The plausibility of RCP8.5

I’m on the train to Cambridge for a meeting that starts tomorrow. Since I had nothing better to do, I thought I would have a quick look at the RCP8.5 data. There’s been quite a lot of criticism of the National Climate Assessment, that I discussed in this post. This is mostly because it used RCP8.5, which some claim is unrealistic. Firstly, it didn’t only consider RCP8.5, and the point about RCP8.5 is not that it is somehow likely, but that it is plausible. We want to consider a range of pathways, including those associated with increasing emissions.

Something that is often over-looked is that RCP8.5 is really a concentration/forcing pathway, not an emission pathway. There are a range of emission pathways that could lead to such a concentration pathway, including some with cumulative emissions as low as 1500 GtC. What I wanted to do was quickly check how cumulative emissions by 2100 varied with the year in which emission reductions start, assuming that they then reduce at 3% per year.

Essentially, we could largely avoid RCP8.5 if we started reducing emissions, at 3% per year, before ~2040. Bear in mind, though, that RCP6 is associated with cumulative emissions of about 1500 GtC, so avoiding RCP8.5 doesn’t mean that there wouldn’t still be a reasonably large change in radiative forcing. After 2040, we would need to reduce emissions at a rate greater than 3% per year if we wanted to have a high chance of avoiding an RCP8.5 pathway.

So, if people really think that RCP8.5 is impossible, that would seem to suggest that they think we can reduce emissions rapidly sometime in the future, or that we’ll start doing so soon anyway. If RCP8.5 is implausible because of fossil fuel availability, or future cost, it would still seem to make sense to think about alternatives sooner, rather than later. The longer we wait, the more rapid the transition will need to be, irrespective of the reason for doing so.

Links:
Tweets by Richard Betts and Gavin Schmidt.

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85 Responses to The plausibility of RCP8.5

  1. I did a bit more work on this and produced the figure below which shows how the annual percentage reduction changes with start year if we want to keep cumulative emissions below 1500GtC (i.e., giving us a high chance of avoiding RCP8.5).

  2. Willard says:

    > Firstly, it didn’t only consider RCP8.5, and the point about RCP8.5 is not that it is somehow likely, but that it is plausible.

    Like all modalities, the concept of plausibility is problematic.

    It is plausible for Manchester United to lose 5-0 to Newcastle:

    I still wouldn’t bet on it.

    The best may be to simply lay down the main assumptions of all scenarii.

  3. verytallguy says:

    The longer we wait, the more rapid the transition will need to be, irrespective of the reason for doing so.

    Precisely. There is a double bind here:

    If we can extract sufficient fossil fuels to deliver RCP8.5, we will fry, so we should mitigate emissions rapidly

    If there are insufficient fossil fuels to deliver RCP8.5 then we face a potentially catastrophic resource crunch, so we should mitigate emissions rapidly.

  4. The plausibility of RCP8.5 has very little to do with science, maths, or indeed anything that’s logical. Instead it has almost everything to do with human behaviour. Where are the psychologists?

  5. Willard,
    As I see it, the problem is that there are multiple scenarios that could lead to an RCP8.5 concentration pathway. Plus, there are carbon cycle feedbacks that could also start to operate and lead to a higher concentration pathway. At the 4 main RCPs are quite simple; low, medium, miedium-high, high and you can associate them with different levels of warming and different levels of impact. We can then associate these with emission pathways which can provide some idea of what we would need to do if we wanted some of the severe impacts.

    As I may have said before, worrying too much about the details seems unnecessary. Start by finding ways to get emissions to reduce, and then start to think about how fast to do so.

  6. Willard says:

    > As I may have said before, worrying too much about the details seems unnecessary.

    I’m more interested in countering that kind of ClimateBall move:

    This is a common trick to hide the many different ways RCP8.5 can obtain.

  7. Willard,
    Do you mean countering the Climateball move in which someone suggests the details of RCP8.5 aren’t realistic while ignoring that there are actually a range of social pathways that could lead to an RCP8.5 concentration pathway?

  8. vtg,

    If we can extract sufficient fossil fuels to deliver RCP8.5, we will fry, so we should mitigate emissions rapidly

    If there are insufficient fossil fuels to deliver RCP8.5 then we face a potentially catastrophic resource crunch, so we should mitigate emissions rapidly.

    Yes, that’s a good way to put it.

  9. Willard says:

    > Do you mean countering the Climateball move in which someone suggests the details of RCP8.5 aren’t realistic while ignoring that there are actually a range of social pathways that could lead to an RCP8.5 concentration pathway?

    Yes, something along these lines:

    (1) RCPX.Y presumes P.
    (2) P is implausible.
    (3) Thus RCPX.Y is implausible.

    The first premise looks unsound to me, and saying so looks like Richard and Gavin’s approach. However, this doesn’t offer any proper way to look at the various possible packages. It’s easier to argue that a population boom is implausible than to argue that, taken together, “assumptions about high population,” “relatively slow income growth,” and “modest rates of technological change and energy intensity improvements,” (as we read in Riahi et al) are implausible. For we could imagine a mix of population, growth, and technological changes that makes RCP8.5 relevant.

    A most expedient counter seems to flip the table on those who argue that the technological changes honest brokers expect will lead us to lower RCPs. This seems to be Keith Anderson’s line of attack.

  10. billbedford says:

    >This is a common trick to hide the many different ways RCP8.5 can obtain.

    …and what would some of those be?

  11. bill,
    One common example is to say something like “RCP8.5 requires a population of 12 billion. That won’t happen, so it’s not possible”. However, this is simple one possible pathway. It is possible to follow an RCP8.5 pathway even if the population doesn’t get that high.

  12. Willard says:

    > and what would some of those be?

    I just gave one. There’s also a reason why I speak of honest brokers.

    Those who like you peddle the CAGW meme may not need any argument at all.

  13. angech says:

    I get that there are potential horrific outcomes with CO2. The problem is really if you are right it almost must by it’s very nature be unavoidable and if you are wrong you may be doing harm when no action was needed.
    I agree with fossil fuel reduction where sensible, practical, replaceable, at the same or lesser cost by alternative energy sources. I abhor the destruction wrought by ever increasing human hordes. Ultimately though we take steps to slowly get it right or we suffer the consequences and someone, somewhere will come through that better off.
    My enjoyment of my lifestyle, such as it is, for the shorter time left older people, is tempered by the fact that I try not impose my views on others, except in opposition to such views being imposed on me.
    Keep pushing the science and hope it comes up with answers.

  14. Hyperactive Hydrologist says:

    Carbon cycle feedback
    Methane hydrates – if we find a economically viable extraction method we may need a scenario above RCP 8.5

  15. Chubbs says:

    RCP8.5 is the only scenario with increasing methane and N20. So while RCP8.5 CO2 is unlikely, similarly the other RCPs have unrealistic methane and N2O, at least for the near future. None of these scenario’s are going to be right in detail.

  16. Chubbs says:

    Instead of “RCP” which has no communication value. Better to use past climates to label the scenarios:
    RCP2.5 – Pliocene
    RCP4.5/6 – Early Eocene
    RCP8.5 – PETM or late Permian

    https://www.nature.com/articles/ncomms14845/figures/4

  17. Fergus Brown says:

    I’ll repeat. Focussing on the sharp end hypotheticals is a risky business, and not necessary or relevant, unless you want to produce a headline which says ‘ look how bad this could be’ for the ignorant.

    The ‘cost’ of an RCP8.5 scenario is about as bad a way of getting across the message that action now is not just the best answer, its the only one – First, we need to focus on a better way of expressing the nature of the coming storm than ‘oh, this could be expensive’, then we need to remind everyone that every fraction of a degree of avoidable warming is a nail in thousands of coffins, somewhere, and we do not want to live in a world where increasing ‘acceptable collateral damage’ is something tolerable; it’s fucking inhuman.

  18. Mitch says:

    People always seem to get overly disputatious about the RCP’s. Again, they were designed to cover all the emissions and timing, so that apples to apples can be compared between models in CMIP. They were supposed to span possible alternatives

    What people will actually do is the largest source of variation in predicted (projected?) climate change over the next century. Also, as stated above, we need to mitigate both for climate reasons and for resource reasons.

  19. billbedford says:

    >Willard
    >Those who like you peddle the CAGW meme may not need any argument at all.

    FYI As far as I am concerned:
    Human-caused global warming is a theory.
    The assertion that human-caused global warming is dangerous is a hypothesis.
    So why so many seemingly intelligent people need to believe that the world will go to hell in a handcart in, oh, twelve years, does need some explaining.

    And for the absence of doubt, I believe the idea of RCPs is nested well inside the CAGW meme and that a discussion about whether one of them is plausible would be just the sort of debate that medieval theologians would have excelled at.

  20. The world is going to “hell in a handcart” now. Your witness: reality. Here’s a good read on that.
    https://www.newyorker.com/magazine/2018/11/26/how-extreme-weather-is-shrinking-the-planet
    “How Extreme Weather Is Shrinking the Planet
    “With wildfires, heat waves, and rising sea levels, large tracts of the earth are at risk of becoming uninhabitable. But the fossil-fuel industry continues its assault on the facts.”

    Your other witness, daily weather. Wunderground’s Category 6 blog regularly releases up-to-date information as well as lists of costs, both financial and human, as the years go by. The most recent is a shocker! (I didn’t open it to find this, but it is characteristic of the worst kind of news for the distortionosphere style of “fake news” style of lies.)
    https://www.wunderground.com/cat6/Court-Forces-University-Arizona-Release-Climate-Scientists-Traditionally-Confidential-Emails

    My father and I support the Climate Science Legal Defense Fund, which is an important effort with nearly 100% of the money going to help scientists stick to the truth, rather than distortion.
    https://www.csldf.org/

  21. JCH says:

    Let’s see, 12 years, call it 2031. Show me somebody who said the world will be hell in 2031.

  22. The Very Reverend Jebediah Hypotenuse says:

    #1)

    Human-caused global warming is a theory.

    #2)

    The assertion that human-caused global warming is dangerous is a hypothesis.

    #3)

    So why so many seemingly intelligent people need to believe that the world will go to hell in a handcart in, oh, twelve years, does need some explaining.

    #1) and #2) are not evidence of anything, so why billbedford should be surprised at the requirement for an explanation for his hyperbolic #3) should be unsurprising.

    At least medieval theologians used syllogisms.

  23. verytallguy says:

    “And for the absence of doubt…”

    Your ramblings may be lacking in more than just doubt, Bill.

  24. Willard says:

    ­> I believe the idea of RCPs […]

    RCPs are more than an idea, Bill, and everything conspires for contrarians to peddle the CAGW meme.

    You are more than welcome to go peddle it at Judy’s.

  25. Greg Robie says:

    When isn’t plausibility problematic? (Or, when Willard is the first comment, the comment thread could possibly be interesting!) 😉

    So, what is the social problem that a linguistic and conceptual dance of ‘possibility’ and ‘plausibility’ solves? And what is the music that’s playing for this dance? Isn’t it observable than neither possibility nor plausibility are socially anything other than the product of a rich imagination and/or a psychosis when there is no socially perceived risk concerning what is talked about? And when risk is socially perceived, doesn’t a capacity to effect a solution thereby become the music of the dance: social power? Doesn’t the existence and functions of the amygdala dictate that psychologically, risk always is, regardless of perception and motivated reasoning?

    For the possibility and plausibility of socially perceived risk to exist in the first place, there are the mitigating trusted folk tales such as the “Chicken Little”/”Henny Penny” stories, and “The Boy Who Cried Wolf” story. The evolution of the protagonist’s gender in the first, and what it is in the latter, are particularly interesting to me regarding the social tasks of observation, responsibility, and power … but I’m not going to say much about that. 😉 However, the “sky-is-falling” series is instructive concerning the alternate endings of the fox-and-food one, and a king explaining away a perceived risk one … which I will expand on.

    Here at ATTP, the role of observation concerning risk is focused on. As such, and with various moderation tools, a kingly-like responsibility is effected to minimize hysteria’s role in defining social power. The responsibility for factual observation can be observed to be informed here at ATTP by both folk stories. Power, to the degree, knowledge is power, is both a given (no story needed), and fought over in the ATTP comment stream. And aren’t we’re all wet? 😉

    Beyond the Ivory Towers, the folk tales have been skillfully played within social power grab dynamics. The benevolent King of trusted tales is dethroned, if not dead. Any assumed power of being the fountainhead of regal advice (ie, the asserted limited responsibility/role of science in policy matters that is often asserted on ATTP) is irrational. In fact, it feeds into the destruction of the assumed power … because physics defines knowledge as action AND that knowledge says ‘the sky is falling/[plausibly fallen]’.

    Observation. Responsibility. Power. Risk. Our Socio-PyschoImmunoNeuroEndocrinology (SPINE) effect them all. Therefore – and doesn’t our history reveal that – humanity stands or falls because of its dancing to power while wearing the two shoes of possibility and plausibility?

    Hysteria and false alarms are known social tools of power. Within this time of ClimateBall(TM), the power of reason that allowed western culture to emerge from the abuse of power-via-mysticism of the Dark Ages, is dethroned. Isn’t ClimateBall(TM) a synonym for mysticism; a descriptor for the social affect of motivated reasoning?

    Regardless, Foxes are. Wolves are to be watched for. We [and our only home] are being consumed by our wolf in cancers clothing: our trust in the mythic of limited liability law enabled CapitalismFail’s GREED-as-go[]d. Such is a deniable risk those for whom abusive power clouds observation; Orwellian-like defines a practiced right to be irresponsible, as freedom.

    Now for the substance of my comment regarding plausibility and the RCP8.5 as “a concentration/forcing pathway, not an emission pathway” and possibilities. A while back, after experiencing the Inuit elders’ observations concerning increased seasonal shifts in the tropopause dismissed out-of-hand here, I considered what else I might be responsibly do with their observations in the face of my lack of knowledge (i.e., power) here at ATTP. It occurred to me that I might be able to use an astronomy program I have to begin to quantify their observations about a shift in the location of the setting of the sun at the end of the Arctic day and that two hour shift in illumination regarding the length of hunting time they were experiencing.

    While doing some cleanup before the family gathering here Thanksgiving, I ran across my notes from this effort. This explanation that RCP8.5 relates to forcings inspired me to see if I could quantify what appears to be a seasonal addition of solar incidence of a portion of the solar incidence that warms ~2° worth of additional latitude in the area of the Arctic Circle during the Arctic day.

    I’ve tried to responsible in my rough calculates that this 2° shift could plausibly justify a possible addition of 3.6547322e+12 m2 receiving ~200W/m2. Does anyone here know, or possible know anyone who, or possible know anyone who might plausibly know whether, the resulting 7.3094644e+10 kW might possibly be significant and plausibly explain the irresponsible underestimating of the observed changes in the Arctic crysophere relative to the possibly relevant climate models?

    It seems plausible that toothless elders might possible have valid observation about something that can best be seen while living life where such is dependent on astute observation. Possibly such is threatening to the power derived by regal advisors of a deposed King whose Ivory Towers’ [yet] provide plausible shelter from the storm?

    If such a possibility posed a plausible risk to the assumed social power derived from knowledge, is the previous summary dismissal of the scientific value of the Inuit’s observation of no social risk to the assumed power? Is the plausible assumption of power possibly irrational? Is it plausible that, to the degree such is possible, that this inquiry could be considered responsible? ClimateBall(TM) withstanding, is it that any possible risk it poses to plausible power, be observed differently? 😉

  26. Mircea Dochia says:

    Regarding RCP 8.5 I think that the question is not if but when it happens. The history doesn’t stop on 2100…. If it doesn’t happen in 2100, it will happen in 2130 or 2150…
    Humanity will burn everything it can and then it will invent new things to burn… Energy is the basis of prosperity and I do not see any social action that will be able to stop/diminish the hunger for energy.
    When crisis will start to be costly climate engineering will be the obvious and only solution to the climate crisis. An array of mirror satellites (mylar) deflecting the sun is very feasible and not expensive at all. Plus… will bring a nice profit to whoever owns them (USA, Russia, China – SpaceX will be more then happy to oblige).
    Why this type of solution doesn’t work in your view? Why you do not talk about this (maybe is not the right thread for this question… It would be interesting a talk about realistic solutions) ?

  27. verytallguy says:

    Why this type of solution doesn’t work in your view?

    1. Ethics and governance
    2. Feasibility and practicality
    3. Does not address ocean acidification
    4. Energy will become sustainable eventually, by definition. Earlier switch to sustainable = less shock to change.

  28. weogo says:

    Hi Mircea,

    Energy is one basis of life, along with water, soil, air, a life-conducive climate and the other basics.
    Prosperity is having a couple spare spoons, forks(or chopsticks) and knives for guests,
    all the way up to a sports car in every driveway around the world.
    How much ‘prosperity’ brings us joy?
    Bhutan is actively working to define a moderate consumption ‘good life’ with
    their GNH scale and social action. It can be done.
    https://en.wikipedia.org/wiki/Gross_National_Happiness

    Plants need sunlight.
    We eat plants, or animals up the food chain that eat plants.
    My understanding is that plants have a significant role in sequestering carbon.

    How much sunlight do you imagine blocking?

    Thanks and good health, Weogo

  29. Greg Robie says:

    As long as fantasy’s plausibility is being considered, and expanding on #2, geo-positioned solar screening would be … well … geo-positioned (i.e., not solar positioned!), so this fantasy would thereby require a massive deployment of a dynamically regulated wave-like opening and retracting of solar screening of the array. If the aforementioned 7.3094644e+10 kW is, and is missing from the models effecting the arrays’ wave, and/or that extra warming is dynamic relative to lagged climatic response to any programmed control of the wave, isn’t that sarcastic rhetorical question “what could go wrong?” a plausible understatement?

    Also, in terms of #4, a patented technology for ‘sustainable’ rentable energy is that same deployed array concept with solar panels and computer controlled microwave zapping of the energy to earth-based, grid connected, receivers/’inverters’. PG&E has contracted regarding the patents. Peaceful co-existence of these two arrays’ possible competing needs is plausible (but see #1).

    Einstein is attributed the observation that the thinking that creates a problem cannot be used to imagine its solution. Whomever had it, it is profoundly sapient, particularly in our time of a paradigm shift.
    A review of human history reveals an observable repeated pattern of sociological shifts from rational to irrational paradigms, and whether one is initiated from an ostensively religious or rational perception. Such shifts have effected a destruction and redistribution of perceived wealth. Does the truism concerning the two constants and change need a reboot of rationalism within our time of change regarding trusted feelings about both freedom and wealth? Aren’t there plausibly three constants: death, taxes, and extinction?

  30. RCP 8.5 is now 11 years old, and ree decades have passed since Hansen and others warned of an immanent transition from linear to exponential temperature rise from anthropogenic forcing.

    Yet despite the alarming increase in CO2 and the rest of the GHG’s, the trajectory of global temperature rise remains stubbornly linear.

    To keep 8.5 “plausible”. decadal warming must at some point accelerate past 8.5 degrees divided by the century’s remaining number of decades, a criterion yet to be met even by the less pessimistic trajectories, and the longer it takes to get to the jumping off point for RCP’s 2.5 through 6, the less supportable the rhetorical plausibility of 8.5 as an outlier.

    The policy problem may accordingly be one of a bad choice of time scale- the outlier pathways are less implausible if their end points are considered as 10 generations rather than 10 decades out.

  31. Willard says:

    Incredulity is cheap:

  32. verytallguy says:

    Russell, the 8.5 in RCP8.5 refers to forcing in W/m2, not temperature rise in degrees.

    A link to claims of “exponential” temperate rise being “immanent” (sic) would also be nice.

    (Short version: bizarre comment – has your account been hacked?)

  33. billbedford says:

    >Regarding RCP 8.5 I think that the question is not if but when it happens. The history doesn’t stop on 2100…. If it doesn’t happen in 2100, it will happen in 2130 or 2150…

    That depends on whether history is linear.

    >Humanity will burn everything it can and then it will invent new things to burn…

    It is worth remarking that the only countries that have actually reduced their CO2 emissions significantly have used the ‘burn everything route’

    >When crisis will start to be costly climate engineering will be the obvious and only solution to the climate crisis.

    I suspect that the climate crisis will always be in the future and people will just cope with whatever weather comes their way the same way as they always have.

  34. verytallguy says:

    I suspect that the climate crisis will always be in the future and people will just cope with whatever weather comes their way the same way as they always have.

    Just coping is a great strategy. Worked for the dodo. Worked for smallpox. What could possibly go wrong for climate?

  35. verytallguy says:

    Reminds me of the JFK gambit, Willard.

    All great and honorable actions are accompanied with great difficulties, and both must be enterprised and overcome with answerable courage.

    We choose to go to the moon in this decade and do the other things, not because they are easy, but because they are hard, because that goal will serve to organise and measure the best of our energies and skills, because that challenge is one that we are willing to accept, one we are unwilling to postpone, and one which we intend to win.

    It is for these reasons that we should do nothing and just wait for someone to invent an antigravity machine.

    https://coveredinbees.org.archived.website/node/459.html

  36. billbedford says:

    >Just coping is a great strategy. Worked for the dodo.

    Yep sure, the dodos could have formed themselves into an armed militia and repelled the hungry sailors.

  37. billbedford says:

    >C’mon, Very Tall.
    >Future is bright.

    We don’t need no pixie dust, just evolution:

    Those organisms/species/societies/countries best able to deal with change are likely to prosper, those that can’t or won’t will dwindle.

  38. Willard says:

    Dwindle dwindle little stars:

    Plummeting numbers of mammals, reptiles, amphibians, birds and fish around the world are an urgent sign that nature needs life support. Our Living Planet Report 2018 shows population sizes of wildlife decreased by 60% globally between 1970 and 2014.

    For the last 20 years, scientists from ZSL, WWF and other organisations, have been monitoring changes in the populations of thousands of animal species around the world. Sadly, they’ve concluded that the variety of life on Earth and wildlife populations is disappearing fast.

    https://www.wwf.org.uk/updates/living-planet-report-2018

    Everything is fine.

  39. The Very Reverend Jebediah Hypotenuse says:


    Those organisms/species/societies/countries best able to deal with change are likely to prosper, those that can’t or won’t will dwindle.

    Absolutely!

    Once the ocean becomes anoxic, and CO2 hits 1000+ ppm, plants will again become the second-most dominant life-form on Earth.

    Thermophile bacteria have always had the brightest future.

  40. verytallguy says:

    We don’t need no pixie dust, just evolution:

    Those organisms/species/societies/countries best able to deal with change are likely to prosper, those that can’t or won’t will dwindle.

    Roaches for the win.

  41. vtg, roaches, squid, jellyfish, ticks, algae (yes, flora not fauna) … and perhaps tardigrades. Big self-indulgent mammals treating earth as a combined dump and cornucopia, citing self-referential god as their excuse to dominate rather than steward, not so much.

    This is another tl/dr, but a fascinating article nonetheless: https://www.nytimes.com/2018/11/27/magazine/insect-apocalypse.html The Insect Apocalypse Is Here

  42. VTG , thanks for the reminder that Six Degrees is no longer in print. I should have written 4.5 C
    Word of the implausibility of all the model trajectories projecting 6-9 C of warming by 2100 seems slow in reaching lede writers at The Guardian & TV.

  43. verytallguy says:

    Russell, a link to those exponential claims you make would be nice. Or has the custom for referencing not yet reached Harvard or the Climate Institute of Washington DC?

  44. verytallguy says:

    Thanks Susan. A bit depressing, that.

  45. Willard says:

  46. The Very Reverend Jebediah Hypotenuse says:

    The RMS Titanic is still unsinkable! Details at 11…

  47. lerpo says:

    “(Th)ree decades have passed since Hansen and others warned of an immanent transition from linear to exponential temperature rise from anthropogenic forcing.”

    It looks like temperature rise has continued to accelerate:

    1930-1960: 0.012 C/decade
    1960-1990: 0.098 C/decade
    1990-2018: 0.194 C/decade

    But I think we’ll need to get CO2-eq up towards 1250 ppm as we approach century end if we want to test RCP8.5.

  48. VTG what part of “accelerating ” can’t you integrate ? Since the 80’s we have been told to expect temperatures to rise N degrees by 2100 , but those seeking to normalize that view remain indisposed as they were in the last century to name the decade will see the first N / 10 degree rise.

    After decades of climatic bracket creep their sensible reluctance to bet on their own rhetoric has begun to corrode the credibility of the precautionary principle as first adduced.

    A hydraulic cherry picker makes a bully pulpit, but the annual acceleration of warming ( and radiative forcing for that matter ) remains stuck in the third decimal place three decades after Mr. Gore decalred “: “My purpose is to sound an alarm, loudly and clearly, of imminent and grave danger, and to describe a strategy for confronting this crisis ” ( Washington, D.C., May 1, 1989)

    The IPCC’s sober adjustment of the range of scientific expectation has not much moderated climate publicists’ continuing emphasis on the outliers

  49. verytallguy says:

    So, no link to claims of exponential rises Russell, following no acknowledgment that the 8.5 is forcing, not temperature.

    When did the custom for doubling down reach Harvard and the Climate Institute of Washington DC?

  50. Mircea Dochia says:

    billbedford,

    “That depends on whether history is linear.”
    – Linearity is assumed in the scenario (no changes to business as usual, no disruptions either in technology or fossil fuel supply). I personally think that even with small to medium reductions we’ll still eventually get there.

    “It is worth remarking that the only countries that have actually reduced their CO2 emissions significantly have used the ‘burn everything route’”
    – Yes, indeed… but it is because they burn gas now instead of coal. Unfortunately the reduction is fairly small and I do not think that the coal will remain in the ground for long.

    I suspect that the climate crisis will always be in the future and people will just cope with whatever weather comes their way the same way as they always have.
    – Nicely said… yes, it will always be a weather event. Climate is a social construct (a history of weather events and projections of future weather events)… It happens that in order to cope with weather events one has to take climate and climate projections into consideration.

  51. Mircea Dochia says:

    Hi weogo,
    “How much ‘prosperity’ brings us joy?”
    – A better house, car and vacation then the neighbours… It is a competition ingrained in our genes… I do not see it ending. I think it’s part of our humanity.

    “My understanding is that plants have a significant role in sequestering carbon.”
    – This is also my understanding. People here might disagree however…

    “How much sunlight do you imagine blocking? ”
    – It is my understanding that 1% is enough. The financial profit can be huge and will allow space technology and space habitation development. With military space force established and private space exploration companies in full growth the next move will be to find a lucrative activity. (note: I personally think that humanity’s future is out there in space… If we remain on earth we’ll dim-out… as such I am pretty biased)

    All the best, Mircea

  52. Mircea Dochia says:

    verytallguy

    1. Ethics and governance
    – Ethics? It would be interesting if you could elaborate.
    2. Feasibility and practicality
    – If it will bring a profit then it will be practical. It will allow for space technology and space habitation development. It will justify the existence (and the budget) of Space Forces. It is clear to me that space exploration needs a lucrative activity in order to expand… this one looks like a low apple…
    3. Does not address ocean acidification
    – yes, indeed it doesn’t…
    4. Energy will become sustainable eventually, by definition.
    – It’s not about sustainability… it’s about price. Cheaper always wins… You have the elite who can afford to pay for some luxury… but the masses… always cheaper…

  53. verytallguy says:

    It’s not about sustainability… it’s about price.

    No, it’s about sustainability in the long term. We will, by definition, move to a sustainable energy supply. Think about it.

    Cheaper always wins…

    Nonsense. It’s cheaper to dump our garbage by the side of the road, but few people do. Or in other words, externalities.

    Ethics? It would be interesting if you could elaborate.

    It’s rather… surprising that someone like yourself so certain of the benefits of geoengineering and even proposing specific solutions hasn’t even heard of ethic concerns. But, no matter. Start here.

    https://www.nature.com/scitable/knowledge/library/geoengineering-and-environmental-ethics-80061230

  54. BBD says:

    Exactly. For example, one man’s geoengineering ‘success’ could easily be another’s crop failure and famine.

  55. izen says:

    @-Mircea Dochia

    Your enthusiasm for space may have led you to overlook easier and cheaper ground-based options for geo-engineering in responding to climate change. IIRC standard artillery can be used to put SOx into the stratosphere in imitation of a volcanic eruption.
    It is short term, but cheap and scalable.

  56. izen says:

    @-verytallguy
    “Nonsense. It’s cheaper to dump our garbage by the side of the road, but few people do.”

    In modern societies nearly everyone does dump their garbage by the side of the road. Usually in front of their residence once a week or fortnight. Collection is a social service because communal waste disposal is vastly more efficient than individual action and can be funded from property taxes.
    People who are not embedded in the society enough to pay the taxes, directly or indirectly, (travellers, shanty towns) to get the service, dump their garbage by the side of the road.

    I would be interested in a historical example of ethics and governance resulting in a useful response to a future social/material risk.

    Meanwhile…
    https://www.foxnews.com/science/carbon-dioxide-emissions-rise-in-2018-scientists-say
    “Carbon dioxide emissions across the world made their largest jump in the past year, rising an estimated 2.7 percent, according to three studies released Wednesday.”

  57. verytallguy says:

    “I would be interested in a historical example of ethics and governance resulting in a useful response to a future social/material risk.”

    https://www.theguardian.com/cities/2015/jul/30/kiruna-the-arctic-city-being-knocked-down-and-relocated-two-miles-away

  58. BBD says:

    I would be interested in a historical example of ethics and governance resulting in a useful response to a future social/material risk.

    I think the state pension scheme in the UK probably qualifies. It was started in 1908, so is historical.

  59. izen says:

    State Pensions and other welfare systems are reactive, responding to the social problems that have already arisen. Often as a side-effect of whatever the previous attempt was to address the problem.

    A mining firm knocking down a bit of a town that is in its way hardly seems ethical… even if they are offering to rebuild it next door.

    The Montreal Protocol on CFCs could be a candidate for a bit of ethical governance, although it was as much reactive as preventative.

    PRO-active ethical governance to prevent/adapt to a future problem is much less common than reactive governance of established or growing problems. And ethics seem to be an optional extra.

  60. Greg Robie says:

    @-Mircea Dochia, I plugged that 1% number into some rough reverse engineering calculations and 1% screening suggests that what I’ve crudely deducted from the Inuit elder’s observations point to a 30% error in solar incidence forcings in the climate models. I’m guessing such is significant … and could explain why observed Arctic ice loss is significantly out-pacing what the models present as plausible.

    So thanks!

    And, noting the bias for making space travel cheap, an understatement. Even just the 1% of screening adds up to something close to 650,000 square miles of effective shadowing. If located in a geostationary orbit, the preumbra effect of the shadow such an array would cast from 22,236 miles out would, and to produce an effective 1.3% screening be what? … A lot!

    In addition, if the models [can!] suggest a seasonally adjusted focus, of the share is required, a multiplier to compensate for the tilt of the planet’s axis would …

    Oh, … and then there’s [maintence]!

    And I would still appreciate critique of the quantifying effort I’ve attempted.

  61. BBD says:

    State Pensions and other welfare systems are reactive, responding to the social problems that have already arisen.

    In the same way that CO2 emissions reduction policy is reactive to issues arising already from >400ppm but *designed* to head off much worse problems in future?

  62. “So, no link to claims of exponential rises ”

    VTG, IPCC AR5 WG1 Figure 12.43,

    delivers 8.5 C of long term warming from 8.5 W/M2 of radiaive forcing

  63. verytallguy says:

    Nothing exponential there Russell. Switcheroo to “long term” noted.

    Triple down.

    Go Harvard!

  64. Greg Robie says:

    Share is is an auto corrected shading, and the request for review, my attempt to roughly quantify the Inuit observations. Thx … anyone.

  65. VTG, you’re starting to sound pythonesque:
    the 8.5 curve is concave in the here and now

  66. Dave_Geologist says:

    In fairness to Russell vtg, RCP8.5 and 6.0 have a bit of the negative exponential about them from the late 21st Century. Presumably the assumption is that by that stage, the shit has hit the fan so comprehensively that even the most ardent deniers and lukewarmers have flipped to “OMG, someone, please, do something!“.

    Although I doubt that’s what he had in mind.

  67. lerpo says:

    This also looks concave. Where’s the discrepancy?

  68. Clive Best says:

    RCPS use inverted logic. They are based on the resultant forcing in 2100 and then derive a concentration ‘pathway’. If C is the final CO2 concentration then to 1st order

    So 5.3ln(C/280) = 8.5/5.3

    or C = 280*4.972 = 1392 ppm !

  69. Clive,
    Yes, that is roughly how I understand it. The RCPs were largely set to produce certain changes in forcing by 2100. There are then a range of possible emission pathways, and social pathways, that could produce such concentration pathways.

  70. BBD says:

    1392 ppm !

    When someone can tell me we’ve nailed down the carbon cycle feedbacks, then we can be complacent about primary anthropogenic emission constraints on end-of-century ppm.

  71. The Very Reverend Jebediah Hypotenuse says:


    …then we can be complacent about primary anthropogenic emission constraints…

    Let’s see. How are we doing so far?

    CO2:
    We haven’t stopped CO2 growth, we haven’t even slowed it.

    CH4:
    There’s no sign of stopping or even slowing.

    N2O:
    Again, no sign that we’ve stopped increasing or even slowed down.

    All the evidence to date suggests that 1392 ppm is not only possible, it’s inevitable.

    Your move, carbon cycle feedbacks.

  72. verytallguy says:

    Russell,

    Your claim was “an immanent transition from linear to exponential temperature rise from anthropogenic forcing.”

    There’s no way you can seriously point to that chart and asset it supports such a statement. Neither did it have anything to do with Hansen.

    The twists and turns you’re undertaking are indeed Pythonesque.

  73. Willard says:

    > I personally think that even with small to medium reductions we’ll still eventually get there.

    I personally think personal beliefs are immaterial:

  74. The Very Reverend Jebediah Hypotenuse says:


    Neither did it have anything to do with Hansen.

    Yes – but Al Gore.

    Actually, although I can’t find Hansen opining on exponentials, a quick search reveals that he has recently noted that the rise in global mean temperatures may be departing from linear.


    Global temperature appearsto increase almost linearly over the past 50 years; the 1970 – present rate is 0.17 °C per decade. Jeremy Grantham pointed out that the rate of warming inferred by connecting the peak temperatures of the last two El Nino maxima (0.21 °C per decade, see figure above) exceeds this longer term rate, and he infers that global warming is accelerating. La Nina minima probably provide a better estimate, and they provide more recent rates. As the figure shows, the most recent two La Ninas imply a warming rate of 0.38 °C per decade, at least double the longer term rate! Such acceleration is predicted by climate models for continued high fossil fuel emissions as a result of amplifying climate feedbacks and is a cause for concern. We expect global temperature rise in the next few months to confirm our analysis.

    http://www.columbia.edu/~jeh1/mailings/2018/20181015_GlobalWarmingAcceleration.pdf

  75. Willard says:

    Zeke took a look at the various RCPs and concludes:

  76. izen says:

    @-ATTP
    “The RCPs were largely set to produce certain changes in forcing by 2100. There are then a range of possible emission pathways, and social pathways, that could produce such concentration pathways.”

    Do those emission pathways assume that the same ratio of emissions get shared into the land/ocean part of the Carbon cycle, halving the forcing impact, in the future ?

    Is the contribution from soil Carbon in permafrost peats, or ocean methane release as positive feedbacks assumed to be insignificant ?

    Are these assumptions any more credible than projected reductions in rates of emissions ?

    https://www.foxnews.com/politics/epa-announces-rollback-of-obama-era-coal-emissions-rule
    “The Environmental Protection Agency announced Thursday a plan to roll back Obama administration-era coal emissions standards.
    “By replacing onerous regulations with high, yet achievable, standards, we can continue America’s historic energy production, keep energy prices affordable, and encourage new investments in cutting-edge technology that can then be exported around the world,” “

  77. Sorry VTG, your signal to noise ratio has reached the Hellman Limit.

  78. verytallguy says:

    Russell, it’s been bizarre, truly.

  79. Everett F Sargent says:

    Well that image URL didn’t inline itself properly, so let’s try this one …

    Still :/

  80. Everett F Sargent says:

    AFAIK, the only way I get Kopp’s 42 number (versus 37.1) is to convert from metric tonnes (actually Imperial ton) to USA short tons (2240/2000 = 1.12) …
    37.1 * 1.12 = 41.552 (rounds up to 42) 😦

    LULC are already included in the Global Carbon Budget 2018

    Anyone else get 42 from 37.1?

  81. Everett F Sargent says:

    OK, found it, the Global Carbon Budget 2018 has LULC in a separate column from FF emissions. So OK with Kopp’s 42 through 2018. 🙂 Sorry, my bad.

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