Climate impacts

Carbon brief has a very nice interactive report that show the impacts of climate change at 1.5C, 2C and beyond. It presents the various projected climatic, ecological, and economic changes on both global and regional scales. It is an impressive dive into the relevant literature.

On Twitter, Doug McNeall said something I’ve often wondered myself. Essentially, why don’t projections of large climatic and ecological changes lead to large projected economic damages? Of course, I don’t know the economic literature particularly well, so one potential answer is that some economic analyses do project large changes. However, it also seems that some certainly do not.

One possibility is that the global economic impact will indeed be relatively small, even if the climatic and ecological changes are large. Of course, even if this were the case, this wouldn’t necessarily imply that a cost-benefit analysis wouldn’t still suggest that it would be beneficial to address climate change.

Additionally, even if the global economic impact is relatively small, that doesn’t mean that there can’t be large impacts in some regions, or that some of the impacts (such as the loss of ecosystems, for example) aren’t things that are difficult to quantify economically, at least in a way that we would all broadly agree with.

However, I do think there are reasons to be cautious about some of these economic analyses. Let me provide a caveat up front. I’m not an expert at this, so am happy to be corrected if I get something wrong, and am partly writing this in the hope that I might learn something more.

For starters, these analyses are typically linear. This essentially means that they can say nothing about the possibility of some kind of large shock. Some of these analyses actually suggest the possibility of quite small global economic impacts even for extremely large changes in climate (see links below), which would seem to suggest that there is some point at which these calculations break down.

Also, as I understand it, most of these analyses do not consider how climate change might impact economic growth itself (see this Carbon Brief Explainer about IAMs). If the global economy grows at 3% per year, then it will be about 10 times bigger in 2100 than it is today. A large economic impact in 2100, might then seem small by comparison to the global economy at that time. Equivalently, if you discount these future economic costs to today, they can also seem quite small. Is it reasonable to assume that global economic growth will be largely unaffected by climate change?

My own view, which I’m happy to be convinced is wrong, is that these kind of analyses are fine if you want to understand things like what would happen if we did something (like impose a carbon tax). They’re probably also fine if you’re interested in how the economy will response to relatively small climate and ecological perturbations, or will respond over the next few decades. Where I think we should be more cautious is when the climate/ecological perturbations are large, or when considering very long, multi-decade timescales.

You might regard it as ironic that I’ve defended climate projections over quite long timescales, while suggesting that we should be cautious about economic projections over the same timescales. For starters, there are aspects of these climate projections about which we have more confidence than others (global versus regional responses, for example), and the uncertainty does grow as the timescale increases. So, it’s not as if we completely trust climate projections either. However, as this paper by Jonathan Koomey points out, physical systems have structural constancy, while economic and societal systems do not. We can be confident that the response of a physical system to a perturbation will be the same in the future as it is now. We can’t be similarly confident when it comes to economic/societal systems.

Hence, I think it is reasonable to be more confident in the long-term climate projections than in the long-term economic projections. However, I’m not suggesting that these economic projections have no value. As George Box said, all models are wrong but some are useful. I think it’s important to understand when we can be confident in what a model is suggesting, and when not. If some think we should be confident in economic projections over long timescales and even when the projected climate/ecological changes are very large, I’d be interested to hear why.

Links:
The impacts of climate change at 1.5C, 2C and beyond (Interactive Climate Brief post about climate impacts).
Q&A: How ‘integrated assessment models’ are used to study climate change (Carbon Brief post about Integrated Assessment Models – IAMs).
Economics and Values (Post I wrote about economics and values).
We don’t even agree about the basics (Post I wrote about why we shouldn’t judge climate models in the same way we might judge economic models).
The Treatment of Risk and Uncertainty in the US Social Cost of Carbon for Regulatory Impact Analysis (Paper highlighting: To take the DICE model as an example (Nordhaus, 2008; Nordhaus & Boyer, 2000), it can easily be shown that the assumption of a quadratic relationship between damages and temperature, together with the modellers’ specific coefficient values, implies that global warming can reach more than 6°C before the equivalent of 10% of global GDP is lost, and 18°C before the equivalent of 50% is lost.)

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57 Responses to Climate impacts

  1. verytallguy says:

    I’ve posted this before, but it remains relevant, I think:

    …integrated assessment models (IAMs) have flaws that make them close to useless as tools for policy analysis.

    http://www.nber.org/papers/w21097

    It’s well worth a read.

  2. vtg,
    I’d forgotten about that paper. Thanks.

  3. Ben McMillan says:

    I think the major thing that makes economic impacts so small even when large ecological impacts are seen is that IAMs don’t place much value, if any, on ecological services. In general, if it doesn’t appear as a line-item on a GDP statement, these economic models ignore it or treat it as of minimal value.

    There is some attempt to value how much people would care if key species went extinct but I vaguely remember the total value of the enjoyment of the ‘natural environment’ being around 200 dollars per person in the developed world. And fixed in real terms, so that it becomes dwarfed by the supposed rising incomes we will have over the next 80 years.

    For example: the biggest ‘money-value’ change in certain integrated assessment models is how much the costs of air-conditioning and heating change.

    Who cares if the oceans become anoxic and the Amazon dies out: I’ll save so much on my gas bill!

  4. izen says:

    There may be a deep underlying problem with economic modelling that extends beyond the specific deficiencies of IAMs. This paper, which examines why economic models failed to predict the 2007 crash, and may have misled policy by inherently excluding the possibility of any instability of the economic system, identifies a historical evolution within economics that placed mathematical formalism as more important than empirical analysis of real world processes.

    https://uhra.herts.ac.uk/bitstream/handle/2299/9136/904752.pdf
    ” As mathematics has swamped the curricula in leading universities and graduate schools, student economists have become neither equipped nor encouraged to prioritise real world economies and institutions. Treatment of big questions such as the nature and causes of the wealth and poverty of nations brings no accolade, unless one can reduce the analysis to a respectable formalism. ”

    This post risks ringing the bell of an economeretrician defending such mathematical formalism over the observed systemic behaviour of economies.
    It is rather like the Galactic electric current theories. Attractive because of their mathematical elegance and simplicity rather than any correspondence to actual physical processes.

  5. John Hartz says:

    ATTP: Thanks for promoting Carbon Brief’s new interactive tool. Your post could easily be transformed into a guest post on Skeptical Science. 🙂

  6. JH,
    It is a great tool. You’re welcome to repost it. Might be too much of my own ramblings, but if SkS is happy with that, that’s fine with me.

  7. John Hartz says:

    ATTP: I’ll run it up the SkS flagpole and see who salutes. 🙂

  8. Dave_Geologist says:

    a historical evolution within economics that placed mathematical formalism as more important than empirical analysis of real world processes

    That was the problem with the paper we discussed a few months ago which argued (in the main text) that we could delay climate action by taking advantage of natural CO2 drawdown. They used a closed-form solution that was elegant but overstated the rate of natural drawdown by an order of magnitude, so was completely irrelevant in the real world. IIRC they used an inelegant, non-closed-form numerical model in the supplementary online material, which did reasonably represent natural CO2 drawdown and invalidated the conclusions in the main paper. My reaction was: “what? put the realistic numerical one up-front and the elegant, simple one in the SOM, so people can play with it to get an understand of how tweaking parameters vary the results”.

    I couldn’t understand why the reviewers and editor didn’t have the same reaction. Maybe I do now. Shame that the rest of us have to live in the real world. That’s science for you. Always butting up against pesky facts.

  9. ecoquant says:

    I don’t know how IAMs work. It’s been mentioned about that they remain in linear regions, so either they avoid parts of the state space exhibiting bifurcations, or their operators don’t trust those parts because of lack of corroborating data. I cannot believe the claim — if it were made, I’ve heard it was — that IAMs or similar economic models lack instances of bifurcations in their equations. My reasoning on that is that if something as simple as Preditor-Prey-Grazing Resources has bifurcations, surely any realistic economic model must.

    My other reason for doubting these kinds of statements are the innumerable possibilities of sudden shifts from climate effects. An overtopped dam or leave isn’t a problem until it overtops, unless it crumbles. Large scale severing of supply chains, due to damage of transportation infrastructure, is not something which is quickly offset by a corresponding increase in prices. Blackjack players betting against the House in a fair game run out of resources and bust. These are all entirely reasonable structural changes.

  10. John Hartz says:

    ecoquant: Perhaps this article will advance your understanding of how IAMs work,,,

    How ‘integrated assessment models’ are used to study climate change by Simon Evans & Zeke Hausfather, Carbon Brief, Oct 2, 2018

  11. ecoquant says:

    Thanks, @John Hartz,

    I actually have read that article already. It’s not enough. I want to see that, and a detailed description of an IAM that’s taken seriously WITH it’s equations and THEIR description.

  12. Keith McClary says:

    “If the global economy grows at 3% per year, then it will be about 10 times bigger in 2100 than it is today.”
    Do these economic models say how many times as much material resources we will be extracting from lower grade ores from deeper holes? Those I have seen avoid this question by sticking in a magic unicorn “substitute product” deep in their equations.

  13. John Hartz says:

    equonant: Try Google Scholar

  14. John Hartz says:

    equonant: Did you check out all of the links embedded in the Carbon Brief article?

  15. ecoquant says:

    I have downloaded the doc for POLES-JRC and will have a look. Hopefully that’s representative.

    There was no Bibliography in the Carbon Brief article, although there is a link to a Wiki which offers documentation. I got POLES-JRC there.

  16. ecoquant says:

    We’ll, that was disappointing. It concerns emissions-energy tradeoffs, not climate harm, at least AFAICT. I also looked at the documentation of the NCAR PETS IAM piece in the Supplement at PNAS of O’Neill, et al. That simply assumes there are “dangerous clinate change” boundaries set exkgenously and sheds no light on the economic consequences of these being breached.

  17. Steven Mosher says:

    linear.. yes the damage to the economy from increases in the cost of energy might be non linear.

  18. Steven Mosher says:

    The Use and Misuse of Models for Climate Policy
    Robert S. Pindyck

    touches a bit on the functions under the hood.

  19. Steven,
    That’s what vtg highlighted in the first comment. It doesn’t present a positive picture of IAMs.

  20. John Hartz says:

    If IAMs have flaws that make them close to useless as tools for policy analysis what are the better alternatives? .

  21. John Hartz says:

    ATTP: A new website for you (and everyone else for that matter) to check out:

  22. John Hartz says:

    ATTP: A new website for you (and everyone else for that matter) to check out:

    http://www.climatepsychologyalliance.org/international/cpa-scotland

  23. ecoquant says:

    @John Hartz,

    If IAMs have flaws that make them close to useless as tools for policy analysis what are the better alternatives?

    Well, I haven’t look at your most recent link recommendations yet. (I am somewhat suspect because the ones from your first recommendations I looked at, admittedly with limit, ended up being flat tires.) However, you asked, and there are, for example, calculations of carrying capacity of the planet for humans. The population suggested by these is about a sixth of the present, with the gathering of resources and allocation to the actual being primarily because of use of fossil fuels. Now, admittedly this is a coarse number and estimate, but it suggests what the challenge for zero Carbon energy is if life and livelihood of humans at the present intensity is to continue.

    By any reasonable definition, that’s policy, whether or not it aligns with what are presently considered economic or political “realities” or powers. Obviously, you and anyone else can choose to disregard these recommendations. (And the ones, apparently, which were recently recommended from the scientific community.) I await action after the body counts in the United States get sufficiently large, and when people realize no other explanation is possible.

    Yeah, I might be dead before then.

    But, those who know this is going to happen are very likely to be better protected for themselves and those they love against its consequences. AFAIC, everyone else who doesn’t accept or doesn’t believe or, especially, obstructs, deserves what they are going to get. I care less about them by the day and, when I die, I just hope they get their comeuppance.

  24. izen says:

    @-ecoquant
    “there are, for example, calculations of carrying capacity of the planet for humans. The population suggested by these is about a sixth of the present…”

    I would be interested in the source(s) for this.
    One (fictional) speculation I have encountered had a stable population of several Trillion, admittedly with a significant amount of genetic modification of humans and a completely managed ecology.
    (T J Bass)

  25. verytallguy says:

    If IAMs have flaws that make them close to useless as tools for policy analysis what are the better alternatives? .

    Pindyck suggests what I would describe as a semi quantitative approach based on assessment of the likelihood of disastrous outcomes.

    I don’t know what the general economic literature says on this.

  26. verytallguy says:

    linear.. yes the damage to the economy from increases in the cost of energy might be non linear.

    There’s a catch-22 on this, though.

    If there’s though fossil fuel to keep the cost of energy low, climate change will fry us. If there isn’t, am energy price crunch will collapse the economy and starve us (actually, in the long term that every crunch is eventually inevitable unless our fossil fuel resources are essentially infinite).

    The only way out of this bind is to move rapidly to renewable energy and/or reduce consumption.

  27. Steven Mosher says:

    “Pindyck suggests what I would describe as a semi quantitative approach based on assessment of the likelihood of disastrous outcomes.”

    I would vote for his approach as an supplement to IAMS.

    There is some benefit in having simple transparent “models”.

  28. Steven Mosher says:

    “Steven,
    That’s what vtg highlighted in the first comment. It doesn’t present a positive picture of IAMs.”

    Ah sorry I missed that, i didnt click on his link.

  29. Dave_Geologist says:

    My reasoning on that is that if something as simple as Preditor-Prey-Grazing Resources has bifurcations, surely any realistic economic model must.

    My introduction to deterministic chaos was a model for the carrying capacity of a pond populated by large parents and small offspring, competing for the same food. For some parameter ranges, you had a stable population. For others, you had periodic oscillations between mostly-adults and mostly-offspring. And for others you had bifurcations and chaotic behaviour. I suspect you wouldn’t have got that without the fixed resources of a bounded pond, which is what drives the feedback between adult and offspring population sizes. So in addition to unrealistic, simplified maths, an assumption of unlimited resources/unlimited growth/unlimited currency/unlimited whatever perhaps contributes to the generation of stable linear or quadratic models.

    In an unrelated field, geothermometry, I was always sceptical about bands of oscillatory zoning in garnets being used to track temperature/pressure evolution. I could reproduce similar patterns by post-crystallisation diffusion in a simple quaternary regular solution. The excess free energy was linear in concentration and i-j interchange free energy (I had to get out my thesis to look this up 🙂 ), but when-you crunched the maths the activity coefficient for each component had quadratic terms in the concentrations of the other components and cross-multiplied terms in the concentrations of all components. That was enough to set up features analogous to Liesegang rings, at least for some parameter values.

    Climate economics ought to be ripe for bifurcations. For example it’s not a given that the cost of wind or solar electricity will fall below that for fossil fuels. There must be scenarios where it plateaus above or plateaus below, which evolve to very different outcomes in a regulation-free world. Likewise depletion of finite* resources like oil and gas or neodymium and lithium – when, where and who owns them.

    * Here I mean finite in the sense of economically extractable. There’s lots of oil and gas we could get out at a terrible EROEI, but you wouldn’t use it as an energy source. Lithium and the rare earths are actually rather common in the earth’s crust and I must have seen hundreds or thousands of monazite grains down a microscope. The problem is that they’re widely dispersed and rarely concentrated into economically workable deposits.

  30. Dave said:

    “In an unrelated field, geothermometry, I was always sceptical about bands of oscillatory zoning in garnets being used to track temperature/pressure evolution. I could reproduce similar patterns by post-crystallisation diffusion in a simple quaternary regular solution. The excess free energy was linear in concentration and i-j interchange free energy (I had to get out my thesis to look this up 🙂 ), but when-you crunched the maths the activity coefficient for each component had quadratic terms in the concentrations of the other components and cross-multiplied terms in the concentrations of all components. That was enough to set up features analogous to Liesegang rings, at least for some parameter values.”

    I really doubt that is deterministic chaos, Dave. These are temporal oscillations is a growing crystal, representing a high degree of ordering.

    In crystals, there is short-range order due to atomic and compound bonds, and there is long-range order due to collective interactions such as via the Ising model.

  31. ecoquant says:

    @izen,

    I won’t do the calculation here. Cohen, 1995 is one who has addressed the question squarely. There’s a lot been done since: Google Scholar says Cohen’s paper has 583 citations. I’ll end up at the bottom of the comment with a note on these discussions.

    The estimate comes from broad regressions of observed number of animals per area in ecosystems, not only humans. Ultimately, it’s a rule relating to animal mass in kilograms. That, in turn, is controlled principally by size of an animal, and the principal relevant control is power input in terms of consumed joules. Obviously there will be scatter depending upon activity of the animal and how it manages heat. That, in turn, depends upon mass per unit area.

    D’Arcy Thompson is credited with introducing a lot this thinking in the second chapter of On Growth and Form, but there’s been a good deal of work done recently.

    Critical to the question at hand are general rules for metabolic rate. The ratio of maximum metabolic rate to baseline is a think called metabolic scope and is about 10 for mammals, and, specifically, 20 for humans, 30 for dogs, and it is believed horses and pronghorns is about 50.

    A lot more of this is available in the late Steven Vogel’s Comparative Biomechanics: Life’s Physical World (2003, Princeton University Press).

    To arrive at a bound on any animal population size, it’s necessary to consider all the trophic relations needed to support life as practiced by the creature. These are generally some small multiple of the median energy input per individual. These are, in turn, convertible to resources available for harvesting to provide this energy. Carrying capacity is defined as the population density above which the growth rate of a consuming animal population becomes negative. That’s from Soetaert and Herman, A Practical Guide to Ecological Modelling, Springer, 2009, and its Chapter 2. (It has many references to carrying capacity, including discussions of differential equations relating these to other environmental variables, including bifurcations being discussed in its Chapter 7.)

    Now humans are big animals. Indeed, this one species consumes an enormous portion of Earth’s net primary productivity, estimated by Haberl, et al, 2007 at 24%. This is only possible because the species also consumes a great deal of fossil fuel energy which increases its ability to harvest resources manyfold compared to unpowered farming or growth. This energy per unit human biomass also provides comforts well beyond subsistence and these, in all likelihood, facilitate greater harvesting, including the ability to span wide regions looking for and obtaining additional resources, and kick-starting new technological developments.

    So the carrying capacity of Earth for humans is amplified because of its use of energy sources, primarily fossil fuels. Such carrying capacity could be maintained were these switched out for energy which had significantly less impacts, principally solar (and I include wind there). But, take away those energy sources without substitution, and the trophic constraints on existence are pretty severe, per, say, 14th century Europe.

    To calculate natural carrying capacity, you take median metabolic needs per individual, a natural resource density available, an range over which an individual needs to forage to obtain that energy per year (say), and then divide that into total amount of area having these resources.

    There is also a nice discussion of how carrying capacity and trophic requirements related to animal behavior in section 4.3 of Kokko’s Modelling for Field Biologists and Other Interesting People, Cambridge 2007.

  32. ecoquant says:

    Yeah, well, another way of looking at this switch-or-fry situation, given what I wrote to @izen above (once it comes out of moderation), is that Earth has a greatly expanded carrying capacity because of our present intensity of fossil fuel consumption. That’s a different kind of energy input, not one used to directly consume, but to facilitate whole species-scale harvesting. Alas it produces toxic byproducts. Carrying capacity can also shrink if the population density is so high, waste products aren’t readily removed.

  33. Dave_Geologist says:

    In crystals, there is short-range order due to atomic and compound bonds, and there is long-range order due to collective interactions such as via the Ising model.

    And solid solution, with migration of components. And multiple potential combinations of the four components with the same free energy. My point at the time was that internal zoning could be produced post-crystallisation (in the temperature window between crystallisation and effective closure of the system to diffusion, which might require a special cooling path but then this was a relatively uncommon phenomenon), as well as by temperature or pressure changes during growth. Your suggestion would also not require temperature or pressure changes during growth. PT changes were one potential explanation but not the only one, even though they tended to be treated as such

  34. verytallguy says:

    Indeed, this one species consumes an enormous portion of Earth’s net primary productivity, estimated by Haberl, et al, 2007 at 24%

    Whoa! That’s an incredible statistic!

    Does it include direct fossil fuel use or not?

    ie is it

    (fossil fuel + biomass consumed by humans s)/(total productivity) = 0.24

    Or some other metric? It just seems amazing.

  35. ecoquant says:

    That’s from PNAS … That’s of net primary productivity. See the paper.

  36. ecoquant says:

    Also, I should have probably qualified, that’s of terrestrial ecosystems, not ocean.

  37. verytallguy says:

    Ok, so terrestrial only, but not including fossil fuel use.

    Absolutely astonishing. I would never have guessed such an impact.

  38. Dave, Research I did from years ago on finding deterministic cyclic or ordered patterns in condensed matter growth were all performed under experimentally-controlled conditions. Nothing surprises me when it comes to combining elemental sources to create exotic compound crystalline structures.
    And that’s why it’s not surprising to me, or to the other former condensed matter physicists-turned-climate scientists such as Marston and Wettlaufer, that climate also shows these patterns. The conditions are controlled, but not by humans, so it’s more a matter of finding out what the controlling factors are.

  39. Important to recall, these are not validated models.

  40. @vtg,

    I remember the first time in my post-university random surveying of the current science when I stumbled on those HANPP (human appropriation of net primary productivity) stats and staring in disbelief. There is also the claim (reasonably well supported) that 97% of the total mass of land mammals is compromised of humans, their pets and their livestock. Or the similar claim (tougher to pin down) that 98% of the mass of all terrestrial vertebrates is comprised of humans, their pets and livestock. All head-turning factoids.

    And I don’t know why, exactly, but I remember being particularly bug-eyed when I read Klee and Graedel (2004) which indicates that of the 77 of the first 92 elements of the periodic table that they studied, humans were responsible for over 50% (often close to 100%) of the annual flow through the earth system, and responsible for between 15% and 50% of the annual flow of a further 12 elements. And, of course, that doesn’t even include Carbon, Nitrogen and Phosphorous, where we are still “only” responsible for roughly 9%, 7% and 6% of the annual flows, but because of the “stock” problems with their accumulation they all make the Planetary Boundaries list of looming problems.

    If one were not aware of the potential problems, we’d look like pretty damn impressive apes!

  41. I don’t find that 24% astonishing considering that fossil fuels are created from solar energy accumulated over a span of millions to 100’s of million years (i.e. ancient sunlight), only to be “squandered” by humans over the course of a couple hundred years. That’s quite am intense usage ratio.

  42. I remember seeing (Nobelist) Thom Schelling (at the Brookings Institute) riffing – supportively – on why the IAM’s tended to suggest that the economy would not be particularly affected by climate change.

    And if I recall correctly, his case largely came down to a claim that only a very few segments of the economy are directly impacted by rising temperatures – notably agriculture (specifically the farming component) and outdoor recreation, again, as I recall – and those in turn represent only about 4% of US GDP. So even if you lost all of the skiing, for instance, which is still a fraction of total outdoor recreation, the resorts would be repurposed for mountain biking, etc. and there would be an insignificant impact on total output.

    Further, even with agriculture, he seemed completely nonplussed by any impacts, asserting that we could just move crop production indoors, much as we had poultry production, football, etc.

    There didn’t seem to be any way to propagate damages further through the economy except via these narrow framings…

    I just mention this because, in addition to various of the criticisms by Pindyck and others, this always stuck with me… it is superficially appealing, by the way…

  43. ecoquant says:

    @rustneversleeps,

    … we’d look like pretty damn impressive apes!

    Virulent strains of viruses and other microbes are impressive, too … Until they kill off most of their hosts.

  44. Paul, the 25% human appropriation of net primary productivity does NOT include our combustion of fossil fuels. It is just – effectively – the amount to the annual terrestrial photosynthesis production of carbon that we use for food, feed, timber, clothing, fuel, etc.

    Fossil fuels are on TOP of that. I think they dwarf it, if I recall correctly…

  45. Ken Fabian says:

    I wouldn’t know how to calculate human contributions to Carbon fluxes except look at a diagram showing The Carbon Cycle and doing some adding and subtracting – but CO2 does appear to be humankind’s single most abundant waste product – by a very large margin. Yet I don’t think I’ve ever heard it described like that, even by activists.

    For a more average Australian than myself, I got a rough estimate of 6 times more CO2 than all other waste combined (17 metric tonnes vs 2.7 for all other waste). In keeping with counting the CO2 but not the total exhaust gases, I counted biosolids but not the total wastewater – wastewater being often considered our most abundant form of waste. At a global average of 5 tonnes per person it is still something like 80 times each person’s body weight every year, but for other ‘advanced’ nations it will be, like Australia, much worse than the global average .

  46. ecoquant says:

    @Ken Fabian,

    I once tentatively titled a climate education talk “On being Carbon Dioxide” (it got changed for me), because, from my perspective, our CO2 emissions are the greatest long-lasting legacy to Earth this civilization will have, far longer lasting than those of Ozymandias.

  47. John Hartz says:

    Speaking of climate impacts on humans…

    A landmark United Nations report revealed that catastrophic events induced by climate change could become regular occurrences as soon as 2040. In the report, published Monday, the UN’s Intergovernmental Panel on Climate Change predicts disastrous effects around the world if greenhouse gas emissions continue to increase at their current rate. Previously, scientists believed these severe consequences would happen if the planet warmed by 2 degrees Celsius; now, the threshold is only 1.5. Another related study, also published Monday, highlights the extreme toll climate change has already taken on the human psyche, 22 years before the 2040 warning.

    Short-term exposure to extreme weather, multi-year warming, and tropical cyclone exposure are all associated with worsened mental health, scientists affirm in the journal Proceedings of the National Academy of Sciences.

    “Our paper — when coupled with evidence that climate change may impact everyday human moods to severe outcomes like suicide — provides further evidence that exposure to heat, on average, worsens mental health outcomes,” study co-author and MIT Media Lab research scientist Nick Obradovich, Ph.D., tells Inverse. Obradovich and his colleagues reached this conclusion by analyzing the mental health data of nearly 2 million Americans, as well as daily meteorological and climatic data taken between 2002 and 2012.

    “If we push global temperature rise into the 2 degrees-plus Celsius range, the impacts on human well-being, including mental health, may be catastrophic,” he says.

    – Sarah Sloat, Inverse, Oct 8, 2018

    https://www.inverse.com/article/49698-climate-change-negative-mental-health?utm_campaign=science-innovation-2018-10-08&utm_medium=inverse&utm_source=newsletter

  48. Marco says:

    Since Nordhaus has been mentioned…he just got the Nobel prize in economics:
    https://www.nobelprize.org/prizes/economics/2018/nordhaus/facts/

  49. Marco,
    Yes, I saw that, and specifically for his work on climate change.

  50. Dave_Geologist says:

    our CO2 emissions are the greatest long-lasting legacy to Earth this civilization will have, far longer lasting than those of Ozymandias.

    Slightly more subtly, ecoquant, it will be the C13 perturbation caused by that organic CO2 as it gets sequestered in sediments, shells etc. That will still be detectable billions of years after the CO2 and climate have returned to normal.

  51. Marco says:

    Also fun, in the Netherlands a(n appeal) court case of a citizen-organisation against the Dutch state was won by the former, meaning the court has ordered the Dutch government to keep its promise of reducing CO2 emissions by 25% by 2020:
    http://www.climatechangenews.com/2018/10/09/dutch-court-shoots-government-appeal-landmark-climate-ruling/

  52. Turbulent Eddie says:
    “Important to recall, these are not validated models.”

    Who is supposed to do the validation? The Supreme Court?

    Are these the same people that invalidate models?

  53. John Hartz says:

    Paul: The only way to “validate” the models is to power up a time machine and travel to the year 2100. Perhaps TE could stowaway. 🙂

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