it doesn't seem policy or motivationally relevant. And I think I am quasi-reconciling myself to the earlier defence of RCP8.5 in the scenario set because the naysayers truncated the exploration at 2100/~800ppm. Here we get the full monty of the scenario all the way to 2000pm.

  7. Rust,
    Yes, I think Myles Allen’s point is a good one. I also agree that the RCP8.5 concentrations in that figure are likely to be unrealistic. But even RCP4.5 stays above 400ppm for ~thousand years, and doesn’t return to pre-industrial for ~100000 years.

  8. David B Benson says:

    aTTP — I fear that you read too much into but one of the papers Ganapolski has co-authored on this subject.

    Most importantly, there is a correlation between isolation @ 65 °N and the onset and subsequent termination of major glacial periods. Causation remains to be determined.

    Grossly, the carbon dioxide concentration in the atmosphere controls the global climate, although not independent of the positions of continents, major mountain ranges, etc. As a show-off, the GISS crew ran their climate model without any atmospheric CO2; the globe promptly froze in but a few modeled weeks.

    As best as can be determined, interglacials end when atmospheric CO2 concentrations fall well below 280 ppm, for whatever reason.

  9. David,
    I think my description of the paper I highlighted is roughly correct. I didn’t say it was right :-). I agree, though, that it seems likely that going into a glacial period when atmospheric CO2 drops below ~280 ppm.

  10. Mitch says:

    We should also be aware that we are loading up the ocean heat reservoir as we raise the global temperature. Pushing heat into the ocean lowers the surface temperature change, but if it goes on long enough there is a reservoir of heat that can be re-emitted during a cold transient.

    Pliocene and earlier climates worked from a large heat reservoir that made it more difficult for the earth to cool. We are building that heat reservoir relatively quickly over the next few hundred years.

  11. Ben McMillan says:

    Slightly at a tangent to the OP, but I’m wondering how plausible it is to think that humans will really let the climate sit at 3C above pre-industrial for millennia. Apart from anything else, you would be in continuous retreat from the shoreline at a rate well over 1m per century. Clearly, based on what we’ve done to date, we are pretty stupid, but are we really that stupid?

    I think it is likely, in the long term, that we will be able to ‘reverse’ climate change; even if it is expensive and difficult. That is, even if negative emissions technologies aren’t as effective as some of the IAMs assume, they could still probably pull temperatures back to pre-industrial over a couple of centuries.

    But you can’t bring back the species and ecosystems that get damaged in the meantime. You also can’t undo the human suffering associated with climate disruption. Those kinds of damage are the really irreversible bit.

  12. David B Benson says:

    Ben McMillan — For example, plant oh-so-many trees:
    offers a variety of links on that topic.

  13. Ben,
    I agree that if we get to something like 3C, we may then start investing in ways to reverse some of that change. Of course, some types of geo-engineering carries risks, but we may well find ways to capture and store CO2. One thing I’m not sure about is how easy it would be to reverse ice sheet melt, given that if the height of the top of the ice sheet has dropped, then it would be exposed to warmer temperatures even if we could reverse overall global warming. Some sea level rise may be baked in whatever we do.

  14. Ben McMillan says:

    On that note, people are putting blankets on glaciers to try to stop them melting:

    More seriously, I guess the question is how many cryosphere tipping points we will have already triggered by 2050. Hopefully Antarctica and Greenland react slowly enough that they can be put back to sleep.

    This is partly why I think people might eventually go for direct radiation management to manage temperature; it might be better than living in a climate that is very far from equilibrium for a significant length of time.

    DBB: The take I heard on the trillions of trees thing was that even if you believed the authors’ calculations it would only be good to reduce CO2 levels 10 percent or so, and implementation would anyway be problematic for various reasons.

  15. Bob Loblaw says:

    If we get to something like 3C, who thinks we’ll still have a functional civilization with the resources available (money, skills, etc.) to be able to invest in massive geo-engineering at a scale sufficient to change things back?

  16. David B Benson says:

    Ben McMillan — I recommend reading the serious links that I supplied above. Ignore the street talk that you have ‘heard’.

    In any case, tree planting is not considered to be a total solution by itself.

  17. David B Benson says:

    aTTP — Actually reversing ice sheet loss would require initiating a glacial stade for some centuries. Possible in principle.

  18. Not-in-my-name says:

    [But ABC. -W ]

  19. Ben McMillan says:

    DBB: this comment on the paper suggests the trillion-trees-thing would be good for reversing 5% of emissions-to-date.

  20. Chubbs says:

    We don’t have a clear vision of the solutions either. Key non-fossil technologies are all progressing much faster than anticipated. Myopia that we haven’t been pushing them harder.

  21. Mal Adapted says:


    We don’t have a clear vision of the solutions either. Key non-fossil technologies are all progressing much faster than anticipated. Myopia that we haven’t been pushing them harder.

    And as we all know, we haven’t been pushing carbon-neutral energy production harder because the marginal climate-change costs of fossil fuels are still held external to their market price: IOW, we socialize our private costs simply because we can. “Myopia”, individual and collective, is as good a word as any for the root of all tragedies of the commons. Far too many of us can’t see the big picture, especially if it’s more than a couple of years away.

    AFAICT, the tragedy of the climate commons is in both the classical Greek sense, of humans powerless against the inexorable workings of the universe; and in the aggregate grief and misery the victims of AGW suffer, often far out of proportion to their individual contributions to the problem 8^(.

  22. ” One thing I’m not sure about is how easy it would be to reverse ice sheet melt, given that if the height of the top of the ice sheet has dropped, then it would be exposed to warmer temperatures even if we could reverse overall global warming. ”

    Point well taken, but it has a bizarre geophysical corollary: isostatic rebound of the bedrock beneath the ice. Much of the Greenland cap ice is a kilometer thicker than its surface elevation- the accumulation weight has, over eons, created depressions deeper than the Dead Sea basin.

  23. Clive Best says:

    Delaying the next ice age by about 50000 years is not necessarily a bad thing.

  24. David B Benson says:

    Clive Best — 50 kyr already done. Much, much longer possible:

  25. Willard says:

    > Delaying the next ice age by about 50000 years is not necessarily a bad thing.

    Is it contingently a good thing tho.

  26. Clive Best says:

    There is a philosophical question. Has human development been a bad thing? Probably it has been for the rest of nature. However our time horizon is just 3 or 4 generations so ~ 150 years.

  27. mrkenfabian says:

    I consider the lifetimes of people now living – ~100 years, not far short of Clive’s 150 years – as the time horizon of greatest importance. Not just the circumstances expected during that time period but what the conditions will be at the end. Which blurs the boundary.

    What happens in 50,000-100,000 years is irrelevant and I don’t know that good vs bad can be a valid metric that far out. Better that the people living in the time of an approaching glacial maximum decide what they deem good or bad and what actions they ought to take rather than for us to take that decision from them.

  28. Joshua says:

    > Has human development been a bad thing? Probably it has been for the rest of nature. However our time horizon is just 3 or 4 generations so ~ 150 years.

    Some people argue that human development has been bad for humans. Perhaps a naturalistic fallacy, but there are some reasonable arguments. Healthy diet. Lots of exercise. Fair amount of leisure. Egalitarian communities. No war to speak of. No billionaires. No attacking people for their views on climate change.

  29. Willard says:

    > There is a philosophical question.

    Many ill-posed questions look philosophical. Witness “what’s the meaning of a word”? As JL once remarked (DOI:10.1093/019283021X.003.0003):

    Now if we pause even for a moment to reflect, this is a perfectly absurd question to be trying to ask. I can only answer a question of the form ‘What is the meaning of “x”?’ if “x” is some particular word you are asking about. This supposed general question is really just a spurious question of a type which commonly arises in philosophy.

    If, as AT suggests, what we’re doing is unprecedented and has extremely long-term consequences, there’s little to be gained in trying to wonder what ifs in the end we lived in the best possible world. The relevant question should contain what ifs we don’t.

  30. Ben McMillan says:

    Although looking mostly at the next 100 years or so makes some sense, now we have the power to cause very long-term impacts, we need to take on the responsibility for them.

    Mass-extinction, and the impoverishment of ecosystems, are arguably worse crimes against posterity than even a hundred millennia of disrupted climate. But the shorter term damage to human civilisation is also worth mentioning…

  31. Dave_Geologist says:

    Clive, absent clear-air capture we’ve already cancelled the next Ice Age, which is indeed a good thing (for humans).

    But now we’ve achieved that it no longer exists as an excuse or counter-balance for emitting more CO2 and doing more damage than was needed for that cancellation.

    There’s also the not insignificant fact that the damage will be in the coming decades and centuries. You’d have thought people would be more concerned about that than about something tens of thousands of years into the future, but maybe I’m missing something.

  32. Ben McMillan says:

    The odd thing is that the IPCC scenarios are effectively banking on indirect air-capture of CO2 to get to 1.5C:

    Partly because even slamming on the brakes on emissions as hard as possible it still takes a few decades to get near zero. Also, a substantial fraction of residual emissions ends up in the too-hard-basket and need to be compensated for forever.

    But burning a lot of forests and burying the resulting CO2 (BECCS) looks problematic on a big scale for various reasons.

  33. Chubbs says:

    “has human development been a bad thing?”

    I don’t understand the question. Fossil fuel technology is outdated and losing ground vs newer technologies. Human progress in the energy sphere is overdue.

  34. Dave_Geologist says:

    No war to speak of Joshua, but you were more likely to die a violent death at the hands of another human.

    Did Warfare Among Ancestral Hunter-Gatherers Affect the Evolution of Human Social Behaviors?

    The mortality data summarized in Table 1 are consistent with what is known about the Late Pleistocene from more indirect data. Frequent lethal intergroup encounters may reconcile two otherwise anomalous facts about hunter-gatherer demographics. Human population grew extraordinarily slowly or not at all for the 100,000 years prior to 20,000 years before the present (35, 36), yet under peaceful conditions foraging populations are capable of growth rates exceeding 2% per annum (37, 38).

    If you fancy a long read: Violence and Warfare among Hunter-Gatherers.

    And if you’re interested in genetic determinism: The phylogenetic roots of human lethal violence. But we (and bonobos) are exceptions which prove (or disprove) the rule.

    The phylogenetic analysis suggests that a certain level of lethal violence in humans arises from the occupation of a position within a particularly violent mammalian clade [primates], in which violence seems to have been ancestrally present. …

    This prehistoric level of lethal violence has not remained invariant but has changed as our history has progressed, mostly associated with changes in the socio-political organization of human populations. This suggests that culture can modulate the phylogenetically inherited lethal violence in humans.

    Non-phylogenetic factors include things like territoriality (for obvious reasons) and sociality (loners can’t afford to get injured, let alone killed, because they’d starve; groups will generally establish an internal pecking order).

    The first and third could be taken as showing that it’s not just cats and dogs that domesticated themselves 😉 .

    The no-war claim usually ignores the evidence, or defines war in such a way that hunter-gatherer tribes can’t meet the definition due to their small numbers and multi-tasking. But you’re just as dead if you’re killed in a tribal conflict over territory or resources or by someone counting coup or in a long-running blood feud, as you are if you’re killed by a uniformed soldier in a standing army.

  35. Joshua says:

    Dave –

    Thanks. I’ll take a look. I wasn’t really making an argument so much as suggesting tacit assumptions are sub-optimal.

  36. Clive Best says:

    Fossil fuels are only outdated compared to nuclear energy.

    Renewable energy was outdated by fossil fuels already in 1750.

  37. Ben McMillan says:

    Well, if all you care about is total amount of forest in the world, that hasn’t changed that much recently.

    Forests are not that strong a lever on global CO2, but are incredibly important and often irreplaceable ecosystems. They provide essential ecosystem services, to the people that live in and near them, and it matters a great deal which forests are growing and shrinking. Compare something like the Amazon to a Northern Europe pine plantation. Part of the controversy with the trillion-trees-thing is that taking a place that has always been grassland and covering it with trees is not necessarily a win in ecological or even CO2 terms.

    So I guess I see forest protection and reestablishment as a crucial task from an ecological point of view, and a little bit of CO2 sequestration is just a nice side benefit.

    Electric vehicles are a bit like this too: by far the biggest benefit is to human health, although the CO2 reduction is substantial.

  38. Chubbs says:

    OK Clive, will give fossil fuels the 19’th and 20’th centuries. However even the BP energy outlook doesn’t give them the 21st. The BP BAU case has fossil fuels losing significant market share to renewables by 2050. With a harder push, i.e. properly pricing in climate damage, FF decline rapidly.

  39. Willard says:

    > Renewable energy was outdated by fossil fuels already in 1750.

    I doubt there were enough kites back then to create the proof of concept for a power plant, Clive.

    Quick question:

  40. Joshua says:

    Willis Eschenbach is admired by more than just a couple of online “skeptics” for his approach to presenting evidence.

    Well, here we go…

    > So I would consider 0.085% of the population dying to be a hard upper limit on what the disease does when you do nothing. No country to date has gotten there, and there is no sign that any country will get there after the virus subsides.

    Now I tried to tell Willis, as the time, that he was underestimating the impact of uncertainty…but he didn’t want to listen.

    For the US, if we project from current numbers who have already died from COVID and add a projection of those that are currently infected and are likely to die… (let’s say 300k total)… we will likely be at 0.09% at a minimum.

    Belgium is already at 0.14%

    And BTW, here’s what Nic Lewis said at the time…

    > the convergence in your graph of lines approaching the 0.085% of population deaths level is certainly suggestive of somewhere near that being a possible upper limit.

  41. Joshua says:

    It seems that Nic Lewis must be in a witness protection program.

  42. Eric Winsberg posted a video with what seemed like a plausible criticism of the Flaxman paper. My own take is that it is tricky to know if we could have limited the spread without going into a full lockdown and I can certainly understand how we get to a point where we not willing to take that risk.

  43. David B Benson says:

    An unsophisticated summary of CCS:
    Summarizers oft fail to appreciate that burning of so-called fossil fuels must stop.

  44. Joshua says:

    Anders –

    > My own take is that it is tricky to know if we could have limited the spread without going into a full lockdown.

    Are you basing this on a particular herd immunity threshold and no vaccine?

    Presumably, if an effective vaccine gets distributed and interventions short of a “full lockdown” (which, imo, is an ambiguous term) can delay infections if not prevent them from occurring eventually, then calculations would have to change, no?

  45. Joshua,
    What I mean could we have avoided a full lockdown if, for example, we’d been willing to work from home if possible, socially distance, wear masks, etc. So, I’m not arguing against interventions, just suggesting that we can’t rule out that we might have been able to implement interventions that could have limited the spread without a full lockdown. Having said that, once we’re on the exponential rise phase, then it becomes very risky to try implementing something short of a lockdown because if it doesn’t work, then things very quickly get our of control.

    I guess, the argument made in that video seems to be that some of the interventions in place before the lockdown was implemented in the UK, may have already been bringing the R number. However, if this is people deciding to work from home, not go out, etc, then it may be that this wasn’t sustainable without something pretty definitive from the government to say that you have to keep doing this.

    Certainly a vaccine does increase – IMO – the case for continued interventions, because we would now be in a situation where we can avoid some of the possible futures deaths, which may not be the case if a vaccine were not likely to become available.

  46. Joshua says:

    Anders –

    All makes sense to me.

    > this wasn’t sustainable without something pretty definitive from the government to say

    Here we had extended unemployment compensation, loans made available, stimulus, etc. All of which helped people to stay at home. Unlikely they would have been made available absent the shelter in place orders. But sure, it’s theoretically possible that if we’d had an actually functioning federal government that cared about anything other than Trump’s chances of reelection, more sensible poliies could have been implemented.

  47. Clive & Willard should cut Ben Franklin some slack–
    20 megajoule lightning bolts may not add up to a lot of kilowatt hours per kite, but his stove reduced fuel consumption for wood and coal alike .

    Joshua should rejoice that Red Team Trump has but two months left to run:

  48. “Having said that, once we’re on the exponential rise phase … ”

    What so-called “exponential rise phase” anyways?

    Because, I have not seen such from the get go …

    A horizontal line, or constant, is so-called exponential growth on a doubling time series. Note that the 7-day reweighing algorithm is taken at the daily confirmed/deaths stage (just in case some think that I am smoothing the doubling time plot itself, as that is not what I am doing). There are places where re-zeroing stuff on either axis will give you gigo, of course. The best place to see that is in the EU time series, where the dailies reached minima sometime last summer, re-zero time, deaths and confirmed thereabouts and voila so-called exponential growth phase. I can show a graph of that, play around with the accumulation time series start times and jack the y-axis somewhat. :/

  49. “Certainly a vaccine does increase – IMO – the case for continued interventions, because we would now be in a situation where we can avoid some of the possible futures deaths, which may not be the case if a vaccine were not likely to become available.”

    Actually, it is pretty obvious that the health systems are improving, both regionally and globally, temporally speaking. Thus, interventions from cradle to grave, regardless of vaccine availability, work better over time. Either that or the age fatality distribution is so skewed that we killed off the most susceptible earlier then we are now. In any case, there are lessons that are being learned over time, that make the pay me now or pay me later assumption, rather bogus to begin with in the 1st place.

  50. mrkenfabian says:

    The renewable energy options of 1750 may have been largely made obsolete by fossil fuels but the far more extensive and impressive renewable energy options of today are making thermal coal obsolete and are gaining ground on gas and oil.

    One side of politics promoting solar and wind as empty gesture politics and the other as give em enough rope politics has been the best thing to happen to climate… politics; even long running power companies that initially mocked and resisted renewables are now big investors and the alarmist fear of economic loss and ruination from pursuing emissions reductions, that had been the most influential argument by business lobbies against enacting climate policies, is losing it’s power to dissuade governments to act.

  51. Ben McMillan says:

    Note that UK hospitals now have about the same number of covid patients as in the peak in Spring. So there was definitely not much wriggle room.

    I’d be a lot more impressed with the anti-lockdown people if they weren’t consistently contrarian about anything that helps their argument, or if they actually promoted stronger interventions to reduce the need for lockdowns.

  52. Dave_Geologist says:

    You’d have thought a regular commentator on science, and especially someone who had a scientific education and used to be a science journalist/writer, would know the difference between a prediction and a projection (in this context).

    In the case of the IPCC quote it’s both, because the thing it’s conditional on is included in the sentence. Asking whether it was a right or wrong conditional prediction is an ill-posed question. You have to go back to the models and see what conditions were assumed, in particular what future emissions growth. You’d also have thought a science writer would know what an ill-posed question is and avoid asking or answering them.

  53. “Climate change doesn’t work like that”

    So how does it work?

    “It was part wonder and part responsibility,” he says. “This thing was coming and it would disrupt lives and economies across the planet, and I realized I might be the only one on Earth who knew it.” – David Pierce, Scripps Institution of Oceanography

  54. Chebyshev says:

    I am not sure it is a unique problem.

    Person X is poor. Grows up eating what is classified as “junk” food because that is what cents can buy. Certainly not organic. Lectures about potential harms of nasty pesticides and harmones are irrelevant to him because there is a more binding constraint.

    Of course, there is a bunch of nutritionists with PhDs, who project that if X continues as he does, he will be dead soon of heart attack or cancer. Some “experts” also project that there is a point of no return and that eating healthy after decades of abuse will not help. At some point the whole discussion degenerates into an intellectual debate among the credentialed on the irreversibility of certain paths (of eating) and twitter is dominated by the circle jerk. X is still poor and needs to eat to stay alive and does not care.

  55. Dave_Geologist says:

    But does X need to over-eat? Certainly not to stay alive.

    That’s what leads to most health problems, not what you eat.

    And soon only in the sense that several decades is soon. IOW in the sense that the Earth is flat.

  56. Ben McMillan says:

    I’m sure there must be a food-based analogy to resistance to dealing with climate change:
    “It’s all just small hands banging down on a small table, as they refuse to eat their broccoli.”

    But climate change doesn’t work that way, because the consequences largely fall on someone else.

    Think it is more like children thoughtlessly or willfully discarding their snack packaging. If littering had fatal consequences. Social pressure, it needs to be applied.

  57. Chebyshev does illustrate an issue I do have with this narrative that I’m promoting. Of course there will be examples of situations where we can pass some point where an individual, or some group of individuals, might experience something that will have some impact that we cannot reverse. However, collectively, this is less common. We can do things to reverse poverty, poor healthcare, some environmental impacts. It’s true, of course, that delays in doing so may have an irreversible impact on some. Climate change is somewhat different in that the global changes are essentially irreversible on human timescales. However, as William Connolley has pointed out (and as I often do highlight) we could develop technologies that would artificially draw down atmospheric CO2 and would, hence, reverse the changes we’ve induced. So, you could argue that it’s not technically true for climate change either. However, we have not yet developed such technologies, or implemented them at scale, so it is likely that it would be better to avoid getting to the point where we might want to do so (my view, of course).

  58. Ben McMillan says:

    Although I think that carbon-removal methods and other more brutal forms or climate-change reversal might actually be useful even at this point, they are clearly inferior alternatives to preventing emissions in the first place. And it seems a bit pointless having a discussion about how to reverse climate change until we’ve stopped making it worse.

    Also, even if you can fix global temperature, the ecosystem/biodiversity damage is really irreversible on human timescales… you can’t fix extinct. People being forced to move off islands is pretty permanent too; if it comes back out of the waves a century or two later, it won’t ever be the same place.

  59. izen says:

    “But does X need to over-eat? Certainly not to stay alive.
    That’s what leads to most health problems, not what you eat.”

    Under-nutrition is a greater problem than over-eating globally.
    But even the over-eating is often a result of poverty in the ‘richer’ nations due to the availability of cheap refined carbs being available and cheaper than a good balanced diet.

    All of this is the result of economic interests in the food production systems.

    Likewise the economic interests in fossil fuel use dominates the global energy sector and defines what people can do. Although as ATTP points out the effects are persistent and largely irreversible without a massive effort to recapture CO2

    It is the economic interests that need to be modified on a global scale to change the health of people and the planet.
    Tinkering with individual choice is suboptimal.

  60. Joshua says:

    I think the problem with Chebyshev’s analogy is that it doesn’t account for the political overlay that interacts with how people orient around the issue of climate change. It isn’t merely a matter of how people rationally decide what’s in their best interests or how people make choices so as to most efficiently meet their needs and balance their needs against the long-term cost/benefit analysis for society.

    This is like the “rational actor” and “maximizing utility” problems with economic theory. Those models are useful but clearly insufficient for describing human behavior.

    Analogies are useful for instructive purposes, and it’s a mistake, imo, to merely criticize them for having practical limitations. But…on the other hand… I think the limitations of that model ARE important to consider.

  61. mrkenfabian says:

    Some form of negative emissions is needed in order that emissions requirements not prevent our freedom of choice to indulge in high emissions activities; if you really want to keep driving a fuel guzzling, high emissions relic, sure you can, but you have to pay for the negative emissions. It is only when everyone’s lifestyle choices, even the extravagantly wealthy and wasteful ones, are zero emissions that we will achieve zero emissions.

  62. David B Benson says:

    Testing links:
    — where just the most recent entry was desired.

    Still, it is all relevant.

  63. Ben McMillan says:

    If we were struggling to survive, we wouldn’t be causing much of a carbon pollution problem, so I don’t think the claim that we are all too poor to do anything about climate holds water. Indeed there are many poor people, but they are largely not the ones causing the problem.

    The problem of taking action is more along the lines of:

    That is, people think they are going to lose out, relative to others, due to policies that advance sustainability. This is about positional status within countries, who can claim to be moral and right, and who feels like their livelihoods and way of life will be threatened.

  64. David B Benson says:

    Need to hurry up and be about it:
    In particular, see the last link, to the UN Environment Programme article.

  65. Ben McMillan says:

    I don’t think net-zero is really the goal: the goal is to avoid damage. And sitting at 1.5C, or 2C, above preindustrial roughly implies a time-constant level of damage. So a better long-term goal would be to take things back to preindustrial.

    Maybe a bit colder to put the big glaciers back to sleep.

    Ultimately, if you think 1.5C is dramatically better than 2C, then maybe we should be aiming lower.

    There has been a bit of a resurgence in discussion of NETs:

  66. Pingback: 2020: A year in review | …and Then There's Physics

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