RealClimate logo

4th National Climate Assessment report

Filed under: — gavin @ 23 November 2018

In possibly the biggest “Friday night news dump” in climate report history, the long awaited 4th National Climate Assessment (#NCA4) was released today (roughly two weeks earlier than everyone had been expecting).

The summaries and FAQ (pdf) are good, and the ClimateNexus briefing is worth reading too. The basic picture is utterly unsurprising, but the real interest in the NCA is the detailed work on vulnerabilities and sectorial impacts in 10 specific regions of the US. The writing teams for those sections include a whole raft of scientists and local stakeholders and so if you think climate reports are the same old, same old, it’s where you should go to read things you might not have seen before.

Obviously, since the report was only released at 2pm today without any serious embargo, most takes you will read today or tomorrow will be pretty superficial, but there should be more considered discussions over the next few days. Feel free to ask specific questions or bring up topics below.

103 Responses to “4th National Climate Assessment report”

  1. 51
    Ron R. says:

    Nigel, #32. Having some form of tax incentive might help, and I think better education on the benefits of smaller families would go a long way and costs little.

    Here here!

    Al Bundy, #41. I just read that water report you linked to. Did you happen to catch that last statement:

    Finally, state and federal regulators must make tough decisions about how and when to allocate water to the environment during a drought. They are faced with balancing short-term economic impacts on urban and agricultural water users against long-term harm—even risk of extinction—to fish and wildlife.

    People are making a distinction between urban and rural use of water, as if only one of those is human population related. Maybe a relatively few farmers are using more water than the population at large, but they are using it to grow crops for that very population. If those people were growing those crops themselves then it’d be obvious they were using that water. If, theoretically, there were a lot less people, there wouldn’t need to be so much agriculture, land or water. So combine the urban and agricultural to get a more accurate picture of water use by the population. Again, one species is appropriating the resources that are needed by all. Not because it’s right, but because they can

    This from the LA Times article, “Trump orders quicker environmental review of California water projects”

    Trump then handed the pen to Nunes, who for years has introduced legislation attacking the federal Endangered Species Act. Several of his proposals have passed the House only to die in the Senate.

    “This will move things along at a record clip,” Trump told the group. “And you’ll have a lot of water. I hope you’ll enjoy the water you’ll have.”

    Btw, I agree wholeheartedly on your almond comment. Throw alfalfa into that water wastage complaint too. Horses should not even eat it. It may look like grass, but it’s actually a legume that’s bad for them. My horse’s (when I had her) moon blindness cleared right up when I took her off of it.

  2. 52
    Chris says:

    U.S. negotiators blocked progress at the Group of 20 summit on managing migration, slowing climate change..

  3. 53
    MA Rodger says:

    Karsten V. Johansen @42,
    It is true that global primary energy use is rising, although not at the 3%pa stated in the Broecker quote @38. It has been averaging 1.5% over recent years.

    Yet your comment @42 that ” the amount of non-fossil energy used is still absurdly low. Most of it is still burning of wood in mostly very poor countries, ie burning down rainforests etc.” is contradicting the numbers I set out @38. Of the 15% of primary energy provided by non-fossil fuels, the numbers @38 show only 3.5% is not hydro or nuclear. And digging into those numbers further, of that 3.5%, the majority is solar and wind, with 16% biofuel and 24% geothermal/biomass. So “most of it” is certainly not “burning of wood” and also I would suggest not in “very poor countries.”

    A further point that may penetrate the gloom, 60% of this rapidly growing “other renewables” delivers electricity which is poorly compared with fossil fuel primary power data. In UK and likely elsewhere the fossil fuel used to generate electricity is perhaps three-times the energy of the electricity. Thus, where it is competing in traditonal elecricity useages, the 3.5% of “other renewables” is equivalent to 8% of primary fossil fuel use. So it is not as “absurdly low” as you would imagine – and not forgetting the significant year-on-year growth.

  4. 54
    zebra says:

    #45 Kevin McKinney,

    I don’t know how accurate this is, but it offers a start on quantification rather than handwaving:

    You say:

    So we need to support efforts to bring down birthrates, especially where they remain very high.

    But population is a very difficult variable to manipulate in the real world, except by massive increases in death rates. To put it bluntly, population can’t be reduced quickly enough to solve the climate crisis,

    Apparently, we don’t really need “massive increases in death rates” at all. Plug in a fertility of 1.5, and a period of 100 years, for example.

    Also, “where they remain very high” is probably not as big a problem as where they are closer to the replacement number, like India– as you point out, it isn’t necessary for massive economic (consumption) increases to drive reductions in fertility.

    Of course, if “solving the climate crisis” means a Nirvana-like magical elimination of all the negative effects, which at this point almost nobody thinks is possible, perhaps you are correct.

    But if we look at a realistic timeline, and recognize how reducing population growth acts synergistically with an energy transition, it makes sense to greatly increase resources devoted to that goal.

  5. 55

    I expressed some doubt about your proposal to “pay women not to have children”…

    Right, or at least, me, too. After all, there are already serious intrinsic disincentives to undergoing childbirth, such as a high probability of prolonged inconvenience during pregnancy, of serious discomfort during childbirth, and not inconsiderable medical risk during both, up to and including the risk of death.

    As in Gertrude Stein’s quip about authorship–“I enjoy having written“–it’s to a considerable extent a case of the end justifying the unpleasant means.

    Which is why, when women have 1) the power to choose with relative freedom, 2) reasonable assurance that the children they already have will probably survive to adulthood, and 3) life choices beyond or in addition to motherhood that are worthy of their talents, they tend to limit family size.

    The conclusion I draw is that these conditions should be supported and encouraged worldwide, and particularly where they do not yet generally apply. It would also be prudent to continue to support relevant research to ensure that these conditions are not only necessary, but also sufficient.

    There is, of course, the possibility of removing or limiting extant subsidization of childbearing and/or rearing. Here’s the view from the other side of the looking glass, as it were:

  6. 56
    Matthew R Marler says:

    It’s only available for download in parts. Does someone have a nifty R or SAS program for downloading the whole thing?

  7. 57
    David Young says:

    Kevin, @35, It’s pretty well impossible to predict economic circumstances 80 years in the future because the system is adaptive to changing circumstances. I question why the report tries to do so given the huge uncertainties. This is of course why it is overly pessimistic to talk about 15 degree increases as well. That would require at a TCR of 2 about 2240 PPM of CO2. That I think is not going to happen. I doubt we can get even within a factor of 3 of that.

    There is a post up on the RSS website about their temperature datasets compared to CMIP5. In the tropics the models are running about a factor of 2 in anomaly than the data. For the globe, its more like 1.5. I don’t think there is any longer any doubt that climate models are predicting too much warming particularly in the tropics and that there is something wrong with the modeling of convection/clouds.

  8. 58
    Ron R. says:

    Kevin McKinney, #55.
    Here’s the view from the other side of the looking glass, as it were:

    “as my late friend Julian Simon was fond of remarking, human beings are the ultimate resource, the one resource that we cannot do without”.

    Hmm, kind of says it all about the guy’s pov. No need for nature to escape from the rat race in. Low priority on any natural resource not connected to profit. Clean water, fresh air, healthy food, he could take it or leave it. A very harsh and austere outlook.

    I prefer the words of Thomas Berry:

    What happens to the outer world happens to the inner world. If the outer world is diminished in its grandeur then the emotional, imaginative, intellectual, and spiritual life of the human is diminished or extinguished. Without the soaring birds, the great forests, the sounds and coloration of the insects, the free-flowing streams, the flowering fields, the sight of the clouds by day and the stars at night, we become impoverished in all that makes us human.


    Time and space – time to be alone, space to move about – these may well become the great scarcities of tomorrow. ~ Edwin Way Teale

  9. 59
    Ron R. says:

    Anthony Barnosky. Stanford University Executive Director of Jasper Ridge Biological Preserve and Professor of Biology. Emeritus Professor of Integrative Biology at UC-Berkeley.

    Short video:

    Short video from the Center for Biological Diversity:

    “Human Population Growth and Wildlife Extinction on a #CrowdedPlanet”

    A simple explanation from the EPA (somehow missed by Trump).

    Population/Extinction Graph:

    People believe that first world countries like to United States have their acts together, yet there are a lot of population and development related threatened and endangered species here as well.

    Again, overpopulation is related to every serious environmental ill we are suffering, including climate change. Let’s pull out heads out of the sand and address it.

  10. 60
    dhogaza says:

    RSS says the following about the discrepancies noted by David Young. Of course, he doesn’t note that “observational error” is likely to be a contributor to the discrepancy, along with possible modeling issues. Nor does he mention that the discrepancy can mostly be explained without resorting to model physics errors and that his claim that “I don’t think there is any longer any doubt that … there is something wrong with the modeling of convection/clouds”, which would fall under model physics errors, certainly isn’t what RSS is stating.

    ‘Why does this discrepancy exist and what does it mean? One possible explanation is an error in the fundamental physics used by the climate models. In addition to this possibility, there are at least three other plausible explanations for the warming rate differences. There are errors in the forcings used as input to the model simulations (these include forcings due to anthropogenic gases and aerosols, volcanic aerosols, solar input, and changes in ozone), errors in the satellite observations (partially addressed by the use of the uncertainty ensemble), and sequences of internal climate variability in the simulations that are difference from what occurred in the real world. We call to these four explanations “model physics errors”, “model input errors”, “observational errors”, and “different variability sequences”. They are not mutually exclusive. In fact, there is hard scientific evidence that all four of these factors contribute to the discrepancy, and that most of it can be explained without resorting to model physics errors.’

  11. 61
    Ron R. says:

    Mr. KIA, #44. Sorry, missed this: You cannot simply toss out beliefs of others just because you want to – they have rights too, correct?

    Can you think of anything we’ve tossed out before because it was destructive? Anything harmful that was previously entrenched in society for hundreds or thousands of years? I’ll name a few. Slavery, the subjugation of women, whaling, blood letting, religion in public schools, female circumcision (oh wait, that’s still occurring. In fact in some corner of the world most of these things are still occurring) etc. etc. You get the point. But civilized society has mostly done away with these things. And each began with education. Certainly, everyone has an absolute right to their own beliefs. But they are, and should be, constrained in their exercise when they are shown to be harmful to others or the environment. No one’s perfect, and one hopes allowance is always made for that where the repercussions are minimal.

    For those who complain that I have not come up with adequate solutions. Here’s what I came up with so far:

    1. We need a big national and international informational push, from heads of state on down, like we did and continue to do with CC, addressing population, explaining where we’re headed if we do nothing.

    2. listen to what people, especially biologists, are saying, what conclusions they are reaching after all this discussion. Then implement the best ideas.

    3. Personally, I like the idea of paying women not to procreate. This can come happen in various ways, either by direct payment with the money paid by destructive interests, say dirty energy or the military, which in the US receives around $1,000,000,000,000 a year (come on, do we really need new bombers and bombs every single year?) We already do this with the tobacco companies. Or we can do it in a way that would be more acceptable to Republicans as nigel suggests in 32 with tax cuts.

    4. Encourage western families [those most responsible for rampant consumption] to stay together if possible, like they do in Asian countries like Japan where space is at a premium. The point being to reduce construction of new homes and all the stuff that people need to fill them with.

    5. Restructure the economy around deconstruction, i.e. actually tearing down and recycling buildings, cities etc.

    6. Use AI to help figure these tough, thorny issues

    Maybe these things are naive but they’re starter ideas.

    To these I’ll add the comments of the American Institute of Biological Sciences (I’m only including those directly related to population here):

    We are jeopardizing our future by not reining in our intense but geographically and demographically uneven material consumption and by not perceiving continued rapid population growth as a primary driver behind many ecological and even societal threats (Crist et al. 2017). By failing to adequately limit population growth, reassess the role of an economy rooted in growth, reduce greenhouse gases, incentivize renewable energy, protect habitat, restore ecosystems, curb pollution, halt defaunation, and constrain invasive alien species, humanity is not taking the urgent steps needed to safeguard our imperilled biosphere….Sustainability transitions come about in diverse ways, and all require civil-society pressure and evidence-based advocacy, political leadership, and a solid understanding of policy instruments, markets, and other drivers….further reducing fertility rates by ensuring that women and men have access to education and voluntary family-planning services, especially where such resources are still lacking….estimating a scientifically defensible, sustainable human population size for the long term while rallying nations and leaders to support that vital goal.

    They end by saying:

    Soon it will be too late to shift course away from our failing trajectory, and time is running out. We must recognize, in our day-to-day lives and in our governing institutions, that Earth with all its life is our only home.

  12. 62
    gkoehler says:

    RE #44 Mr. KIA

    The reality of climate change crisis is no longer arguable any more than gravity or biological evolution. The science is overwhelming. Intelligent educated persons who willingly dismiss life threatening risks for short term personal gain are indeed depraved. Krugman was right.

    I do agree that the media have not done a good job of laying out the case and mechanisms vs. focusing on tragedy of the day. ‘If it bleeds it leads”. But some media outlets are trying, esp. PBS.
    And websites like Skeptical Science provive comprehensive coverage. RealClimate is great but too technical for many people.

    As for Trump being evil. While name calling is not a productive course, in this case evil needs to be named for what it is. Mr Trump is a self-serving liar. He lies routinely, or as the bible says of Satan, when he lies he is speaking his native language. Millions, more likely billions, of human lives are at stake and be blows off recent climate change warnings because he doesn’t “believe”. He doesn’t even read the full reports. It doesn’t matter what he believes. He is is responsible to project lives and instead is chasing an insatiable need for power and dollars. I’m fiscally conservative. What does spending two Trillion on a tax cut primarily for the wealthy without even a pretense that trickle down effects will cover the reduction in treasury receipts. We just borrowed it from our kids with no intention to ever pay it back ourselves. I agree with borer security, but not using false fears of the other to whip up xenophobia. Trump is not a conservative. He is a demagague manipulating conservative political affiliations to serve his own hungers. Williman Buckely must be rolling in his grave. I pity Trump’s unfillable psychological needs, but I want him out of office to minimize the harm he is causing.

  13. 63
    David Young says:

    Well, dhogaza, There is indeed a lot of grasping here in terms of explaining the discrepancy, much like that involving the tropospheric hot spot. However, what they and you failed to mention is that convection is an ill-posed problem and one of Isaac Held’s interesting posts was about aggregation at which models fail because of extremely coarse resolution. So it is quite unlikely that convection models are very accurate just based on a priori mathematical knowledge. Nor is it likely that the lapse rate theory which is an adiabatic theory is very accurate either.

    The fact of the matter is that in the tropics, it appears to me that MRSS data shows roughly half the warming rate of the CMIP5 models. I doubt that can be explained away as due to “observational errors” or “internal variability sequences” since its a 40 year trend we are looking at. In fact, MRSS recently changed their data processing method and that brings their warming rates into better agreement with HADCRUT for example, which has been very well vetted over the last 30 years.

  14. 64
    Ron R. says:

    Ok, I just thought of a solution that is both gross and deeply disturbing, but just might work. Plus it would please those who would see technology as the savior of the world: The sex robot, or sexbot. “Male” and “female”. Built with recycled materials.

    Google it.

    (My apologies to evolution)

  15. 65

    Re #23, 37, 35, 57, 58 & 63–

    One could choose to try to diagnose climate sensitivity from the observation/model mismatch in tropospheric warming rates.

    It would be a bit fraught, of course, because there are, as the RSS site points out, and Dhogaza brought into this discussion, large uncertainties associated with the observational data, as well as questions with forcings, etc.

    Or one could look at the totality of research on TCR/ECS. “One” wouldn’t have to, though, because it has conveniently been done already:

    ECS is likely in the range 1.5°C to 4.5°C with high confidence, extremely unlikely less than 1°C (high confidence) and very unlikely greater than 6°C (medium confidence). The transient climate response (TCR) is likely in the range 1°C to 2.5ºC and extremely unlikely greater than 3°C, based on observed climate change and climate models.

    So I would gently suggest that speaking as if a TCR of 2 is some sort of limit to the “attainable” is premature, at best.

    And while we’re looking at the ‘convenient’, while AR5 Ch. 12 does not give CO2 concentrations for the various scenarios (a little ironically preferring instead radiative forcing), Table 12.3 tells us that 62% of the RCP 8.5 model runs actually resulted in a global temperature increase of at least 4 C.

    (FWIW, Wikipedia gives an RCP 8.5 CO2e concentration in 2100 of just under 1250, which leads me to wonder why David Young quotes a number northwards of 2200 as ‘necessary’–I wouldn’t think, OTOH, that his TCR of 2 accounts for all the discrepancy.)

    Recapping my calculation above, 4 C equates to 7.2 F, which doubled to account for the land vs. ocean issue becomes 14.4 F. Even before correcting for latitudinal and other climatic factors which would push the number higher, I think that indicates that the NCA estimate of 15 F is not unreasonable on the face of it.

    David says “It’s pretty well impossible to predict economic circumstances 80 years in the future because the system is adaptive to changing circumstances…”

    I’d reply that that is not actually a counterargument to what I said, which is in essence that things could get a lot worse than a 10% hit to GDP. David hints at optimism when he continues “because the system is adaptive to changing circumstances…” Presumably he means the economic system here, and of course it is true that humans will try with great ingenuity and persistence to make the best of things as they are. However, the presumption of neoclassical economic theory that natural capital can be always be replaced by human-created capital has been demonstrated repeatedly, since the 1980s, to be simply wrong. (Eg., the work of Herman Daly.) And natural ‘adaptation’ is not necessarily “good” in human terms. (Eg., the rise of antibiotic resistant infections). So I would also suggest that the downside risk remains unconstrained.

    David declined to supply any support to his contention that RCP 8.5 is “probably unattainable”, forcing me to go looking to see whether there was anything to that or not. I found that there is this:

    Says that:

    Climate projections calculated in this paper indicate that the future atmospheric CO2 concentration will not exceed 610 ppm in this century; and that the increase in global surface temperature will be lower than 2.6 °C compared to pre-industrial level…

    Well, that is great news, if correct, but that’s just one study result, after all. And while I called it “great news” in the last sentence, it’s still not what one would call a “great outcome,” given that that would still breach the 2 C guardrail by a considerable margin.

    I would also note, FWIW, that this study has not exactly taken the research world by storm, racking up 11 citations in a year or so.

    I did some additional searching to investigate what current work says about RCPS, but the concentration of the two studies I looked at was on the lower end–i.e., the question of whether there’s a realistic chance of avoiding 2 C. (Spoiler alert: short version, probably not.) So, depressing if unsurprising as that result was, it didn’t help me with the upper end of the spectrum, particularly since both were paywalled:

    And by the venerable William Nordhaus:

    So, looking at the lower bound, 2.6 C (the number from David’s source) equates to ~4.7 F, which doubles to 9.4 F for land. Not a cheerful prospect.

  16. 66
    dhogaza says:

    David Young:

    “Well, dhogaza, There is indeed a lot of grasping here in terms of explaining the discrepancy, much like that involving the tropospheric hot spot. However, what they and you failed to mention…”

    Well, it’s your source, which you referenced as though it supports your own beliefs. I simply pointed out that your reference doesn’t say what you implied it says. In particular failing to mention that RSS themselves believe that observational error plays a role is, well, not exactly honest of you, given what RSS does for a living …

  17. 67
    dhogaza says:

    David Young:

    “The fact of the matter is that in the tropics, it appears to me that MRSS data shows roughly half the warming rate of the CMIP5 models. I doubt that can be explained away as due to “observational errors” or “internal variability sequences” since its a 40 year trend we are looking at”

    Take it up with RSS, since you quote them as your authority.

  18. 68
    Matthew R Marler says:

    60, dhogaza, quotes: They are not mutually exclusive. In fact, there is hard scientific evidence that all four of these factors contribute to the discrepancy, and that most of it can be explained without resorting to model physics errors.

    So the models are inaccurate and physics errors is only one of the possible explanations. Surely possession of accurate models would be an improvement over this state of affairs. I for one am optimistic that accurate models will be developed. In the mean time, the models are inaccurate; is that not so?

  19. 69
    patrick says:

    @58 Ron R.: Thank you very much. I identify with the remarks of T. Berry and E. W. Teale which you cite. A recent survey that found many Americans go to their cars to have a private space where they can get-away-from-it-all, as I recall.

    “The impoverishment of nature is the impoverishment of the imagination.” T. Berry said this too. It’s like a short form of the quote you cited.

    “The Insect Apocalypse is Here” (The NYT Magazine, Brooke Jarvis, Nov 27) is the best thing on the extinctions–at any level–that I’ve seen. It tells a great secondary story about amateur contributions to observational science that are so good they’re professional–kind of.

    Human intellectual and imaginative life are joint casualties of the degradation and extinction of the diversity of life and habitat, per the quote you cite–because degradation and extinction necessarily shift the focus from primary and fundamental phenomena to severe pathological states. If for no other reason.

    “A 1995 study, by Peter H. Kahn and Batya Friedman, of the way some children in Houston experienced pollution summed up our blindness this way: ‘With each generation, the amount of environmental degradation increases, but each generation takes that amount as the norm.’ In decades of photos of fishermen holding up their catch in the Florida Keys, the marine biologist Loren McClenachan found a perfect illustration of this phenomenon, which is often called ‘shifting baseline syndrome.’ The fish got smaller and smaller, to the point where the prize catches were dwarfed by fish that in years past were piled up and ignored. But the smiles on the fishermen’s faces stayed the same size. The world never feels fallen, because we grow accustomed to the fall.” (see article)

    Never send to know for whom the bell tolls.

  20. 70
    David Young says:

    Dhogaza, I referenced the RSS graph and then gave my opinion of what the data implies. Putting words in my mouth is not very honest. You are avoiding the real issue here which is not about appeals to authority.

    To repeat for your benefit. I gave you some first principles reasons supporting my opinion. There is a rather striking inconsistency in the tropics. “Internal variability” a concept that is pretty ill defined is in my opinion not a very likely explanation over a 40 year time period. Likewise, measurement errors are of course always present, but RSS’s latest version is in pretty good agreement with HADCRUT, which is well fitted. More likely is that convection and cloud models are inaccurate just as turbulence models are inaccurate in some cases very inaccurate.

  21. 71
    zebra says:

    #65 Kevin McKinney,

    Just to clarify for those who didn’t look at it, your reference that proposes a limit on temperature seems to be based on a “peak oil” analysis rather than questioning the models themselves.

    I was hoping that you will respond to my #54 over on FR. It would be nice to deal with actual numbers, and that calculator I found does the trick. Also it would be nice if we could get the topics on topic, and have the people here discussing population move there.

  22. 72
    zebra says:

    #70 David Young,

    It would be helpful if you could elaborate a bit on “the real issue”. The RSS quote says “most” of the discrepancy could be explained without questioning model physics.

    OK, arguendo, I stipulate that there is some equation somewhere in the model that causes some part of the difference from the data. You suggest it is an inaccuracy associated with clouds, or convection, or turbulence. Well, OK, but…so what?

    I don’t know if others are “putting words in your mouth”; my problem is not enough words coming out. What can we conclude– of any significance– based on your hypothesis?

    If I had the models and the computing power, I would tweak some of those parts you suggest and see which direction the variable in question goes. Then I would look at (possibly) changed other variables in the system, and how they agree with the data, after those tweaks. Very basic.

    Are you suggesting that there would be no funding for such an effort if it was likely to lead to some revelation– again, of any significance– about the effects of CO2 on the climate?

  23. 73

    MRM, #68–

    In the mean time, the models are inaccurate; is that not so?

    So tempting to respond with the classic Flannery O’Connor cheap shot to the effect that “You are correct; that is not so.”

    But I’ll be good and say instead that an “accurate/inaccurate” mutually exclusive binary is not a useful formulation. Must we really quote George Box again, for the zillionth time?

    I guess so:

    All models are wrong but some are useful.

    Climate models are imperfect, but have demonstrated skill, and are improving all the time. If you want perfect ones, though, you need to investigate some other, alternate, universe–as Box pointed out.

  24. 74
    Ron R. says:

    Patrick, #69, exactly. Old people forget what used to be while young people never knew. The change is so slow it’s insidious. Still, some of us remember.

    Another quote:

    “There is a pleasure in the pathless woods,
    There is a rapture on the lonely shore,
    There is society, where none intrudes,
    By the deep Sea, and music in its roar:
    I love not Man the less, but Nature more,”

    George Gordon Byron, 1788 – 1824

    A good video if you can get it.

    Will read the NYT article.

  25. 75

    Ron R., #58–

    I hope it was sufficiently clear from the Alice reference that I don’t share the perspective of the fellow I cited, but rather provided it as both a contrasting ‘light’ on the issue, and as a data point in and of itself.

    If not–and really regardless of whether, I suppose–let me say that I, too, appreciate the quotes you responded with.

  26. 76
    PattiMichelle says:

    Where is the discussion of Carbon Budgets, in order to align with the massive conversation with the 2018 IPCC Special Report, etc.?

  27. 77
    Wookey says:

    Ron. You do not seem to be aware of the work of the gapminder institute which has excellent tools and data on population:

    It is instructive to take their ‘chimpanzee test’ population quiz to check your assumptions.

    I agree that population is a massive problem, which makes most of the other problems much worse, but the point is that it is already under control in most of the world. The number of children born worldwide (136 million) has barely changed in 4 years – essentially the base population finally stopped rising (obviously overall population will still rise significantly because those new people last ~70 years).$chart-type=popbyage

    It’s simply not true that ‘developing countries in Asia’ have high fertility rates. Most of them are already low. Bangladesh, Bhutan, Thailand, Malaysia, Indonesia, China are all well below replacement, and Laos, Cambodia, Myanmar are only just above and still dropping. Thailand and China have rates well below the US and most of Europe. Only Pakistan, Yemen, Iraq, Afghanistan, Philippines, Tajikistan, Jordan, PNG and Palestine remain above 3.

    Only sub-Saharan Africa still has high fertility rates, and they are dropping there too since the 70s and 80s. Nigeria is the biggest problem as it’s big _and_ high birthrate. It’s currently projected to be a 400m population country by the time it stabilises.$state$time$value=2018;&marker$axis_x$which=children_per_woman_total_fertility&domainMin:null&domainMax:null&zoomedMin:null&zoomedMax:null&scaleType=linear&spaceRef:null;;;&chart-type=bubbles

    The point of all this is that the population problem is actually largely fixed, assuming we can keep current trends in place. Fertility rates are already below replacement in most of the world, and we are already on track for a stable population around 2070. There isn’t much that can be done to bend the curve very far there – people last a long time… The thing we _can_ change quickly, if we put our minds to it is the other half of the problem: consumption, which is why it makes sense to concentrate efforts there, whilst not taking our eye off the development/contraception/healthcare ball in the developing world. It is possible for countries to regress, see Egypt 2006, Tunisia 2005, France 1997, USA 1977 (and 2002), but it’s quite rare.

  28. 78
    Ron R. says:

    Kevin McKinney, #75. Thanks. No worries, I didn’t think you shared the site’s perspective.

  29. 79
    Matthew R Marler says:

    73, Kevin McKinney, quoting Box: All models are wrong but some are useful.

    Box also wrote that it is a problem to determine how inaccurate a model can be and still be useful.

    Only “some” are useful, as you and I and Box agree. It is not so that every wrong model is useful.

  30. 80
    Ron R. says:

    Wookey, I’ve responded on the Forced Variations thread.

  31. 81
    zebra says:

    #77 Wookey,

    I replied to your comment on the Forced Responses thread, which is where the moderators would like us to discuss mitigation and politics and so on, keeping the other threads more on topic.

    I look forward to your response.

  32. 82

    zebra, #70–

    Just to clarify for those who didn’t look at it, your reference that proposes a limit on temperature seems to be based on a “peak oil” analysis rather than questioning the models themselves.

    Correct. I was inquiring whether there was anything in the literature to support David Young’s bare assertion that RCP 8.5 was “probably unattainable”, and a little time with Google Scholar turned up that particular study. The point had nothing to do with climate models; rather the study used *economic* modeling to demonstrate that less fossil fuel would/will be used than had been believed or assumed.

    Of course, it’s just one study, and it’s quite new, so it doesn’t support the implication–and DY didn’t actually say this, though the tone of his comments seems to me to imply it–that NCA 4 was somehow remiss in considering the RCP 8.5 scenario. And I wouldn’t want to bet our world’s future on any one study, particularly when, as I understand it, our current FF use most resembles RCP 8.5.

    One may, of course, hope–and I think there is some reason for it, given the cost-based tipping-points in the energy economy we’re seeing globally. But it’s still sort of a glimmer at this point, IMO.

    Turning to your comments about population, I did see your #54 on FV, and I did play with the calculator a bit. (Surprising to me: the highest TFR for which I could get a stable population, eventually, was ~1.74; that makes no sense to me, so there must be something I don’t understand–perhaps I need to check the TFR definition. I’d thought that that number should be slightly over 2.)

    But I have a couple of questions. First, what, specifically, do you want to know in terms of a discussion with ‘real numbers?’ And why not pose it yourself using the calculator, rather than pointing me to it and hoping for the best? I’m game, but I’m not sure where you want to go.

    And why is this thread better for population discussions that FV–isn’t managing population in fact mitigation? And given that this thread is about a US report, and population is a global issue, maybe FV would be better? (Not that it matters; clearly we’re talking about it here regardless!)

  33. 83

    #77, Wookey–

    Yes. Thanks for saying very well what I had previously tried to convey.

  34. 84

    On the population calculator zebra pointed to, it’s here:

    And I figured out the problem I was having with TFR–I was overlooking the existence of an immigration parameter. (Makes sense for national/regional populations, but for global population, not so much.) Zeroing it out brings replacement level to 2 exactly, which I think is slightly over-idealized:

    If there were no mortality in the female population from birth to the end of the childbearing years, the replacement level of TFR would be very close to 2.0. The replacement fertility rate is indeed only slightly above 2.0 births per woman for most industrialized countries (2.075 in the UK, for example), but ranges from 2.5 to 3.3 in developing countries because of higher mortality rates, especially child mortality. The global average for the replacement total fertility rate (leading to a stable global population) was 2.33 children per woman in 2003.

    (Note here that the 2010-2015 global TFR is given in the same source as 2.36–though to be sure, mortality has probably dropped since 2003, too. But it does dramatize that at the global level we’re surprisingly close to replacement level TFR.)

    A somewhat confusingly-worded but useful discussion from good ol’ Wikipedia (and the source of the quote above):

    Returning to the calculator, I found that you can type in values to the various parameters by clicking on them; you don’t have to use the sliders, which are annoying if you want precision–and you might, because it’s *awfully* sensitive to the exact TFR value–and which limit the possibilities.

    As a leading instance, you can type in negative values to the immigration parameter, which lets you investigate the effects of out-migration on global population, should, e.g., SpaceX succeed in establishing a Martian colony. I’d always heard that that’s no solution to population, unless you have an awful lot of time to spend, and it seems so: with replacement-level TFR and an initial population of 7 billion, to lower the population by 1 billion in 200 years, you have to get 5 million emigrants a year, which is somewhere northwards of 10k every day.

    More sinisterly, that would also describe the effects of increases in mortality. Turns out that to bring human population below 1 billion by 2050, it would take replacement-level fertility *plus* 200 million additional deaths every year. Even WW II only managed about 15 million deaths per year, taking the upper-limit casualty figures, and rounding the war’s duration down to 5 years.

    Which dramatizes even more forcefully why I insisted above that population is not a useful lever in addressing the climate crisis in the nearish term. That doesn’t mean it shouldn’t be considered, of course, for reasons given above by several people–and in particular I note here zebra’s comment about population as a longer-term issue. (Was that at #54 FV? I’m not seeing it on this thread.)

  35. 85

    PM, #76–

    Where is the discussion of Carbon Budgets, in order to align with the massive conversation with the 2018 IPCC Special Report, etc.?

    That’s a good question, but I’m guessing the answer lies in the terms of reference for NCA 4 and its previous iterations. There’s a lot of emphasis on impacts, I note (with appreciation).

  36. 86

    Further yet to PattiMichel’s question, it occurs to me too that it would be problematic to get too deeply into carbon budget in a national-level report, in that the budget is fundamentally *global*. So how do you apportion a national share of that budget, especially when historical reality is way out of whack with per capita equity?

    All that said, Chapter 29 does address mitigation and adaptation in a summary sort of way, and includes the estimate that we were talking about above.

    And speaking about the discussion about damage to the US economy and RCPs, the relevant figure is 29.3. I’d note the uncertainty ‘whiskers’ on the projected values; for 15 F temperature rise the 90% range seems to be from about -5.5% of GDP up to about -15%, so you can’t say they don’t acknowledge considerable uncertainty.

    (Though I have to ask: is it really plausible that a 3 C rise–5.2 F–is only going to cost the US a little over 2% of GDP? Of course it’s true that rebuilding after disasters actually *boosts* GDP, since GDP is agnostic as to the utility value of any given form of economic activity–one of its flaws as a metric.)

    I note further that the left graph does indeed show the current emissions trajectory as a good match with RCP 8.5.

  37. 87
    David Young says:

    Zebra, Zhou eat al already showed that sensitivity of their GCM could be adjusted over a broad range by different credible values of the parameters in their cloud and precipitation sub grid models. This is not a surprise as it’s the case with turbulence models too. So it is highly unlikely that current parameter values are “accurate”. And the model form itself simply can’t be right for such complex processes. A lot more work is needed.

  38. 88
    zebra says:

    Kevin McKinney,

    Get a grip, dude– what is FV?

    And, I’ll say this very slowly: I was hoping you would respond to my comment #54 (which is right there on this thread), on Forced Responses (FR), which is the correct venue for mitigation. Got it?

    But now I will respond to your latest comments, and my response will be on FR. OK? Hope to see you there!

  39. 89

    zebra, #88–

    “What is FV?”

    Apparently you already figured that out.

  40. 90
    zebra says:

    #87 David Young,


    I’m stunned! Changing the input for the model of a chaotic system changes the output?? Who knew!? [end sarcasm]

    Perhaps you could read what I said again:

    If I had the models and the computing power, I would tweak some of those parts you suggest and see which direction the variable in question goes. Then I would look at (possibly) changed other variables in the system, and how they agree with the data, after those tweaks. Very basic.

    Of course you will get different results. The question is how all of those results compare with the actual data, which you seem to have missed in my statement.

    I asked you to be more specific, and explain why you think the discrepancy in that one measurement is so significant. Can you give some actual numbers, where you adjust the model, get closer to the RSS value for the tropics, and don’t create a discrepancy somewhere else?

  41. 91
    JCH says:


    Little tip for dealing with DY. He frequently misremembers.

    He means Ming Zhao, not Zhou, of the Global Fluid Dynamics Laboratory at Princeton, and I believe this is the study to which he is referring:

    Uncertainty in Model Climate Sensitivity Traced to Representations of Cumulus Precipitation Microphysics

  42. 92
    David Young says:

    Zebra, You can read the paper for yourself, assuming it not too technical for you. I assume the lower ECS results are in better agreement with observations. The problem here is that like turbulence models, these cloud and precipitation models are almost certainly incapable of doing a good job over the globe with all its different weather patterns and detailed types of precipitation.

  43. 93
    jgnfld says:

    Avid @ #87…

    YOU can help with exactly what you are suggesting by going to and installing the BOINC background app. It is running at about 142 petaflops at the moment so a goodly amount of work is getting done. But you could do your part and help add more power.

    You see, as zebra notes, scientists constantly are using perturbed inputs to estimate the state-space the models follow with said perturbed inputs.

    Be part of the solution instead part of the problem.

  44. 94
    Ron R. says:

    Patrick, #69. Finally got a chance to read The Insect Apocalypse. I too have noticed the dearth of “bugs” compared to decades past. We humans have won the millennium long war to make the world “safe” for us, on all levels. There’s been so much wrong with that though. Even today, the most toxic anti-bug chemicals are freely sold in Home Depot, Lowe’s and hardware stores the world over. To walk down the aisles these plethoras of poisons are found in one needs to hold one’s breath the smell is so bad. Their garden nurseries are full of plants that have been sprayed with pesticides by their vendors (I’ve been told by one such vendor) so that the occasional leaf nibbling “bug” will not “ruin” their appearance with tiny holes and thus their salability. Yet there are bees visiting the Lavenders, the Gaillardia and other flowers. No one wants to upset the chemical industry or their vendors.

    I once lived across the street from a woman who was so terrified of bugs that she had her place, yard and house, professionally sprayed by Orkin once a month. We moved, but I went back for a visit a few years and heard that she’d died a slow, painful death of small tumors spread throughout her body.

    I also noticed in the article the reference to a “shifting baseline”, wherein younger generations are unaware of, and thus not sensitive to, the loss of biodiversity that older generations remember (when they care to). Robert McLachlan, #40 on Forced Variations cites an article that also references SB.

    And I appreciated this statement: ”We’ve begun to talk about living in the Anthropocene, a world shaped by humans. But E.O. Wilson, the naturalist and prophet of environmental degradation, has suggested another name: the Eremocine, the age of loneliness.”

  45. 95
    zebra says:

    #92 David Young,

    ” I assume the lower ECS results are in better agreement with observations. ”

    Zhao et al:

    Based on the mixing inferred from observation and reanalysis data, they suggest that the models with higher climate sensitivity may be more realistic for predicting future global warming.

    Perhaps you are the one for whom the paper is “too technical”?

  46. 96
    David Young says:

    Well, mixing is a lot harder to measure than temperature and as I pointed out above, there is a difference of 2.0 between 40 year trends in the tropics between MRSS and CMIP5. Certainly that implies the TCR of the models are mostly dramatically too high.

    I disagree with their statement, assuming you quoted it accurately and in context. It would be interesting to get their comment on the MRSS chart.

  47. 97

    #96, DY–

    there is a difference of 2.0 between 40 year trends in the tropics between MRSS and CMIP5.

    First, what is “MRSS”? It’s not mentioned in the RSS page discussed, nor is that acronym used in the Santer et al. (2017) paper linked there.

    Second, presuming that “MRSS” is meant to refer to the RSS v.4 record shown on the RSS page linked above, then just no. There is no such difference. The graphs given show temperature anomaly over time, so further calculation would be needed to determine the 40-year trend, but since the total warming is only around a degree C, it’s quite plain that the difference between the two 40-year trends must be less than that. (Of course “2.0” doesn’t specify units, so maybe something else is meant.)

    Certainly that implies the TCR of the models are mostly dramatically too high.

    No, it most certainly does not. In the first place, it’s not clear how good the satellite measurements are; remote sensing of atmospheric temperature is not a straightforward matter, and there is a history of ‘error correction’ (and even of error correction in which climate model projections were vindicated with respect to UAH particularly.)

    There’s a discussion by statistician “Tamino” here of the satellite *surface* records compared with the surface record (which is a hell of a lot more robust than the mid-troposphere record, for obvious reasons.) It notes significant differences between satellite data and the instrumental record, and between differing satellite data. So one can’t simply assume that observations are correct and the models are therefore wrong. DY dismisses observational error as a possibility, but a glance at the graphs shows that differing error corrections in satellite temp algorithms do produce, and have historically produced significant discrepancies over decadal time scales.

    The same author compares satellite mid-tropospheric satellite observations to the radiosonde data, finding among other things that:

    …the trend according to RATPAC is 1.91 +/- 0.51 deg.C/century, in excellent agreement with RSS TTT but flatly contradicting UAH TMT.

    It’s also in fair agreement with what the ensemble mean from CMIP 5 is, insofar as one can ‘eyeball’ it–the 1 C estimated above for 40 years of RSS translates to a 100-year rate of 2.25–not a “differance of 2.0.”

    Turning to the Santer et al. paper mentioned above, it says:

    We find that in the last two decades of the twentieth century, differences between modelled and observed tropospheric temperature trends are broadly consistent with internal variability.

    That is not the case for the early twenty-first century, however:

    …model tropospheric warming is substantially larger than observed; warming rate differences are generally outside the range of trends arising from internal variability. The probability that multi-decadal internal variability fully explains the asymmetry between the late twentieth and early twenty-first century results is low (between zero and about 9%).

    If the differences were due, as DY suggests, to model physics, then one might ask how it is that the same model physics produced such different results in two different periods? Indeed, Santer et al remark that:

    It is also unlikely that this asymmetry is due to the combined effects of internal variability and a model error in climate sensitivity

    Their answer?

    We conclude that model overestimation of tropospheric warming in the early twenty-first century is partly due to systematic deficiencies in some of the post-2000 external forcings used in the model simulations

    Differences in prescribed forcings, of course, have nothing whatever to do with climate sensitivity, whether TCR or any other flavor.

    So there are viable–indeed, probable–alternate explanations.

    Finally, I would challenge DY to specify what he thinks the link between TCR and tropospheric warming rates is? As a clarifying question, let us suppose that 1) the mid-tropospheric warming rates did actually diverge as seriously as he thinks, and 2) the apparent good agreement between the instrumental surface record and the CMIP ensemble, as seen here, is also correct.

    Now, let’s consider the definition of TCR:

    Although climate sensitivity is usually used in the context of radiative forcing by carbon dioxide (CO2), it is thought of as a general property of the climate system: the change in surface air temperature (ΔTs) following a unit change in radiative forcing (RF), and thus is expressed in units of °C/(W/m2).

    Let me emphasize: “…the change in surface air temperature (ΔTs)…”

    So, please explain to me why a property defined in terms of SAT–which seems to be well-simulated in CMIP5–“must be” seriously askew because of a mismatch in tropical mid-tropospheric temperature?

  48. 98

    In addition to what I said previously, here’s what Santer and Mears say about the notion that climate sensitivity in models is generally much too high:

    But what if climate models really were a factor of three or more too sensitive to human-caused GHG increases, as claimed by the majority side of the subcommittee? The telltale signatures of such a serious climate sensitivity error would be evident in many different comparisons with observations, and not just over the last 18 years. We’d expect to see the imprint of this large error in comparisons with observed surface temperature changes over the 20th century, and in comparisons with the observed cooling after large volcanic eruptions. We don’t. There are many cases where observed changes are actually larger than the model expectations, not smaller.

  49. 99
    zebra says:

    Kevin McKinney,

    Nice exposition, Kevin, but I have been asking him the same question(s) all along, and you clearly are not going to get a coherent answer.

    I usually just give up when people cite papers that they haven’t read themselves.

    (And, in fact, the paper he cited wasn’t even really relevant to the “troposphere anomaly” question.)

    As for where errors might come from, my experience with instrumentation puts those particular measurements at the very bottom of what I would have confidence in. Going back again those many decades, I once struggled with such equipment… on the surface of the planet, in a climate controlled lab, with the detector and the (unitary) source never more than a meter apart.

    Given the near-impossible conditions with which they must contend, and the nature of what they are trying to measure, I bow down to the satellite people if they are actually only off by a factor of two.

  50. 100
    David Young says:

    Kevin, What I meant to say is that there is a difference of a factor of 2 in the warming rates. Sorry about that.

    It seems quite unlikely to me that forcing estimates are off by that much.

    The rest about the Santer paper and the asymmetry doesn’t say anything really about model physics at all. If you want to add something here I would suggest googling Rayleigh Taylor instability and read up a bit on it and then explain how our experience with turbulence models is not applicable to convection.