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IPCC Special Report on 1.5ºC

Filed under: — gavin @ 7 October 2018

Responding to climate change is far more like a marathon than a sprint.

The IPCC 1.5ºC Special report (#SR15) has been released:

Thoughts

It’s well worth reading the SPM and FAQs before confidently pronouncing on the utility or impact of this report. The FAQs include the following questions:

  1. FAQ 1.1: Why are we talking about 1.5°C?
  2. FAQ 1.2: How close are we to 1.5°C?
  3. FAQ 2.1: What kind of pathways limit warming to 1.5°C and are we on track?
  4. FAQ 2.2: What do energy supply and demand have to do with limiting warming to 1.5°C?
  5. FAQ 3.1: What are the impacts of 1.5°C and 2°C of warming?
  6. FAQ 4.1: What transitions could enable limiting global warming to 1.5°C?
  7. FAQ 4.2: What are Carbon Dioxide Removal and negative emissions?
  8. FAQ 4.3: Why is adaptation important in a 1.5°C warmer world?
  9. FAQ 5.1: What are the connections between sustainable development and limiting global warming to 1.5°C?
  10. FAQ 5.2: What are the pathways to achieving poverty reduction and reducing inequalities while reaching the 1.5°C world?

First thing to remember is that this special report was commissioned from the UNFCCC on the back of the Paris Accord (which is not the process for main IPCC reports). Secondly, the IPCC is constrained to only assess published literature or otherwise publically available data. This means that if no groups have studied a question, there isn’t much to assess. Sometimes the gaps are apparent even in the scoping of the reports which can encourage people to focus on them at an early stage and have publications ready in time for the final report, but one of the main impacts of any of these reports is to influence research directions going forward.

What does 1.5ºC mean?

The SR15 has defined 1.5ºC as the warming from the period 1850-1900. This is 2.7ºF and about 1/3rd of an ice age unit (the amount of warming from the depths of the last ice age 20,000 years ago to the mid-19th Century).

This baseline is not really “pre-industrial”, and there have been some interesting discussions on what that phrase might be usefully defined as (Hawkins et al ,2017; Schurer et al, 2017), but this baseline is the easiest to adopt since estimates of climate impacts are being based on climate models from CMIP5 which effectively use that same baseline. The timing of projected impacts is a little sensitive to definitional issues with the “global mean” temperature, and whether the instrumental record is biased with respect to changes in the mean – particularly in the earlier part of the record when the data is relatively sparse.

At current rates, we’ll hit 1.5ºC on a decadal-average basis by ~2040. The first year above 1.5ºC will occur substantially earlier, likely associated with a big El Niño event in the late 2020s/early 2030s.

Can we avoid going through 1.5ºC?

IPCC has to use a few circumlocutions to avoid giving a direct answer to this question (for reasonable and understandable reasons). I’m not quite so constrained…

There are many issues related to the feasibility question of which physical climate-related issues are only one. The basic issue is that the effort to reduce emissions sufficiently to never get past 1.5ºC would require a global effort to decarbonize starting immediately that would dwarf current efforts or pledges. This seems unlikely (IMO).

There are a few ‘get-out-of-jail’ cards that are considered. First, we can overshoot 1.5ºC, and then come back down after heroic efforts to reduce CO2 levels in the atmosphere though so-called ‘negative emissions’. This makes the immediate task less daunting, but at the expense of relying on global scale efforts with carbon sequestration, or BECCS, or direct air capture, which are extremely speculative. Second, we could start direct geo-engineering efforts to reduce temperatures and (most optimistically) buy time for carbon emissions to come down a little more slowly. Both of these scenarios come with dramatic and underexplored geo-political consequences (are there any stable governance regimes for geo-engineering? is there sufficient land for large scale BECCS?), as well as substantial moral hazard.

So my answer is… no.

I get that there is reluctance to say this publically – it sounds as if one is complicit in the impacts that will occur above 1.5ºC, but it seems to me that tractable challenges are more motivating than impossible (or extremely unfeasible) ones – I would be happy to be proven wrong on this though.

The utility of the SR15 report?

Even if you think that working on responses to impacts that are almost certainly going to be smaller than we are actually going to see, there are some useful aspects of this report. The basic fact is that moving beyond the small efforts that have been made so far implies transitions that are effectively the same whether we hope to stabilise at 1.5ºC, 2ºC or even 3ºC – only the rate at which they are implemented differs.

This is because near-term reductions in carbon emissions by ~70% are required to even stabilize CO2, and to stabilize temperature, even further (net) reductions are required. And worse still to stabilize sea level, eventual temperature drops would be required.

Efforts on these scales are not easy, and will need to be sustained over many decades and much of the work discussed in this report will be central to that. Nonetheless, this will be a marathon effort. It is thus perhaps worth paraphrasing Eliud Kipchoge, the recent winner of the Berlin marathon:

The best time to start [reducing emissions] was 25 years ago. The second best time is today.

References

  1. E. Hawkins, P. Ortega, E. Suckling, A. Schurer, G. Hegerl, P. Jones, M. Joshi, T.J. Osborn, V. Masson-Delmotte, J. Mignot, P. Thorne, and G.J. van Oldenborgh, "Estimating Changes in Global Temperature since the Preindustrial Period", Bulletin of the American Meteorological Society, vol. 98, pp. 1841-1856, 2017. http://dx.doi.org/10.1175/BAMS-D-16-0007.1
  2. A.P. Schurer, M.E. Mann, E. Hawkins, S.F.B. Tett, and G.C. Hegerl, "Importance of the pre-industrial baseline for likelihood of exceeding Paris goals", Nature Climate Change, vol. 7, pp. 563-567, 2017. http://dx.doi.org/10.1038/nclimate3345

94 Responses to “IPCC Special Report on 1.5ºC”

  1. 1
    J4Zonian says:

    Typo?

    “Even if you think that working on responses to impacts that are almost certainly going to be smaller than we are actually going to see [IS POINTLESS], there are some useful aspects of this report.”

  2. 2
    Killian says:

    I said 2C was disaster 8 to 10 years ago. I say 1.5C is now. Nothing has changed eexcept you understand, almost, what I said then. But not quite. 1.5C makes 2C possible makes 3C possible makes…

    For nearly 3 million years not over 300ppm. Anything else is extremely poor risk management.

    The numbers have been wrong. The policies worse. This only improves that in a less-bad sense.

    Nature says 300. I find she never lies.

    Besides, 260ppm is simple. It won’t be easy. But why risk anything else?

  3. 3
    Kip Diskin says:

    Is the masking effect of aerosols, which is estimated to be anywhere between 0.2 and 0.5 C, considered in these projections?

    [Response: yes. The projections include short-lived components (aerosols, CH4, ozone etc.) and take into account both the warming and cooling effects. The most optimistic scenarios include big cuts in CH4, and ozone precursors in addition to CO2 emissions and include consequent aerosol changes that while they don’t go in the ‘right’ direction are more than made up for. – gavin]

  4. 4
    Keri says:

    Do you know why the 2006-2015 is used to assess the remaining budget instead of recent températures ?
    Because if I take “your” data, Gavin, 2010-2018 is 0,1°C warmer than 2006-2015, and 2015-2017 is 0,26°C warmer.
    IPCC gives 0,63°C to go to 1,5°C while most recent NASA Giss temperature would let only 0,37°C. That would change the budget.

  5. 5
    Fred Mayer says:

    I did some calculations on this using the greenhouse gas law and the IPCC range for ECS.
    As far as I can see there is a very real danger that we are already committed to 1.5C even at current CO2 concentrations.

    We are currently at about 410ppm CO2, and the IPCC suggest a range for ECS between 1.5C and 4.5C.

    ΔT = α.ln(C1/C0)
    Substituting for ECS gives:
    ECS = α.ln(2)
    => α = ECS/ln(2)
    Now we can eliminate the unknown α from the equation, giving:
    ΔT = (ECS/ln(2)).ln(C1/C0)

    For ECS = 1.5C
    ΔT = (1.5/ln(2)).ln(410/280) = 0.85C
    Given that we have already seen 1C of warming, it appears that ECS is probably greater than 1.5C.

    For ECS = 3C
    ΔT = (3/ln(2)).ln(410/280) = 1.65C
    If ECS is 3C, we are already committed to over 1.5C of warming.

    For ECS = 4.5C
    ΔT = (4.5/ln(2)).ln(410/280) = 2.48C
    If ECS is 4.5C, we are already committed to over 2C of warming.

    There is no guarantee that we can achieve Paris at all even at current CO2 levels.

  6. 6
    Mark Brandon says:

    Tedious point I’m afraid. 2nd ref is wrong. You have it is Mann et al, it’s Schurer et al.

    [Response: oops!]

  7. 7
    Esko says:

    Kip Diskin
    Isn’t the cooling effect of aerosols most likely more that 0,5ºC ?
    “Removing aerosols induces a global mean surface heating of 0.5–1.1°C”
    https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2017GL076079

  8. 8
    Robert Cormia says:

    Instead of focusing (solely) on temperature, the build-up of heat in the ocean is of even more concern – https://www.nodc.noaa.gov/OC5/3M_HEAT_CONTENT/ Half the heat build-up in the ocean has occurred in the last ~ 25 years. See “Industrial-era global ocean heat uptake doubles in recent decades” Nature (2016). Heat up take by the world ocean is now ~ 10^22 J (10 zetajoules) per year. Global warming occurs in the ocean, climate change occurs when that heat is transferred to the atmosphere (latent and sensible heat) which we observe as the temperature anomaly. The build-up of ocean heat is the key metric to watch in projecting both temperature increases, and Sea Level Rise (SLR).

  9. 9
    Mal Adapted says:

    Thank you for a most excellent post, Gavin.

    This baseline is not really “pre-industrial”, and there have been some interesting discussions on what that phrase might be usefully defined as (Hawkins et al ,2017; Mann et al, 2017), but this baseline is the easiest to adopt since estimates of climate impacts are being based on climate models from CMIP5 which effectively use that same baseline.

    That clears up some confusion I’ve had.

    The basic issue is that the effort to reduce emissions sufficiently to never get past 1.5ºC would require a global effort to decarbonize starting immediately that would dwarf current efforts or pledges. This seems unlikely (IMO).

    I get that there is reluctance to say this publically – it sounds as if one is complicit in the impacts that will occur above 1.5ºC, but it seems to me that tractable challenges are more motivating than impossible (or extremely unfeasible) ones – I would be happy to be proven wrong on this though.

    AFAICT, only motivated AGW-deniers think it sounds like you’re complicit in the impacts of greater warming. I, for one, very much appreciate your candor.

    The basic fact is that moving beyond the small efforts that have been made so far implies transitions that are effectively the same whether we hope to stabilise at 1.5ºC, 2ºC or even 3ºC – only the rate at which they are implemented differs.

    Yes, and if we are to stabilize at any GMST intentionally, some things tried so far, e.g. carbon taxes, need to be scaled up to national level. Still, small efforts are more tractable than larger ones, thus more motivating, as you point out. I expect multiple smaller-scale (i.e. polycentric) collective efforts to grow and spread, potentially adding up to meaningful aggregate emissions reduction in the next few decades. We won’t have to wait long to find out! I’m personally looking ahead to around 2050, with mixed anticipation and trepidation.

  10. 10
  11. 11

    Fred (#5),
    It’s worth looking at this Realclimate post and this paper. If we get emissions to ~zero, then atmospheric concentrations will actually drop so that our committed warming is closer to the transient response at the time at which emissions cease, not the equilibrium response. So, if we can get emissions to ~zero before we cross the 1.5C threshold, then we can keep warming close to, or even below, 1.5C. There are some complexities related to aerosols and short-lived greenhouse gases, but the key point is that our committed warming is not the equilibrium response to our current atmospheric CO2 concentration, it is closer to the transient response. The real inertia is societal/political.

  12. 12
    MA Rodger says:

    Zeke Hausfather has an interesting piece at CarbonBrief explaining how/why the Carbon Budgets of #SR15 differ from those set out in IPCC AR5.

  13. 13
    Russell says:

    Those celebrating the Nordhaus Nobel should note the Economics prize also went to Paul Romer of NYU, for demolishing the foundations of Limits To Growth economics:

    It cannot please The Club of Rome that the Nobel Committee notes Romer:

    “showed that growth driven by the accumulation of ideas, unlike growth driven by the accumulation of physical capital, does not have to experience decreasing returns. In other words, ideas-driven growth can be sustained over time.”

  14. 14
    Kip Diskin says:

    @Gavin, @Esko

    I have indeed seen higher estimates of the aerosol masking effect than the one I mentioned, but I seem to always get ‘set straight’ for bringing them up because the uncertainty of the strength of the effect is deemed so high.

    But maybe Gavin can shine a light on this. If the lower end of the estimate is indeed 0.5 C, how can it be true that this cooling effect is taken into consideration when discussing a goal of 1.5 degrees of warming? Shouldn’t we be talking about 2 C or even 2.5 C?

    This especially, since there is also a 20 to 25 year lag before we would reach equilibrium of the global mean temperature if CO² concentrations would remain stable.

    Thanks in advance for any clarification on this point.

    -Kip

  15. 15

    Thanks for a really important post–both the links to the various documents and the independent commentary.

    The conclusion that we can’t (realistically) avoid going through 1.5 C is not cheerful, but hardly surprising for any of us who’ve been paying attention.

    I’m going to take some time with the documents before commenting further. As usual, they are densely written and really take some thought–and I haven’t even got to the main report yet.

  16. 16
    Gary Latshaw says:

    If one large political entity – a large country (>10 million) or even a large state (such as CA) (pop>10 million) sets on a path to achieve these goals or better, that could serve as a game-changer for the others. Norway has ambitious goals, but has the unique advantage of abundant hydropower, which cannot be duplicated elsewhere.

  17. 17
    SecularAnimist says:

    Gavin wrote: “The basic issue is that the effort to reduce emissions sufficiently to never get past 1.5ºC would require a global effort to decarbonize starting immediately that would dwarf current efforts or pledges. This seems unlikely (IMO).”

    In short, we could do it. But we will probably choose not to.

  18. 18

    Killian: I am not familiar with your work or earlier statements regarding 2 degrees, etc. Could you provide some pointers or links? Especially interested in learning why you think 260 ppm is easy. Not saying it isn’t, but curious what approaches can get us there.

  19. 19
    John says:

    Meanwhile, all the thunder is being stolen by denier John McLean and his story about how 70 errors in hadCRUT4 has invalidated everything. Pity nobody is debunking this yet.

  20. 20
    Chris G says:

    I think the origin of the quote is older than Eliud; I heard it was a Chinese proverb maybe 10 or more years ago. I used it in climate change talks about 8 years ago.

    Echoing other sentiments, if you guess that it will take ~20 years to replace our fossil fuel energy production infrastructure even after we get serious about trying, and there is maybe 0.7 C degrees of warming to which we are already committed, it’s hard to be optimistic. Nevertheless, having a wreck at 20 mph does not do nearly as much damage as one at 75 mph.

  21. 21
    Mike MacCracken says:

    What worries me much more than the exact temperature change is the potential equilibrium sea level rise. Drawing from paleoclimatic reconstructions, global sea level at the last glacial maximum was down 120 meters when the global average temperature was down roughly 6 C; at the Eemian, perhaps 1 C over preindustrial for several thousand years, sea level was up 4-8 m or so; go back a few tens of million years, and there were virtually no Greenland or Antarctic ice sheets (so maybe 70 m of SL equivalent) when the world was 4 C warmer. It would seem that the equilibrium sea level sensitivity to global average temperature is of order 15-20 meters per degree C. From 20ka to 8ka, SL rose on average a meter per century for 120 centuries while the global average temperature was rising on average a degree C per 2000 years. With aggressive action, we’ll have gone up of order 2 C in 2 centuries, so 40 times faster than coming out of the last glacial period. Models have suggested time to equilibrium of perhaps several thousand years when not allowing for glacial movement–likely good bit less with movement. Moving toward a rate of SL rise of a few meters per century is not at all implausible and would cause disastrous impacts, and paleoclimate record makes clear ice goes away a lot faster than it builds up. Even staying under 1.5 C will be disastrous, and if we overshoot, this melt is not likely reversible except over very long times. In my view, we’ve all been using the global average temperature as the metric to focus on–the potential for sea level rise makes much more clear how serious the situation is that we are in. I’d suggest IPCC’s report is far too sanguine.

  22. 22
    Tony Weddle says:

    You say we’ll get to 1.5C by about 2040, earlier on an individual year basis. Michael Mann estimated that we’d get to 2C by 2036, in his Scientific American article, more than 4 years ago. What are the differences between these two estimates? I don’t think much has changed to BAU, in the intervening 4.5 years.

    In that article, he also estimated that CO2 levels must not exceed 405ppm to avoid 2C of warming at all. I think that is about the average level now in the atmosphere, without accouting for CO2 equivalence of other GHGs. This does all depend on an ECS of 3C, though. Is that the reason for the difference?

  23. 23
    Carrie says:

    SR15 SPM
    A3. Climate-related risks for natural and human systems are higher for global warming of 1.5°C than at present, but lower than at 2°C (high confidence).

    Well the time it took to read those 33 pages I will never get back. What a waste of time, energy and money. Dear IPCC, thanks for nothing. What’s the main prognosis? Net Zero GHG emissions by 2050. As if this wasn’t known 10 to 20 years ago already? A sane rational humanity would set it by 2040.

    @1.5C a summer ice free arctic might happen once per century? They’re dreaming and underestimating the impacts of global warming and climate change significantly. There will a summer arctic sea ice free ocean there long before it hits +1.5C and most likely before 2030.

    The headline statements are no better. I get this report was written for the UNFCCC bureaucrats and scientific /academic heads. Ye they do make it public. For politicians, journalists and the public no part of this report is fit for purpose. The wording and semantics is atrocious. They never articulate what a ‘statement’ or a ‘clause’ means as far as consequences, relationships, significance in the real world to any individual. Broadly the report totally fails to communicate “meaning or understanding” to everyday normal human beings or politicians.

    Couldn’t these scientists, the IPCC or the UNFCCC afford to hire a decent writer who could present the hard data points into a proper comprehensible story filled with ethical meaning from the readers perspective?

    A real description of challenges and the social changes to be done … like spell it out in away people can understand and relate to?

    Besides that as usual it appears on the surface to again being extremely conservative in it’s prognostications. eg keeping at 1.5C vs 2C will reduce SLR to 2100 by 0.1 Meters? They can’t be serious.

    Why not cut the crap and just publish a headline telling commerce and industry that working to keep it to 1.5C will make no significance difference at all?

    To be honest this SPM reads like pure fantasy. Another waste of everyone’s time, those who wrote it and those who read it or read about it in the news media.

    As a piece of communication I rate this report 0/10.

    Useless and ineffective.

  24. 24
    Carrie says:

    What the world needs is not another report. What it desperately needs is some global Leadership that will shake the tree of lethargy into one of serious radical action to upend the current economic system and geopolitical order.

    A global leadership team with the qualities of Martin Luther King, of Jack and Bobbie Kennedy, like a Reagan and a Thatcher could move people, a Gorbachev figure with an inspiring giant of a man like Nelson Mandela. A MalcolmX and a Ho Chi Minn. A Winston Churchill and Queen Mary. A Mahatma Ghandi or ten of them!

    People who can speak clearly, convey meaning and move people to both understand and accept massive change in priorities and goals and personal ambitions, iow a real individual sacrifice is required. A reorientation of our individual and collective idealism toward rapid serious effective action globally and nationally for the good of all and of The Commons we only hold in Trust for our future generations.

    Either we wake from this illusion or we commit collective suicide.

  25. 25
    Keith Woollard says:

    This is what happens when you get scientific bodies trying to foresee the future:-
    https://www.smh.com.au/national/8-a-litre-tipped-for-2018-20080710-3d6w.html

  26. 26
    Geoff Beacon says:

    Mal-adapted. Yes,

    Thank you for a most excellent post, Gavin.

    Keri,

    IPCC gives 0,63°C to go to 1,5°C

    That “0.63°C” in sr15_chapter1_annex.pdf reminded me of the Millar et. al paper that caused so much controversy last year. It’s use of the HADCRUT4 temperature measure (which excludes the fast warming Arctic), was criticised – as well as its choice of starting time for pre-industrial. Myles Allen was one of the co-authors with Richard Millar.

    The Coordinating Lead Authors for Chapter 1 were:

    Myles Allen (UK) – “Head of the Climate Dynamics group”.
    Opha Pauline Dube (Botswana) – Research: “Geography and Remote Sensing”
    William Solecki (USA) – Research: “Urban environmental change”

    It seems the climate science in Chapter 1 is guided by Professor Allen.

    In addition the Chapter Scientist to Chapter 1: Framing and Context was Richard Millar.

    Without questioning their sincerity, it is worth wondering if Allen and Millar, are at the ‘softer’ end of the spectrum of the views among climate scientists.

    Having said that, I congratulate the authors of this report. It has raised the awareness of a largely ignorant public.

  27. 27
    Serrara says:

    https://www.reddit.com/r/collapse/comments/9mnwte/five_steps_to_15_c_bullshit/

    Seeing this post getting thrown around across some Reddit comment threads…are these coherent facts? Curious…

  28. 28
    A real scientist says:

    “Limiting global warming to 1.5ºC would require rapid, far reaching and unprecedented changes in all aspects of society”

    Which is why 1.5C is the new target. Climateschatology is indistinguishable from its non-climate namesake. Armageddon is always a decade away and always requires fundamental changes in our behavior to avert. The only difference is the “scientists” peddling climateschatology are better paid, fed and washed than the homeless guy shouting on the street corner.

  29. 29
    Geoff Beacon says:

    Robert Cormia #8

    Instead of focusing (solely) on temperature, the build-up of heat in the ocean is of even more concern.

    Yes, Ocean Heat Content should concern the Small Island Developing States. Were they cheated by a change in the meaning of a 1.5C temperature rise?

    I suspect so.

  30. 30
    David Hallowes says:

    The IPCC fund an extra 300 Gt in the carbon budget (foot note 14). Any comment on how they did that and if we should believe it?

  31. 31
    John Archer says:

    The grass in my garden is only just starting to recover from the blistering attack of climate change this year.

    I’ve put charcoal on it to attract the carbon in CO₂ to help it grow. Do you think this will work?

  32. 32
    Donald Morton says:

    Does this new report anywhere deal with the important question of the ratio of natural and anthropogenic contributions to a rising global temperatutre. IPCC2013 states, “It is extremely likely that more than half of the observed increase in the global average surface temperature fro 1951 to 2010 was caused by the anthropogenic increase in greenhouse gas concentrations and other anthropogenic forcings together”. This is not very helpful in deciding on the relative efforts to direct toward adaptation vs. mitigation. If there is a large natural component, many mitigation efforts will be less effective than assumed.

  33. 33
  34. 34
    Carrie says:

    Having now looked at some of the detailed pages the Summary is fairly accurate. I never said it wasn’t above. From a high brow academic perspective the announcements and the SR15 SPM are reflective of the work upon which they are based, being the source Papers and the report in detail.

    So from a scientific rigor perspective it’s good fair and accurate. Those high brow bureaucrats in the UNFCCC and the various Governments “experts” who will screen this report of their own Governments (be they pro-con rational climate action) will have substantial credible scientific based “evidence” to make their arguments – be they pro or con arguments – the evidence is in the detailed sections of the SR15 report.

    Even I can understand much of the basis for this report and comprehend what the SPM is saying, why and what it generally means and speaks to.

    My rating for it’s communication to the average Politician/policy maker who has a vote, the political parties of the world, the journalists and the voters including most “professionals” with Uni Degrees the SPM gets a 0/10 rating as being useless.

    I know it’s hard and reactions are tough to manage but please do note the difference between values about scientific accuracy and literacy versus the people I am speaking FOR here who need to understand in the fullest sense what this Report means and is really saying to them but cannot.

    The UNFCCC is only as good as the Governments elected who then send their representatives to the UNFCCC deliberations. Because of this it doesn’t really matter what the science says in the SR15. The scientists don’t get to decide what to do about it.

    Nothing will come of this Report nor the AR6 either. By 2040 there won’t even be an UNFCCC or IPCC except ion some people’s memory. imho.

  35. 35
    Nemesis says:

    1.5°C? No comment.

  36. 36
    Nemesis says:

    @Sir Gavin Schmidt

    Thank you for your honest statement about 1.5°C. Beside that you are one of the coolest climate scientists ever.

  37. 37
    Nemesis says:

    @Charlie, #10

    Thanks for that wonderful piece of Jazz-Music 8=)

  38. 38
    Carrie says:

    That’ll be my Epilogue, if you will, for I still quit and turn my back on this ‘issue’ and the waste of words that it has and will always be for all.

  39. 39
    Jim Eager says:

    “A real scientist says….”

    I seriously doubt the claim.

  40. 40
    Mal Adapted says:

    Mark Brandon:

    Tedious point I’m afraid. 2nd ref is wrong. You have it is Mann et al, it’s Schurer et al.

    [Response: oops!]

    Heh. “Pal review” ;^)?

  41. 41
    Radge Havers says:

    Well, I don’t know about 0/10, but the “Cumulative Emissions of CO2…” graph has some problems. It’s attractive, I’ll give you that, but it illustrates some basic bad habits and the trickiness of using color effectively.

    Graphic Literacy. It’s a thing. I mean, I know this is a sophisticated bunch here, but perhaps it would be a good idea to practice making graphics that aren’t elliptical for the non-scientist.

    Anybody think they see what I might think I think I could be seeing that other people should maybe be seeing but maybe still other people think is not an issue worth seeing?

  42. 42

    JA, #16–

    I’ve put charcoal on it to attract the carbon in CO₂ to help it grow. Do you think this will work?

    Um, charcoal is carbon… for starters…

  43. 43
    Donald Condliffe says:

    Unfortunately this report is an exercise in rearranging the deck chairs on the Titanic. The scientific analysis is very sound,but this is not a scientific problem, it is a political and economic problem. It reminds me of the old joke about opening a can of food without a can opener and the economist’s solution is “lets assume we have a can opener.”

    Now we have the scientists saying “lets assume we stop burning fossil fuels.”

  44. 44
    Tony Weddle says:

    Just heard Michael Mann being interviewed on this. As I mentioned above, he thinks we’ve warmed more than the report says and so are closer to 1.5 already. He didn’t actually mention what he thought the real figure was but did reiterate his SciAm article about the northern hemisphere likely to reach 2C in the late 2030s.

    He played a kind of good cop/bad cop near the end by giving the impression that we could still avoid dangerous warming by acting positively. However, he used a phrase something like “we can avoid the worst impacts of warming by…” but without defining what “worst impacts” mean. If he’s reading, here, could he define it, please? One could imagine that the worst impact is Hothouse Earth, but shouldn’t we try to avoid something a lot less than that?

  45. 45
    Killian says:

    Re #18 Gary Rucinski said Killian: I am not familiar with your work or earlier statements regarding 2 degrees, etc. Could you provide some pointers or links? Especially interested in learning why you think 260 ppm is easy. Not saying it isn’t, but curious what approaches can get us there.

    Actually, I said simple, not easy. Major transitions are hard, but transitioning from extreme complexity and fragility to simplicity and antifragility should be far easier than the other way around. Grow a garden, capture water, use natural energy, build community. Mostly stop doing all the things not based on meeting needs, with some specific exceptions.

    That’s just a very rough outline of the types of changes; the hows and whys are bit more involved. More later.

    Thanks for asking.

  46. 46
    Killian says:

    Re #13 Russell said Those celebrating the Nordhaus Nobel should note the Economics prize also went to Paul Romer of NYU, for demolishing the foundations of Limits To Growth economics:

    It cannot please The Club of Rome that the Nobel Committee notes Romer:

    “showed that growth driven by the accumulation of ideas, unlike growth driven by the accumulation of physical capital, does not have to experience decreasing returns. In other words, ideas-driven growth can be sustained over time.”

    I think you may not understand Limits to Growth. The problem may lie with the idea of growth. Increases and improvements in deas should not be described as growth. An idea is a thought, not a physical action. LtoG did not propose thinking had limits, so I do not understand your statement at all.

    That said, it *does* follow that any “cool” new thing thought up may well be built by someone, and that gets to resources. Those have limits. Romer, essentially, if your statements are accurate, is a bit of a fool, imo, *if* he thinks ideas and production can be completely unlinked. It’s a dangerous proposition in a world considered to be on the verge of self-destruction. The same is true of “smart growth” and “green growth” and “sustainable development.” All these terms are attempted workarounds to limits, and they are B.S. efforts to pretend the previously-mentioned delinking is possible.

    But, hey, economics is voodoo, so…

  47. 47
    Victor says:

    “UNITED NATIONS (AP) _ A senior U.N. environmental official says entire nations could be wiped off the face of the Earth by rising sea levels if the global warming trend is not reversed by the year 2000.

    Coastal flooding and crop failures would create an exodus of ″eco- refugees,′ ′ threatening political chaos, said Noel Brown, director of the New York office of the U.N. Environment Program, or UNEP.

    He said governments have a 10-year window of opportunity to solve the greenhouse effect before it goes beyond human control.

    As the warming melts polar icecaps, ocean levels will rise by up to three feet, enough to cover the Maldives and other flat island nations, Brown told The Associated Press in an interview on Wednesday.

    Coastal regions will be inundated; one-sixth of Bangladesh could be flooded, displacing a fourth of its 90 million people. A fifth of Egypt’s arable land in the Nile Delta would be flooded, cutting off its food supply, according to a joint UNEP and U.S. Environmental Protection Agency study.” ETC.

    Sound familiar? It’s from an article dated June 29, 1989: https://www.apnews.com/bd45c372caf118ec99964ea547880cd0

    Oh and by the way, the Maldives are doing fine:

    https://maldivesfinest.com/saudi-arabia-to-invest-10bn

    https://theodora.com/wfbcurrent/maldives/maldives_economy.html

  48. 48
    Karsten V. Johansen says:

    It’s common to use the phrase “we have to do” this or that about mankind. Problem: all historical evidence points to the fact that there is no “we” there. Today there is about twenty-thirty or even less so called human beings controlling more than half the global fortune and these superoligarchs are dictating the fate of the rest for all practical purposes. As long as this is the situation, nothing whatsoever is going to change mankind’s course from the present catastrophic direction, not the warming, not the plastic pollution of the sea, not the acidification of the sea, not the depletion of the phosphorous resources etc. etc. If anything the complete practical political ignorance of all real problems here mentioned and almost any other real problem by all “powerful” “leading” politicians shows us that we are on a supersteady course to Hell. As long as only very few dare even mention this, of course nothing is going to change. I respect the idealistic and restless work being done by all scientists despite the fact that most of them recognize the real catastrophic situation. But as long as they continue to downplay the really extremely desperate political situation, nothing is going to change. Only James Hansen has here taken another direction with his proposal “carbon fee and dividend”, since 2008 functioning in a somewhat lame form in British Columbia, but at least working. Already november 2015 he called the Paris “agreement” (what is a not – binding agreement? No agreement at all…) what anyone can see it is now: “pure bullshit”. This is the language the scientists need to talk load and clear. Still more bullshit is only going to further strengthen the trumpists everywhere.

  49. 49

    Robert Cormia #8 http://www.realclimate.org/index.php/archives/2018/10/ipcc-special-report-on-1-5oc/#comment-711100 – beat me to it.

    Surface temperature is a direct indicator of the level of warming but it is not what drives massive storms, for example.

    Do we have enough data yet on the effect of increased ocean heat content on storms to make a statement about the number and strength of hurricanes in the last year? Possibly…

    Trenberth, K. E., Cheng, L., Jacobs, P., Zhang, Y., & Fasullo, J. (2018). Hurricane Harvey links to ocean heat content and climate change adaptation.
    Earth’s Future, 6. https://doi.org/10.1029/2018EF000825http://www.cgd.ucar.edu/staff/trenbert/trenberth.pdf/2018_Trenberth_et_al-Earths_Future.pdf

  50. 50

    #43 Donald Condliffe http://www.realclimate.org/index.php/archives/2018/10/ipcc-special-report-on-1-5oc/#comment-711185

    Not comparable. Your economist assumes a prerequisite. Stopping burning fossil fuels is an option (in fact, the only one – and in the long run, we would anyway when they run out). Problem is: the “long run” could be long after we have wrecked the climate for sustaining human life on a large scale.

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