RealClimate logo


Unforced variations: Oct 2015

Filed under: — group @ 2 October 2015

This month’s open thread. Since most climate related discussion this month will be focussed on the COP21

What is (or should be) the role of climate science in the upcoming negotiations? Discuss.

201 Responses to “Unforced variations: Oct 2015”

  1. 1
    Russsell says:

    Those headed for the Paris COP should try to remember how many went riding for a a fall on the road to Copenhagen.

  2. 2
    Digby Scorgie says:

    COP21 Paris 2015

    If the Paris conference is a success, we shall see a slowing in the rate of increase of atmospheric carbon dioxide followed, after some years, by the beginning of a long, slow decline. On the other hand, if there is little change in the rate of increase, we shall know that the conference was a failure.

    There are several actions that can contribute to a successful outcome at Paris. By far the most significant, however, will be an immediate and continuing decline in the burning of fossil fuel. With no curbs on fossil fuel, the result will still be failure even if all other possible actions are implemented. Indeed, continuing to burn fossil fuel is sufficient all on its own to precipitate catastrophe.

    A decline in the burning of fossil fuel implies a commensurate decline in the production of the fuel. It follows that a successful outcome at Paris will be manifested by an immediate and continuing decline in the production of such fuel. And, in a related action, there will be an immediate cessation of searches for new sources of the fuel.

    Contribution of climate scientists
    Therefore, what climate scientists need to provide is information regarding the required magnitude of annual cuts in fossil-fuel production and the period for which these production cuts must be sustained. Constraints are the allowable final amount of warming, the probability of attaining this goal, and the minimum production rate permitted, if any, at the end of the mandated period. Distribution of declining supplies of fossil fuel between rich and poor nations is a separate political problem.

    The above information might well be available already, of course. All I can say is that I’ve never seen anything of the sort. What I envisage is a statement on the following lines:

    “To achieve no more than two degrees of warming with a probability of 50%, and assuming minimal reduction in other sources of carbon dioxide, the production of fossil fuel must be cut every year by an amount equal to 4% of 2015 production, beginning in 2016 and continuing for the next 24 years.”

    What have I got wrong?

  3. 3
    Leslie Graham says:

    http://pubs.acs.org/doi/full/10.1021/acs.est.5b02388

    Can someone explain in English what this new paper is is actualy saying?
    Thanks
    Back to lurking.

    [Response: All they are saying is that there is an accounted for source of isoprene into the atmosphere that hasn’t been included in global models yet. Isoprene is an ozone precursor, and source for secondary organic aerosols and has a small net cooling effect on the surface temperature. However, since this is a climatological input (not one that is changing substantially through time), it will only affect the background composition of the atmosphere, not any of the trends over time. So while it’s good news for helping get atmospheric chemistry right, it isn’t going to have any impact on climate change. – gavin]

  4. 4

    Victor 240 last month’s thread: #227 BPL, with all due respect, your paper is concerned with predicting the future (always a dicey effort) while the Sheffield paper evaluates what’s happened in the past. Also, I’m sorry but a couple sentences expressing disagreement over a technical issue is hardly a refutation.

    BPL: My analysis of PAST data (1948-2010, N = 63) shows that there is a very significant upward trend, and what’s more, it’s accelerating. Sheffield et al. were wrong. Deal with it.

  5. 5
    Ken Lassman says:

    So I’m curious: where does the stated EPA goal of reducing carbon emissions by 32% from 2005 levels and the Chinese agreement to cap emissions by 2020 and begin a cap and trade program to reach these goals put the planet in relation to the 2 degrees Celsius limits by 2100? What limits would the rest of the world have to place on emissions to have a reasonable chance of achieving this goal?

    Another way to pose the question: which RCP trajectory are we closest to being on if the US and China cuts lead the way to similar cuts by other countries?

    Simple questions with complex answers, but I’m curious as to where the political realities place us on these trajectories.

  6. 6
    Ken Lassman says:

    I’m curious about where the EPA Clean Power Plan goal of reducing emissions 32% from 2005 levels, coupled with recent agreements by India and China to reduce/cap emissions/set up a cap and trade program places the planet, assuming that other countries follow the lead and do similar cuts. Do these goals make it possible to achieve the under 2 degrees Celsius by 2100 goal? Anyone seen/done a credible analysis?

    Put another way, where do these cuts most likely put us on the RCP pathways? Last time I looked it seemed we were still on the Business-as-usual 8.5 RCP trajectory. Do these proposals credibly bump us off that trajectory, and if so, how far?

  7. 7
    Killian says:

    I’m not sure what “role” really means here. The role is defined: Determine what the frack is going on. I think that has largely been done in so far as the risk has been so great for so long already that any further info really is superfluous in terms of policy. (Don’t bother disagreeing with this point, peanut gallery, it’s based heavily on what sustainable systems are like, and on that few, if any of you, will agree with me, so the point is moot for the purposes of this discussion.)

    What is left to do that could greatly impact COP21 is to tie risk better to the science. I do not mean the error bars in the data, rather the risk assessment in terms of long and fat tail effects. The public and policymakers do not seem to grasp the severity and certainty of the risk. The fact that the longest part of the tail is where policy should be pointed to is not coming through. The depth and breadth of needed changes are glossed over in virtually every case but for a relatively few voices, even still.

    Part of this is messaging, such as the use of modal verbs in discussing what are actually certain future events. “Miami may be underwater…” No, Miami WILL be underwater no matter what we do. That’s already a given. E.g.

    I believe scientists can help with making the science visceral for policymakers and public by stepping just a little outside their reticence and traditional roles as scientists by speaking to risk in more secular, policy-based terms.

    I think a scientist saying at COP21 that, e.g., Miami and NO are already Dead Men Walking, so what are you going to do about it, policymakers? might significantly help move the needle.

    Is there consensus on, e.g., the rate and extent of WAIS destabilization and collapse? No. But isn’t the possibility, thus the risk, on the order of we might lose the whole damned thing over time frame T? Isn’t it possible, given the other thousands of uncertainties, that whatever the rate ends up being we will not be able to adequately respond? Thus, shouldn’t a scientist say, unequivocally, if policy is not altered quickly enough we stand a greater than trivial chance of not being able to handle the effects of SLR, potentially disrupting global socio-politics to a degree of global chaos? Is that not a real risk, with billions of refugees possible when all cliamte effects are included?

    You asked….

  8. 8
    Bob Johnson says:

    To clarify that we can’t predict the future 100%, but that climate science is about making risk assessments so that the policy makers can make the proper risk management. To stress that climate science is fully falsible, even though it’s about risk assessment and not about absolute predictions – and that the politicians have to act on that basis. Take a look at the discussion here: http://www.climate-debate.com/forum/there-is-still-no-global-warming-science–d10-e507.php

  9. 9
    patrick says:

    Thank you for this most relevant topic. Climate science should keep the talks on track without compromise or distraction. The track is climate and anthropogenic warming.

    Degree of confidence about projections of the effects of using fossil fuels–or, conversely, of cutting them up front–should be distinguished continually from degree of confidence about putting after-burners, so to speak, on business as usual.

    What science should do at the talks is exactly modeled (excuse my usage) here: goo.gl/m6X4FQ

    While the subject or subjects are particular to the given situation, this testimony provides a great example of staying on track without compromise or distraction–in any situation.

  10. 10
    Victor says:

    #4 Barton, I see via Google that you are a science fiction writer. Apparently, judging from your Wikipedia profile, you don’t have an advanced degree in anything, and there is no reference to a science degree. It says your first peer reviewed scientific paper was published in 2011, a long time to wait if you’re a trained scientist who graduated in 1983. I don’t have any degrees in science either, so I certainly won’t contest your right to be posting here or anywhere else. But I find it difficult to imagine that someone with your background could claim that you’ve refuted a paper by Justin Sheffield, a professor of Environmental Engineering at Princeton.

    Have you sent your paper to professor Sheffield, and has he conceded that he was wrong?

  11. 11
    patrick says:

    Ken Lassman @ 6, great questions. This may help if you work it:

    Climate Scoreboard widget with updating ticker showing nations’ pledges: “Increase in Global Temperature by 2100: Where will proposals from the climate negotiations lead?”:

    https://www.climateinteractive.org/tools/scoreboard/

    “The Climate Scoreboard shows the progress that national contributions (INDCs) to the UN climate negotiations will make assuming no further action after the end of the country’s pledge period (2025 or 2030). Our analysis shows that the national contributions to date, with no further progress post-pledge period, result in expected warming in 2100 of 3.5°C (with a range of uncertainty of 2.1 – 4.6°C).

    “The Climate Scoreboard uses the C-ROADS climate policy simulation model to analyze the impact of the “Intended Nationally-Determined Contributions (INDCs)—pledges to limit greenhouse gas emissions—to the UN climate negotiations. The Scoreboard analysis above shows the expected impact of the pledges nations have made to date, assuming (1) the pledges are fully implemented, and (2) assuming no further reductions beyond those that have been formally pledged, specifically, actions after the end of the country’s pledge period (2025 or 2030).”
    Plus preliminary analysis beyond 2030. If you read to the end of the “For example: …” you get an optimistic example step-wise scenario to 2 degrees C. Next webinar, Oct 6:

    https://attendee.gotowebinar.com/rt/2467644211219127298

    Follow this on Climate Interactive: https://twitter.com/climateinteract

    https://www.climateinteractive.org/tools/c-roads/

    Video: https://www.youtube.com/watch?t=146&v=DqEsDT86Fls

    I lament the soundtrack. Gavin retweeted:

    https://twitter.com/ddimick/status/648447596554530817

    Dennis Dimick and Justin Gillis, thanks a bunch.

  12. 12

    What can science contribute to the Paris process?

    I’d say, “Straight but sober talk, reinforcing the urgency of our situation. And lots of it.” As Killian says, we already know more than enough to determine what the rational macro-policy would be: step on the ‘brakes’, hard, wrt carbon emissions.

    Of course, it’s not just up to the climate science community how that message gets promulgated to policy makers and the public–as we’ve seen, often dismayingly, over the past decade and more.

  13. 13
    Peter Wright says:

    Would anyone like to estimate how much co2 is effectively displaced by a perfectly reflecting large roof with a slight incline to the south. My location is southern England. I ask as I have recently constructed such a roof (very white but obviously not 100% reflective) and am curious to know if its reflection of solar radiation is in anyway significant from the individual’s emissions point of view.
    Thanks

  14. 14
    Mike S says:

    The issues at COP21 are not about climate science, the consensus, crazy denier blogs or even snowball throwing senators. The main issue is who pays for what. For example, India says it has only contributed 3% to the global CO2 increase. But, many inventions made in the developed world benefit everyone. India would not even be talking about developing a modern, CO2 emitting, economy if the West had not led the way. But, how can this be quantified in a way that is fair, economically feasible, and politically acceptable? Mathematicians and social scientists have studied such things. What practical ideas can they bring to the table?

  15. 15
    Edward Greisch says:

    According to the World Health Organization

    “Climatic changes already are estimated to cause over 150,000 deaths annually.”

    http://www.who.int/heli/risks/climate/climatechange/en/

    What do you think? Is WHO reliable enough?

  16. 16
    James McDonald says:

    A reasonable contribution by scientists would be to present some major and easily understood consequences that would follow from various levels of action.

    For example, if you do X, we lose Miami and New Orleans. If you only do Y, we also lose Washington, DC. If you only do Z, we lose Boston as well.

    Make it very simple to see major consequences, and keep the effects close to home.

  17. 17
    Edward Greisch says:

    8 Bob Johnson: I recently “discovered” that it is necessary to get down to the itty bitty nitty gritty even though I am talking to non-physicists. Take your junior undergrad atomic physics book with you and talk about how CO2 molecules vibrate and scatter photons. Show spectra. Etcetera.

    As for some character on the web, it is free speech, so anybody can say anything. There is no knowing who or what the source is.

  18. 18
    Mal Adapted says:

    Tom Dayton:

    David Evans’s prominently, frequently self-proclaimed, and fervently defended “rocket scientist” labeling reeks of desperation for validation. He reminds me of that wack job who was promoting himself as an expert on delaying aging, whose main qualification in his public bio was his Graduate Record Exam score that is one of the test scores that grad schools use to screen applicants. (He never even went to grad school.)

    Hey, I resemble that remark 8^}! It was my score on the Advanced Biology part of the GRE that got me into a highly-regarded PhD program. It wasn’t enough to get me the PhD, though. After spending two years trying to screw in that light bulb, I discovered I really didn’t want to work that hard for validation, and found an easier way to make a living. It turns out that being paid to chop wood and carry water is sufficiently validating.

    Happiness lies in adjusting your ambitions to fit your abilities.

  19. 19
    Hank Roberts says:

    for James McDonald:

    Not “if” — “when” — we lose coastline.

    The AIP History pretty much covers all this stuff, if you can get people to read it: https://www.aip.org/history/climate/floods.htm

    Some 400,000 years ago the temperature had been only a few degrees higher than at present, but the sea level had been more than six meters higher. An ingenious study of sediments found that southern Greenland had been largely ice-free at that time, and thus the island had been a main contributor to the sea-level rise. By the end of the century, if emissions of greenhouse gases continued, our civilization might well have locked in a grand change of the ice sheet and therefore of sea level.Footnote 30a

    Footnote:

    30a. Greenland ice stream acceleration: e.g., Rignot and Kanagaratnam (2006), also, small earthquakes in Greenland, caused by sliding glaciers, had become twice as frequent: Ekström et al. (2006). Slowdown: Howat et al. (2007). Mass loss: e.g., Chen et al. (2006); Luthcke et al. (2006); Zwally et al. (2005); another satellite: Pritchard (2009). Accelerating: Rignot et al. (2008); Velicogna (2009). Long-range study: van de Wal et al. (2008). A more recent study showing substantial mass loss: Csatho et al. (2014). Greenland 400,000 years ago: Reyes et al. (2014).

  20. 20
    Anonymous Coward says:

    Digby Scorgie (#2),
    It’s not that simple.
    You say “no more than two degrees of warming with a probability of 50%” but you don’t specify the baseline period or the timeframe in which you want to avoid a larger warming. For instance, going by AR5, it looks like RCP4.5 emissions would yield >50% probability of less than 2C over present temperatures in 100 years. But if you look 200 years out instead or alternatively choose to compare with late-20th century temperatures, the probability drops under 50%.
    I think you ought to look at RCP4.5 even though the emissions cuts aren’t as aggressive as what you’d want because there’s a wealth of information available as to the projected outcomes of RCP4.5 and if nothing else it’d help you determine how to better specify the simple statement you’d like to see (what’s the most relevant time horizon, whether it might be advisable to rule out a higher level of warming with a >95% probability instead and so forth).
    RCP4.5 is also interesting in that although I think it’s already been overshot, it’s a lot more realistic than what you proposed as an example. In particular, in the immediate future it only requires global emissions growth to slow rather than actually go negative (they’d have to go negative within 30 years or so, see table 2.1a in AR5 WG1, Annex II for instance).
    Finally, RCP 4.5 answers one of the questions implicit in your post in that its fossil fuel emissions do not drop to zero after the period of cuts but remain comfortably large. Yet the outcome is not to far off from what the goal you seem to have in mind.

  21. 21
    Tony Weddle says:

    I’d like to see some consensus from scientists on what global reductions are necessary to have a good chance (80%-90%) of limiting warming to 2C above pre-industrial. Kevin Anderson has given it a go and thinks 10% per year from about now, is needed to just have a 66% chance. So what is the consensus on this?

    I’d also like a scientific examination of what would be dangerous warming. Are we already there (currently, I believe it is over 1C above preindustrial) or have we still got wiggle room? What would an earth warmer than 1.99C above preindustrial look like? And what is the likely end point for future generations, for various budgets (i.e. not stopping at 2100, but what is in store for future generations and how quickly).

    Lastly, emphasize that uncertainties can cut both ways. Curry likes to harp on about the uncertainties but comes across as certain that they will all result in a much lower ECS (and note that we’re already above +1C). That is crazy; if there are uncertainties, things could be worse than the models project.

  22. 22
    sidd says:

    Re:”how much co2 is effectively displaced by a perfectly reflecting large roof with a slight incline to the south. My location is southern England.”

    from

    http://www.realclimate.org/index.php/archives/2015/10/unforced-variations-oct-2015/comment-page-1/#comment-636315

    I like white roofs in urban areas. But need more data. Area of roof, angle and orientation insolation charts, HVAC loads, gas/electric/wood/coal supply, and such. But a good number to begin with is that CO2 forcing is somewhere around 0.5 to 1 W/sq. m. currently. I think Prof. Chu had some data on white roofs for the USA.

    Re: “The main issue is who pays for what. For example, India says it has only contributed 3% to the global CO2 increase. But, many inventions made in the developed world benefit everyone. India would not even be talking about developing a modern, CO2 emitting, economy if the West had not led the way.”

    from

    http://www.realclimate.org/index.php/archives/2015/10/unforced-variations-oct-2015/comment-page-1/#comment-636315

    So if a large wall surrounding India were to repel Vasco da Gama and other contact with the “West,” and India had remained, say, in Mughal imperial grip, the 3% burden would disappear and the “West” ought to pay for the putative 3% of CO2 load today due to India ? Further, I question the 3% figure in the light of Ruddiman’s work. Fossil fuel emissions are merely the latest burdens humans have laden upon the rest of nature.

    Re:”if you do X, we lose Miami and New Orleans. If you only do Y, we also lose Washington, DC. If you only do Z, we lose Boston as well.”

    from

    http://www.realclimate.org/index.php/archives/2015/10/unforced-variations-oct-2015/comment-page-1/#comment-636315

    I suggest different phrasing, since now we are just talking about times and prices.

    “By when would you like to lose Miami ? New Orleans ? Washington ? How much would you care to pay per extra year prior to full abandonment ?”

    Isn’t that what the economists swear by, expressed preference, in terms of cash on the barrelhead ?

    The cynic in me imagines that arguments of this sort will probably skip Bangladesh, where imperiled population dwarfs those of the cities mentioned, are too poor to count, being in Chris Hedges’ epigram : the sacrifice zones.

    sidd

  23. 23
    Russsell says:

    15. asks :

    “What do you think? Is WHO reliable enough?”

    Certainly not, and even more self-serving and less representative.

  24. 24
    MA Rodger says:

    Peter Wright @13.
    I’ve done this calculation before and concluded that painting a large UK house roof white would mitigate roughly 9 months-worth of the occupants carbon emissions.
    Repeating the exercise now, I calculate 19 months. I think the house is perhaps a little more generously proportioned this time (200 sq m). The result is thus reasonably robust.
    I would therefore suggest that delaying AGW by ten months or so is not going to persuade many folk that painting their roofs, their car, their lawn, their cat white is a must-do duty.

  25. 25

    V: #4 Barton, I see via Google that you are a science fiction writer . . . you don’t have an advanced degree in anything, and there is no reference to a science degree.

    BPL: B.S. in Natural Sciences, dual physics and computer programming major, University of Pittsburgh 1983.

    V: It says your first peer reviewed scientific paper was published in 2011, a long time to wait if you’re a trained scientist who graduated in 1983.

    BPL: And my second was in 2015. And I wasn’t working as a physicist, I was working as a computer programmer.

    V: I don’t have any degrees in science either

    BPL: Believe me, that’s evident from your every post.

    V: Have you sent your paper to professor Sheffield, and has he conceded that he was wrong?

    BPL: I sent him an earlier version, and no, he did not. On the other hand, he insisted the NOAA version of the Dai et al. dataset used the Thornthwaite equation for evapotranspiration, when it fact it explicitly used the Penman-Monteith equation. So he’s not perfectly reliable, is he?

  26. 26
    concerned european says:

    I am not a mathematician, but the easiest way to account for the share of states would be based on the total area of states. Discounting Antarctica and Greenland (the last is debatable), the area share of India is about 2,4%. So if India has already contributed 3% of the global CO2 increase, then it is already above average. Cumulative accounting would be more fair, but reaching such an agreement would be more difficult. Thus, the simple way in my opinion should be to set the annual emission goals for, say, the year 2050 based on the share of state area and then set the constant annual decrease rates for individual states. Longer-term goals become more complex again because of rising sea levels and shrinking state areas. I would strongly prefer a share based on the area, not on the population census, because the latter might give incentives for mass migrations. Responsibility can be backed by very-long-term biotope cohabitation, mass migrations would hamper responsible behavior.

  27. 27
    Hank Roberts says:

    for Peter Wright:

    Reflectance is one factor; emissivity is another, more important to consider. Look up both for the material you’re considering, they’re different, not intuitively obvious.

    Also ‘oogle for discussion of condensation under cool roofs, as a surface that’s very efficient at losing heat to the sky (emissivity) will consistently be cooler than the surrounding air and (like car windshields and roofs) will condense water from the air.

    That condensation will happen on both top and bottom to the extent air circulates through the attic, unless you’ve put airtightinsulation on the underside of the roof.

    You can end up with a white, high emissivity roof that rots your attic. Adding ventilation brings in more moist air that leaves more water there.

    Shorter: no simple answer to your question, and nobody understood this problem even a few years ago when they started promoting the approach.

  28. 28
    Jim Baird says:


    The Copenhagen Accord
    commits 115 nations to “limiting the maximum global average temperature increase to no more than 2 degrees Celsius above pre-industrial levels, subject to a review in 2015.”

    It also includes a reference to consider limiting the temperature increase to below 1.5 degrees – a demand made by vulnerable developing countries.

    The 1998–2012 hiatus shows a decadal average temperature rise of 0.05C compared to the 0.12C increase per decade rise over the period of 1951-2012.

    The main reason for the slowdown is assumed to be a greater uptake of heat in deep ocean waters.

    By the end of this year it is likely the global average temperature increase will have reached 1 degree Celsius above pre-industrial levels.

    IMHO, the path to a 1.5 degree future or less, is pretty clear.

    Most climate scientists call for eliminating carbon emissions but there is little evidence we can get an equivalent amount of energy to what the world is currently consuming from any other energy source than by moving surface ocean heat to the deep through a heat engine soon enough to keep the world to 2C let alone 1.5C.

  29. 29
    mike says:

    Role? Speak up loudly at every opportunity in a public manner to help the public understand the impact of global warming on our lives. Case in point: http://www.theguardian.com/us-news/2015/oct/04/south-carolina-flood-governor-nikki-haley-deaths-thousand-year?CMP=ema_565a

    “once-in-a-millenium” flooding in South Carolina and coverage does not mention global warming one time. Connect the dots folks. The public can’t figure this out without consistent orientation between extreme weather events and the burning of fossil fuels. Stop playing the “we can’t say for sure that this event is caused by global warming” confusion game and speak loudly about what you can say: “This event is definitely influenced by the heat being absorbed by the oceans. More extreme events like this one will be more and more common as the oceans warm, large ocean currents are disrupted and our ocean-driven weather patterns change.” Call out Gov Nikki Haley if she talks about the SC flooding and does not acknowledge that global warming is changing weather patterns and torrential rains is one of the changes happening. She needs to answer to the citizens of her state for her position on global warming.

  30. 30
    mike says:

    Quote in the NYT coverage of the SC flooding:

    “I’ll put it this way: For us, this is a biblical event,” said Mr. Hinton, 32, a big man in an orange wet suit. “This is a historical-type deal.”

    Nothing about rising sea levels, global warming, etc. Flooding and hurricanes seem more like weather and climate events though I understand that flooding has biblical context as well, but when the news coverage chooses to carry biblical quotes and zero on global warming, I have to comment on the political agenda that is driving the coverage.

    So what role should climate science play in the upcoming COP21? I don’t know. How about comic relief? Can climate science do some funny graphics? As I have been told here, the scientific community does not have a mouth, so I am not sure why we would wonder about a role for climate science at COP21. Who is going to dress up and function in a climate science role at COP21?

  31. 31
    mike says:

    I will note that a comment I left last month that quoted Michael Mann for underestimating some aspects of global warming predictions never cleared the filters here. In the comment, I was referenced quotes from Dr. Mann regarding his failure to get the prediction right, so this is not me saying Mann got it wrong, Dr. Mann said he got it wrong.

    If climate science wants a role at COP21, how about estimating the consequences on the high side, present the consequences in a cost benefit analysis that spells out how the costs increase exponentially as inaction continues? I like the suggestion

    Sacred cows, anyone?

    Killian at #7 has it right. Stop talking in hypotheticals about things we know, like Miami and NO will be underwater, nothing we can do but move those communities. And that is just two communities in one nation.

  32. 32
    Dan H. says:

    James,
    You may want to add a time table to your consequences. For example, we lose Miami in 2100, New Orleans in 2300, etc.
    The problem with previous assertions of coastal flooding was that the general public was under the impression that they would occur within their lifetime.

  33. 33
    Anonymous Coward says:

    Tony Weddle (#21),
    Taking AR5 as an approximation of the consensus (I guess some might object), it looks like RCP2.6 yields probabilities close enough to what you’re asking (see tables 12.3 and 12.2, WG1). Though you might have a different way to come with probabilities in mind.
    RCP2.6’s emission cuts while unrealistic aren’t anywhere as fast as 10% per year (when considering the initial decades that is, percentage-wise the year-on-year cuts become very steep as the emissions approach zero).

    In addition to the tables mentionned above, chapter 12 of AR5 WG1 has the post-2100 modelling you are interested in.

  34. 34

    Perhaps a useful contribution by scientists at CoP21 would be to have prepared an answer to the question of just why the 8 major interactive positive feedbacks now reported to be accelerating are going to stop interacting and amplifying the warming simply because of a gradual constraint of anthro-GHG outputs that raises global temperature >2.0C above what is natural for this century’s insolation levels.

    With major Parties already de-facto committed under “net-zero” goals to some form of the Carbon Recovery mode of Geo-E
    -(usually referred to as ‘forestry’ or so-called ‘BECCs’ but without any account of the reduced viability of forestry under dangerous levels of AGW)-
    the answer to the question of why the feedbacks would halt is essential if the Parties are to forgo an unspoken reliance on the future use of the Albedo Restoration mode of Geo-E.

    OTOH, scientists could acknowledge that there is no sound confidence of the feedbacks halting under more than 2.0C of AGW, as by that point they may well be fully self-reinforcing, with their CO2_e output exceeding that saved by the UNFCCC’s constraints to anthro-GHGs.

    If this was acknowledged, the logical call at CoP21 would be for for the establishment of a UN scientific agency for the accreditation and supervision of global research of both modes of Geo-E, with any unsupervised trials, or any deployments not authorized by the UNGA, being outlawed and heavily penalized.

    So what are the arguments that the feedbacks would be halted by limiting anthro-GHGs to say a 3.0C equivalence ?

    Regards,
    Lewis

  35. 35

    “I would strongly prefer a share based on the area, not on the population census, because the latter might give incentives for mass migrations.”

    Every denialist in Canada is strongly preferring the same, as it minimizes her responsibility to mitigate. Not fair, given that Canada is a top ten emitter in absolute terms, and pretty darn high on the list in per capita terms–of OECD nations, just a tick below the US and Australia, if memory serves.

    And speaking of Australia, her denialists should be pretty pleased, too; the same dynamic would apply there.

  36. 36
    Dan Smith says:

    Greetings all who know much more than I on the climate front. I follow climate science incessantly (because without a viable ecosystem, everything else seems moot), and I admit that much of the detailed analysis you do on this site is over my head. I’ll jump on to Nature Bats Last and then flow into Skeptical Science for updates and hit up some Climate Crocks for good measure, but I’m by no means at your level on the understanding of this science. And am by no means completely bought into any particular perspective

    My question: At what point do we get a bit panicky? 2014 was the hottest on record, 2015 is looking to be the next hottest year on record… and with self reinforcing feedback loops, do you personally feel like we can back this train up? Perhaps I’ve been listening/reading to too much “Doomer” news, but based on the infinite growth paradigm we exist in, do you REALLY believe that we can solve this in time? Any input is appreciated.

  37. 37
    Tony Weddle says:

    Dan, what does Hansen’s latest paper have to say about the timeline? I haven’t found time to read it, yet but I suspect it suggests that the timelines could be much shorter than you state. Don’t know, though.

  38. 38
    patrick says:

    Re: my comment @6, this link works. Or use Hank’s @243 last month. It’s Andrew Dessler.

    Although the situation is different from Cop21, this testimony is a fine example of staying on track without compromise or distraction, I thought.

    https://www.edockets.state.mn.us/EFiling/edockets/searchDocuments.do?method=showPoup&documentId={78E47E70-A374-4720-8BF8-8B4CB42D38A0}&documentTitle=20159-113910-04

  39. 39
    Hank Roberts says:

    For Tony Weddle, here’s what Hansen’s latest paper has to say about the timeline: http://phys.org/news/2015-09-eyes-oceansjames-hansen-sea.html

    Compare descriptions you get from different sources to detect spin.

  40. 40
    Richard Caldwell says:

    Hank Roberts: Not “if” — “when” — we lose coastline.

    RC: The most valuable land on the planet is coastline. It’s hard for me to imagine us giving up coastline without a fight. Thus, we’ll geoengineer. Thus, we probably won’t lose significant coastline. How much is Miami alone worth? Do you really think we’ll just toss all that cash in the ocean when there’s a cheap and guaranteed way to prevent it? We’re playing with weather patterns anyways. Doing it in a way that probably lessens weather distortions as compared to our current path doesn’t sound irrational. Pretending we haven’t been actively geoengineering the planet for over 100 years does sound irrational. Hank, do you personally think we’ll willingly sacrifice Miami instead of trying solar radiation management? That’s a yes/no/won’t-come-to-that with explanation, please.

    concerned european: I would strongly prefer a share based on the area, not on the population census, because the latter might give incentives for mass migrations.

    RC: Sounds backwards to me. If Russia and Canada strike it rich in “allowed emissions”, then wouldn’t there be even more of a mass migration there than we’ll likely see under per capita emissions? You’re also saying that tiny states like Vatican City and the Gaza Strip get squeezed out while big countries like the USA benefit greatly. Again, sounds backwards. Big countries have more room for renewables.

    concerned european: Responsibility can be backed by very-long-term biotope cohabitation, mass migrations would hamper responsible behavior.

    RC: By “very-long-term biotope cohabitation” do you mean “folks get used to their local weather, plants, and animals”? Since few if any areas on the planet will retain their traditional biotope, a lack of migration won’t increase biotope continuity. Besides, biotope continuity is only important within each generation. Subsequent generations don’t care. For example, people don’t even know of the huge loss of bird life in the USA over the last 200 years. Passenger pigeons used to block out the sky. I also don’t understand how mass migrations hamper responsible behavior. Please explain.

    Dan Smith: with self reinforcing feedback loops, do you personally feel like we can back this train up? Perhaps I’ve been listening/reading to too much “Doomer” news, but based on the infinite growth paradigm we exist in, do you REALLY believe that we can solve this in time?

    RC: The ocean will continue to suck up CO2, so in theory we could drop CO2 levels back to perhaps 350ppm (not a rigorous estimate) without anything esoteric such as artificial trees. And, there’s always solar radiation management. It wouldn’t do anything about ocean acidification, but it would cool the planet, giving us a bit more time to switch to zero carbon energy sources. So, yes, I think we can solve this in time, but we’ll do it sloppily enough that many people, species, and ecosystems will perish.

  41. 41

    “When do we lose Miami?”

    Good question, and not easy to answer; we don’t know what policy choices may emerge from COP 21, nor from the political processes around the world which have been leading to a global-scale multiplication of mitigation policies for some time. And we also don’t know exactly how the trajectories of warming and SLR will play out over time; denialati like to presume that the latter will be exactly linear, but that does not, from physical considerations, seem like a very good bet. And the one takeaway that’s pretty solid from the ‘faux hiatus’ is that natural variability remains very significant.

    But one thing we can approximate a bit better is, how much SLR would be problematic for Miami? Consider the linked visualizer tool:

    http://coast.noaa.gov/slr/

    You can select Florida from a drop-down menu, then double-click to zoom in to a level that lets you look at the Miami metro area. You can then use a slider to select from 1-6 feet of SLR, in one-foot increments.

    When I play with that a bit, what I get from it is this:

    1-2 feet look pretty innocuous on the map, but, considering the flooding areas get now, I’d guess that those kinds of additional flooding would cost as much as hundreds of millions.

    At 4, the geographical continuity of the area is severely compromised.

    At 6, so much of the area is inundated that it’s fair to say that Miami would be ‘lost.’

    So–just to benchmark a bit–if the conservative ‘worst case’ 3-foot GMSL projection from AR5 is realized, then Miami will be suffering severe economic harm by the end of the century–perhaps severe enough, just from SLR, that it will be in a position then somewhat similar to Detroit’s today (though with the important exception that further deterioration would be guaranteed in the Miami case.) In other words, catastrophic population and economic losses.

    If Hansen’s more aggressive scenarios pan out–10 feet in 50 years–then Miami is toast sometime before 2065. A linear rise at that rate would imply ‘toast’ (soggy toast, presumably) around 2045, but linear would likely be biassed on the early side. So we can guess that Miami can almost certainly enjoy another generation’s worth of life at the present location (ignoring all perils except SLR), albeit under increasing economic pressure.

    https://www.ipcc.ch/pdf/unfccc/cop19/3_gregory13sbsta.pdf
    http://ecowatch.com/2015/07/21/james-hansen-climate-report/

    Another question worth asking, though, is “When is Miami committed to inundation?” According to a Benjamin Strauss commentary in “Nature” a couple of years ago, the answer is “probably between 2020 and 2025.” And that’s not very sensitive to the emissions scenario, so Miami may, as a practical matter, not be savable now: if we can’t do as well as RCP2.6, which many would argue to be the case, then commitment of Miami to inundation is purely a matter of time.

    http://assets.climatecentral.org/pdfs/Strauss-PNAS-2013.pdf

  42. 42
    turboblocke says:

    IMO the two main beneficiaries of geo-engineering will be the lawyers and the arms industries.

  43. 43
  44. 44
    alan says:

    Sorry pretty much not about COP21 but its question I wanted a good answer to: El nino is a phenomena, .. blah blah. Some indices measure pressure differential (SOI), and I see that as a measure is intrinsically robust against climate change. TBMK, some of the others measure SST in a region versus a baseline over time (ENSO3.4,+…) however as oceans heat up that index will wind up permanently positive, but again TBMK it is the difference in SST between east and west pacific that actually controls whether or not we are in an El nino (which way the wind blows). Is that how it is or have I missed something? I guess it is related to understanding just how bad Climate change is economically, does it create a permanent El Nino(warm SST), or is it actually SST differences that effect El Nino.

  45. 45
    Digby Scorgie says:

    A Coward (#20)

    The topic is the role of climate science at the Paris conference. I’m trying to envisage a simple statement (or set of statements) that gets across to policy-makers the stark reality confronting us. Everyone is just wittering on about emissions, emission profiles, emission-reduction pledges, and so on ad nauseam. There is no talk of how these reductions are to be achieved. Instead of being fixated on the fetid carbon-laden breath of the beast, why not simply walk around behind it and kick its arse?

    But you have done me a service, AC. I now see that I was stupid to include too many numbers in my example, numbers that are merely a distraction. So I’ll try again. I suggest that climate scientists should provide policy-makers with information on the recommended rate for cutting fossil-fuel production so as to avoid catastrophe (or a set of increasingly unpleasant future climates, described in purely qualitative terms — for example (1) difficult (2) dangerous (3) disastrous (4) utterly catastrophic). Here is my example again, thus rephrased:

    “To avoid dangerous climate change, the production of fossil fuel must be cut every year by an amount equal to 4% of 2015 production, beginning in 2016 and continuing for the next 24 years.”

    The figures of 4% and 24 years (allowing for a small “floor”) are just wild guesses on my part. I do not have the expertise to supply authoritative numbers. I note, for example, that cuts of 10% per year are being bandied about a lot, and there is no consensus on the period for decarbonizing. I only get bogged down and confused when I try to deduce such things from the AR5 SPM. It’s for climate scientists to provide the proper numbers, but nevertheless the above is the nature of the information I’d like to see them impart.

    All right, AC, what do you say now?

  46. 46
    Anonymous Coward says:

    Dingy (#43),
    I suspect the reason you are having trouble with the SPM is that, by design, what you want isn’t in there. Some assembly is required because it’s not a prescriptive document. That would make it political.
    I agree your example of the kind of statement you’d like from scientists is now clearer… but it also makes it clearer that you don’t want a scientific statement. The numbers you conceive as an encumbrance are what ties such statements to science. Scientists may of course enlighten us with their political opinions but that’s not what they’re uniquely qualified to do.
    And so I think the main role of scientists is to provide numbers, a big steaming pile of them. Politicians and their staff are better qualified to craft qualitative statements appropriate to the political situation. If they are unwilling to do even that, scientists will not be able to solve the underlying political problems by trying to do the politicians’ job for them.

    For what that’s worth, from a political perspective, my opinion on the type statement you wish for is that you are 25 years late.
    Given the present circumstances I think your approach is lacking in realism not only as to what the political hurdles are and as to the costs of mitigation but also as to the extent of the damage that’s already been done.

  47. 47
    Dan Smith says:

    Hank Roberts

    Thanks for your reply, that does give me slightly more hope. But I do have to say the general “mood” of the scientific community on this site is less optimistic then then the popular media (but perhaps my perception is skewed).

    If my perception is not skewed, then is the reality because of

    A) The desires of the beneficiaries of business as usual (the media/companies that fund them)?

    B)The natural tendency of scientists to be conservative with their claims?

    C) Hopelessness is not actionable?

    Of course the weight of each one of these claims makes its way into reality, but is there one that is the most powerful?

    Just trying to understand, any thoughts are appreciated.

  48. 48
    Richard Caldwell says:

    Dan Smith: At what point do we get a bit panicky?

    RC: When companies start writing off fossil fuel reserves and/or when Arctic summer sea ice disappears. We’re almost there.

    turboblocke: IMO the two main beneficiaries of geo-engineering will be the lawyers and the arms industries.

    RC: I’m thinking that lawyers and arms industries would do even better without geoengineering. Four degrees C and a few meters of sea level rise would clear out all the coasts and much of northern and central Africa, southern Asia, Central America, and northern South America to boot. Where ya gonna put all those billions of people? Won’t all of them have a legal claim against the USA et al? Won’t many of them buy cheap AK47s and RPG7s? I really can’t see how you can logically get to the opposite conclusion…..unless you’re buying into Flowers and Love and Saudi Arabia and Russia et al will willingly not pump oil and gas any more as of next year. You, of course, will be expected to both send your automobile to a compactor and pay off the loan. Of course, your gas stove, hot water heater, and furnace will be ripped out and trashed. You willing? Can you name any time when any oil producer voluntarily produced less than 80% of their maximum possible production, or any time they couldn’t find a buyer at a profitable price? (I suppose Shell’s Arctic Oil fiasco might qualify) Producers will produce at whatever price the market fabricates, and somebody will buy the goods. You will not willingly trash your fossil fuel powered goods, nor will you willingly triple(?) your electrical rates so power companies can trash their coal-fired plants and build solar farms. Life will go on fossilly….

  49. 49
    Edward Greisch says:

    Climate scientists: You may as well not attend COP21 because you have already surrendered. 23 Russell: If nobody died, you don’t have a case. It is like the FAA: If nobody died in a plane crash, they don’t make a new rule. The Federal Aviation Administration is a tombstone agency. As 7 Killian said: “scientists can help with making the science visceral for policymakers and public by stepping just a little outside their reticence and traditional roles as scientists by speaking to risk in more secular, policy-based terms.” I think several people have hinted that you need a new attitude. No more milk-toast. No more droning on about General Circulation Models. If you must talk science, talk about atoms and molecules.

    Climate scientists need a personality change before going to COP21. To win, you need to come on like gang busters. Because you are gang busters. You have to take over the meeting from people who have always won every shoe banging session they have ever been in. That is what it comes down to: take off a shoe and use it as a gavel. Bang louder than anybody else. Put steel heels on your shoes. Bring in a coffin and write “Charles Koch” on it. Get really angry. Make them fear you. Make damn sure they fear Mother Nature’s wrath. That is how you win.

  50. 50