William (good name!) Nordhaus has a new study out. The purveyors of snake oil seek to convey to the impressionable youth that he has changed his mind. However, it is a touch unclear in what manner his mind has change. Let’s try reading the abstract:

Climate change remains one of the major international environmental challenges facing nations. Yet nations have to date taken minimal policies to slow climate change. Moreover, there has been no major improvement in emissions trends as of the latest data. The current study uses the updated DICE model to present new projections and the impacts of alternative climate policies. It also presents a new set of estimates of the uncertainties about future climate change and compares the results will those of other integrated assessment models. The study confirms past estimates of likely rapid climate change over the next century if there are not major climate-change policies. It suggests that it will be extremely difficult to achieve the 2°C target of international agreements even if ambitious policies are introduced in the near term. The required carbon price needed to achieve current targets has risen over time as policies have been delayed.

(my bold). The highlighted phrase doesn’t suggest change; but it is a new paper so there must be something new in it. We can also read the breathless write-up although that may not be good for us:

Nordhaus has mostly argued for a small carbon tax, aimed at achieving a modest reduction in emissions, followed by sharper reductions in the medium and long term. Too much mitigation now, he has suggested, would damage economic growth, making us less capable of doing more in the future. This view has helped fossil fuel companies and climate change skeptics oppose any serious policy response.

In his latest analysis, though, Nordhaus comes to a very different conclusion. Using a more accurate treatment of how carbon dioxide may affect temperatures, and how remaining uncertainties affect the likely economic outcomes, he finds that our current response to global warming is probably inadequate to prevent temperatures from rising more than 2 degrees Celsius above their pre-industrial levels, a stated goal of the Paris accords.

I find that baffling. The sentence …comes to a very different conclusion is then followed by nothing different from what went before. That our current response is inadequate is nothing new; we don’t (globally) have even a modest carbon tax. That you have to ramp up the response in the future if you do nothing now is also not new. Since N has been saying this for decades, we’re now in the medium term.

Enough, what of the actual study?

OK OK. Let’s start with the revised DICE model shows more rapid growth of output and a higher temperature trajectory in the baseline path compared to earlier DICE versions and most other models. This is also reflected in a major upward revision in the social cost of carbon (SCC) and the optimal carbon tax in the current period because that sounds interesting.

Before that, a brief diversion into uncertainty:

the social cost of carbon (SCC) is higher (by about 15%) under uncertainty than in the certainty-equivalent case because of asymmetry in the impacts of uncertainty on the damages from climate change.

This will be music to mt’s ears, although he may be “disappointed” by the mere 15% weighting on uncertainty. Since I can immeadiately understand roughly where they’re getting this kind of number from, I didn’t bother actually read that bit. Oh, and there’s also the rather-nice-to-see-explicitly-written:

relative uncertainty is much higher for economic variables than for geophysical variables… primarily because of the large uncertainty about economic growth.

Back to the main strand. We come to Damage function: core estimates which is also interesting. In fact, lots of this paper is interesting; why am I reading it for you? You should read it for yourself. We find:

The damage function was revised in the 2016 DICE version to reflect new findings. The 2013 version relied on estimates of monetized damages from the Tol (2009) survey. It turns out that that survey contained several numerical errors (see the Editorial Note 2015). The current version continues to rely on existing damage studies, but these were collected by Andrew Moffat and the author and independently verified. We examined different damage estimates and used these as underlying data points and then fitted a regression to the data points. We also added an adjustment of 25 percent of the damage estimate for omitted sectors and non-market and catastrophic damages, as explained inNordhaus and Sztorc (2014). Including all factors, the final estimate is that the damages are 2.1% of global income at 3 °C warming and 8.5% of income at 6 °C warming1.

(my bold). His “optimum” (in the cost-benefit economic sense) trajectory comes in at about 3.5 oC by 2100, for a point of reference. We also see A major surprise and difference from earlier versions of the DICE model is that the “optimal” trajectory is now closer to the “base” that to the ambitious scenarios. This is due to a combination of factors such as climate-system inertia and high costs of the limiting scenarios. What I take that to mean is that the economically-optimal trajectory is now further from ambitious than before (which was not the point the snake-oil salesmen wished us to receive), because they’re too expensive.

Having now fought my way to the SCC part, I’m having a hard time understanding his major upward revision in the social cost of carbon. Because there are so many numbers to read. His preferred number, $37, seems to have increased to around about the currently-preferred for US regulatory purposes” value of $45.

So, there you go. the paper is worth reading, or at least skimming, but hardly amounts to a revolution. Quite the reverse: just an incremental tweaking of the model and a write-up of the same.

Head to head, leg 2. We’re only at about 32 I’m afraid.

Notes

1. I won’t harp on about this, but you see immeadiately from this that, for example, reducing GHG’s in such a way as to halve economic growth from now to then would not be economically efficient, if it merely saves us 2.1% damage.

Refs

* Two Parts Of Dodd Frank That Trump’s Executive Orders Really Should Repeal
* Assam’s Missing Subsidised Rice – The Importance Of Aadhaar And Direct Benefit Transfer – Timmy; I include it just for the immortal That India is going to have a welfare system of some sort is obvious – everywhere else does and the Randian fantasies of no government redistribution ever are simply not going to happen to wind up the usual wackos.
* Elon Musk: At my request, the agenda for yesterday’s White House meeting went from not mentioning the travel ban to having it be first and foremostIn addition, I again raised climate. I believe this is doing good, so will remain on council & keep at it. Doing otherwise would be wrong.

Comments

  1. #1 Andrew Dodds
    United Kingdom
    2017/02/04

    6 degrees of warming costing 8.5% of income seems a tad optimistic, given that it puts almost every coastal city underwater and renders significant areas unfit for habitation due to wet bulb temperature limits..

    [Maybe. How much SLR are you guessing from +6 oC to make your judgement? IPCC AR5 says For the period 2081–2100, compared to 1986–2005, global mean sea level rise is likely (medium confidence) to be in the 5 to 95% range of projections from process based models, which give 0.26 to 0.55 m for RCP2.6, 0.32 to 0.63 m for RCP4.5, 0.33 to 0.63 m for RCP6.0, and 0.45 to 0.82 m for RCP8.5. For RCP8.5, the rise by 2100 is 0.52 to 0.98 m with a rate during 2081–2100 of 8 to 16 mm yr–1 -W]

  2. #2 Hank Roberts
    2017/02/04

    “… Including all factors, the final estimate is ….”
    I suspect the presumption there is wrong.

    http://www.smithsonianmag.com/smart-news/how-will-climate-change-impact-plankton-180955387/

  3. #3 Kevin O'Neill
    United States
    2017/02/04

    Isn’t the most fun part:

    The damage function was revised in the 2016 DICE version to reflect new findings. The 2013 version relied on estimates of monetized damages from the Tol (2009) survey. It turns out that that survey contained several numerical errors (see the Editorial Note 2015). The current version continues to rely on existing damage studies, but these were collected by Andrew Moffat and the author and independently verified.”

    He’s thrown Tol under the bus. I mean, he didn’t have to mention Tol’s errors – he could have just baldly stated the damage function was revised and who collected the data; leaving it to the informed reader to read between the lines. But he put it right out there where no one could mistake (sic) the reason why :)

  4. #4 Andrew Dodds
    United Kingdom
    2017/02/04

    To be honest, 6 degrees of warming is ‘here be dragons’ territory. The equilibrium response from paleo gives us the complete loss of the GIS and WAIS plus most of the EAIS, so 30m minimum sea level rise. How fast is speculative; we have never seen the system so far from equilibrium.(than +6 degrees in a century)

    [I don’t think you’re allowed to invoke equilibrium response from palaeo by 2100. 30 m SLR by 2100 would obviously be a disaster -W]

    Add in the climate zone shifts, and related population shifts, and inevitable wars.. we would count ourselves fortunate to still be measuring GDP, never mind being a few percent down. The extrapolation in the paper seems divorced from the physical reality.

  5. #5 Phil Hays
    Americanistan
    2017/02/04

    IPCC AR5 “does not include the potentially large increases in outflow that may be associated with the MISI discussed below.”

    While we might get lucky, we might not.

  6. #6 MMM
    2017/02/05

    Regarding the response to comment 1: I’m no Jim Hansen with ridiculous estimates of plausible sea level rise by 2050, but I think the community generally regards the IPCC SLR estimates to be rather conservative, especially at the high end – e.g., see the recent US National Academies and USGCRP assessments. Mainly due to increasing potential upper bound uncertainty from ice sheet melt. And 6 degrees C warming is well on the upper bound of RCP8.5 possibilities, so really I’d think that well over a meter would be likely at that kind of temperature.

    Still, 8.5% of income could cover a lot of coastal damage and uninhabitable tropical zones…

  7. #7 Hank Roberts
    at the reference desk again
    2017/02/05
  8. #8 David B. Benson
    United States
    2017/02/05

    The current concentration of carbon dioxide is now 400 ppm. The previous time that it was so high was the mid-Pliocene with global temperatures over 2 °C higher than now and sea levels about 25 meters higher than now. So if carbon dioxide levels remain that high the same conditions will obtain at equilibrium. I suspect that will take a millennium or more.

    Such high sea stands are likely to be seriously damaging to the global economy.

    Reference:
    https://en.m.wikipedia.org/wiki/Pliocene_climate

    [It does seem rather likely that temperatures that high will, over the long term, lead to SLR in the tens of meters. However, that’s a commonplace. The question is how long is the long term, and how much should we care about the long term? I’m reluctant – as I’ve said before – to care about more than 100 years ahead. Because we can’t plan that far. Would it be useful to care about 1000 years in the future? Would we have thanked folks 1000 years ago had they attempted to care about us? -W]

  9. #9 Fergus Brown
    http://whogoeswithfergus.blogspot.co.uk
    2017/02/05

    Sea level rise: my blog post of 30th January features Brunnabend et. al., which addresses this: I found it an interesting read.
    You are right to point that that there is a pay-off between present costs and future benefits, but the ‘real cost’ is an open argument right now, and reducing the growth of GHG’s (rather than geoengineering the existing atmosphere) has a lower net cost, and a higher net benefit, taking environmental and social impacts into account, than is often used in economic analysis (because its hard to measure and so often left out).

    [You’re allowed to link to your stuff :-). I’ll do it: http://whogoeswithfergus.blogspot.co.uk/2017/01/when-will-gulf-stream-shut-down-and-how.html. I only skimmed it I’m afraid: I already know what I think about the GS. I agree that reducing GHG is better than geoeng. I also agree that the env+soc impacts are hard to gauge. But, they will be -W]

  10. #10 Arthur Smith
    2017/02/05

    So the uncertainty calculation seems new and interesting. Are there 2-sigma uncertainty bars given for that $45 number?

    I am surprised they are still limiting calculation of effects to 2100. There are plenty of children around today who will still be alive then. We’ve been worrying about this for around 40 years now, we should be looking at damages at least to 2150 or preferably properly weighted to much further out.

    [Well, see my comments above about timescales. I’m not sure what a reasonable cut-off ot trail-off point might be. Maybe 2150 -W]

  11. #11 Tim Worstall
    2017/02/05

    “Nordhaus has mostly argued for a small carbon tax, aimed at achieving a modest reduction in emissions, followed by sharper reductions in the medium and long term. Too much mitigation now, he has suggested, would damage economic growth, making us less capable of doing more in the future. This view has helped fossil fuel companies and climate change skeptics oppose any serious policy response.

    In his latest analysis, though, Nordhaus comes to a very different conclusion.”

    Well, yes, obviously. Because W. Nordhaus was saying we should have a nice low carbon tax back in the 1990s, one that would ramp up over time (from an all too fallible memory, from $10 a ton CO2-e to $250, yes, 250, not 25).

    And some of that time that should have been spent ramping up is now past and thus the correct level of the tax is higher.

    Yes, I know, he doesn’t actually say that but it’s an obvious thing that someone should say.

  12. #12 Hank Roberts
    at the reference desk again
    2017/02/05

    Surprise!
    ——————————————–
    Bathymetry of the Amundsen Sea Embayment sector of West Antarctica from Operation IceBridge gravity and other data

    First published: 4 February 2017
    DOI: 10.1002/2016GL072071
    Abstract

    We employ airborne gravity data from NASA’s Operation IceBridge collected in 2009–2014 to infer the bathymetry of sub–ice shelf cavities in front of Pine Island, Thwaites, Smith, and Kohler glaciers, West Antarctica. We use a three-dimensional inversion constrained by multibeam echo sounding data offshore and bed topography from a mass conservation reconstruction on land. The seamless bed elevation data refine details of the Pine Island sub–ice shelf cavity, a slightly thinner cavity beneath Thwaites, and previously unknown deep (>1200 m) channels beneath the Crosson and Dotson ice shelves that shallow (500 m and 750 m, respectively) near the ice shelf fronts. These sub–ice shelf channels define the natural pathways for warm, circumpolar deep water to reach the glacier grounding lines, melt the ice shelves from below, and constrain the pattern of past and future glacial retreat.

  13. #13 Hank Roberts
    at the reference desk again
    2017/02/05

    PS — so is anyone taking bets on what the _next_ IPCC Report will say about sea level rise? Or charting the trend in the IPCC’s forecasts over time? Perhaps we can predict the future. Or as Bradbury put it, “write not to predict the future, but to prevent it” — eh?

  14. #14 Hank Roberts
    P.S.
    2017/02/05

    I’m seeing more mentions of retreating as sea level rises. Note that every disaster increases the Gross National Product as all the cleanup and rebuilding adds to that total.
    https://www.google.com/search?q=climate+economics+retreat+coastal+remove+cleanup

    My concern is that we’re going to leave a lot of the New Intertidal Zone full of lead and oil and heavy metals and crap, and ruin the future usable productivity of the new oyster beds.

  15. #15 Russell
    2017/02/06

    11>
    And If tobacco taxes were less regressive, more smart people would have thought up more ways to outgrow carbon taxation long ago.

    Climate change is the mother of all two pipe problems

  16. #16 Dunc
    2017/02/06

    The question is how long is the long term, and how much should we care about the long term? I’m reluctant – as I’ve said before – to care about more than 100 years ahead. Because we can’t plan that far. Would it be useful to care about 1000 years in the future? Would we have thanked folks 1000 years ago had they attempted to care about us? -W

    This is the crux of the issue. 100 years really isn’t that long – if you plant trees, you routinely need to think in these sorts of terms, if not longer. As for whether we would have thanked folks 1000 years ago for caring about us, I’d say there’s a very good chance that we would if the topic had been “do we care about raising sea levels by several tens of meters and wiping all of our major cities off the map?” Note that while we have quite a few cities that didn’t exist a thousand years ago, all of the ones that did are still quite important, and it’s interesting to think what the last 1000 years of history would look like if they’d all been inundated.

    [I disagree. We would not have wanted people 1000 years ago to think of that – it would have been stupid, because they had no ability to do said inundation.

    But let’s imagine they took your advice, and started planning all their major cities to be at least 10 meters higher than they presently are. With all the attendant costs and therefore delay to development of civilisation. Would this have been a good idea? No, it would have been a very bad one -W]

  17. #17 Dunc
    2017/02/06

    We would not have wanted people 1000 years ago to think of that – it would have been stupid, because they had no ability to do said inundation.

    I’m obviously referring to some alternative history in which they did have such an ability… Additionally, I’m assuming that they were actively using it, and knew perfectly well that they were. In other words, I’m trying to make the analogy actually work, by placing those people 1000 years ago in a situation which is analogous to ours.

    Without this sort of modification, your question is silly, because people 1000 years ago simply weren’t able to modify the environment in really large scale ways that would have predictable (predictable by them, that is) negative effects over millennial timescales. But you can’t use the historical fact of that inability to argue that we shouldn’t act differently now that we are able to.

    [Yeah, sure. But simply giving them the ability by magic makes no sense.

    Try this way: given all that we know now, can we think of any useful way these people could have usefully thought 1000 years ahead? If the answer is “No. They could not” then why do you think we now could? -W]

  18. #18 Dunc
    2017/02/06

    Try this way: given all that we know now, can we think of any useful way these people could have usefully thought 1000 years ahead? If the answer is “No. They could not” then why do you think we now could?

    Once you have the ability to modify the environment on a really large scale, then there are things that you can do that you probably shouldn’t, and can predict well ahead of time. Personally, I feel it’s a pretty safe bet that inundating every major city on the planet is a very bad thing that we should try quite hard to avoid. A full-scale nuclear war would also fall into that category.

    [Yeeessss… the war doesn’t count, because (a) it is obviously bad and (b) requires no foresight to see as bad and (c) has immeadiate, not long term consequences. As for “inundating every major city on the planet” – well, think back to your person in AD 1000. Could they have conceived of the Thames barrier? No; it was waay outside any kind of engineering they could have thought of -W]

  19. #19 crandles
    2017/02/06

    >”[We would not have wanted people 1000 years ago to think of that – it would have been stupid, because they had no ability to do said inundation. -W]”

    True, but does it make a difference if we not only have the ability to do it in say 200-400 years but also sufficient understanding that it is a likely outcome as a result of our actions if we do not change our ways such that we do have responsibility for it?

    [I don’t think that current understanding is that 10+ m of SLR is likely in 200 years. I’m very doubtful of it in 400. Do you think otherwise? -W]

    Does responsibility not matter at all if it is more than 200 years hence and we don’t understand what the issues that will be pressing at that future time?

    [It is all a question of how we should use our finite resources of time, energy and effort. Should we think at least a bit about 1000 years from now? Yes of course. And indeed we do, when thinking about nuclear waste. Should we allow such considerations to dominate our plans for the immeadiate future even at the expense of our prosperity in that immeadiate future? Probably not. How do we find a sensible point of balance between those two? Probably by thinking about discounting -W]

    Perhaps it is more like if you hit someone who has a thin skull and is therefore particularly susceptible to brain damage. You are responsible for the damage caused even if you want to claim you were unlucky that the victim was so badly affected. So in assessing what might happen we have to consider possibilities of world being badly affected as well as possibilities of SLR not being much of a problem to future society. The chance of SLR only being a minor irritant seems low. Even if there is plenty of time for planned migration of cities, whenever and however slowly, it is highly likely to be costly not just a bit of a pain.

    If it was 90% certain to be no problem at all then not only should we discount future costs but it might be reasonable to apply a 90% reduction. However if there is significant risk of it being catastrophic then the future costs are likely to be much larger as a result of economy being larger at that future time so the discounting that is applied doesn’t really reduce it to negligible amounts.

    [I don’t think your last point really makes sense as you’ve put it together. “the future costs are likely to be much larger as a result of economy being larger” – but slowing economic growth so the economy is smaller so the future costs must be smaller because there is less to damage isn’t a sensible idea -W]

  20. #20 Phil Hays
    Looking ahead
    2017/02/06

    1000 years ago there was very little that could be done that would have a any impact 1000 years later.

    Now, there are many things we could do or are doing that will have significant impacts 1000 years later.

    The situations are different. Things have changed.

  21. #21 crandles
    2017/02/06

    >”[I don’t think that current understanding is that 10+ m of SLR is likely in 200 years. I’m very doubtful of it in 400. Do you think otherwise? -W]”

    Perhaps 10m is a bit high for 200-400 years but I think a lot of coastal cities would be in trouble with 3m SLR.

    http://www.realclimate.org/index.php/archives/2013/11/sea-level-rise-what-the-experts-expect/
    “With unmitigated warming, however, the likely range is 70-120 cm by 2100 and two to three meters by the year 2300.”

    Recent research seems to be finding more instability and more possible mechanisms for faster loss but maybe all that was known by experts in 2013 just not fully written up etc.

    >”[I don’t think your last point really makes sense as you’ve put it together. “the future costs are likely to be much larger as a result of economy being larger” – but slowing economic growth so the economy is smaller so the future costs must be smaller because there is less to damage isn’t a sensible idea -W]”

    Ideally you compare costs of reducing effect or impact current costs at current prices against future costs of damages discounted back to current £s. To get those future costs you might start with costs today but then inflate them for growing economy before deflating them back to today’s £s. If the deflate means it is just a few percent but the inflate figure is similar to inverse of deflate figure you can still end up with a significant amount for discounted back damages to compare against reduce effect / impact costs.

  22. #22 Chubbs
    Trumpsville
    2017/02/06

    After reading the paper I now know why they call economics the dismal science. Assuming I’ve done the numbers right, per this study fossil fuels are getting roughly a $1 trillion per year subsidy by not having to pay carbon taxes. This is estimated by multiplying the roughly $30 per ton social cost of carbon in 2015 times 35 B tons per year CO2 emissions. In the US alone the subsidy is roughly $200 B.

    [I don’t think that is a sensible way to think about subsidies. See for example http://scienceblogs.com/stoat/2015/05/18/fossil-fuels-subsidised-by-10m-a-minute-says-imf/ -W]

  23. #23 James Annan
    http://blueskiesresearch.org.uk
    2017/02/06

    1000 years ago (um…very roughly, ask a historian if you want a better number) people were actively and aggressively deforesting the UK, which has completely transformed our landscape.

    [Hmm,you might be wrong. https://en.wikipedia.org/wiki/Forestry_in_the_United_Kingdom#/media/File:Woodland_as_a_percentage_of_land_area_in_England.png says it went from 15% in 1000 to 5% in 1900 and up since then. That’s a factor of 3 decline, but much less in area; it was almost all gone by 1000 anyway -W]

    Whether that’s a good thing or a bad thing is very much a matter of debate, but I’m pretty sure they weren’t think of us when they were doing it.

    [Yes indeed. But, suppose they had thought of us and out tree-hugging ways? Would we have thanked them for staunchly defending tree cover at 15%, with the various lost opportunities that would have involved? -W]

  24. #24 James Annan
    2017/02/06

    ..but what I really meant to say was that you should have insisted on staying at stroke and rating 38 :-)

    [Pfft, these young folk. Don’t know when they have it good. Next leg of the winter league is this Sunday; perhaps we’ll hit 34 -W]

  25. #25 Kevin O'Neill
    United States
    2017/02/06

    Nordhaus: “This is also reflected in a major upward revision in the social cost of carbon (SCC) and the optimal carbon tax in the current period. For example, the estimate of the SCC has been revised upwards by about 50% since the last model.”

    Now, that’s what the author claims. TW notwithstanding, I tend to believe Nordhaus. He also supplies numbers in Table 2 on page 32. The baseline scenario does increase from $24 (DICE-2013R) to $37 (DICE-2016R) in constant dollars and for the same year. The 50% increase is from DICE-2013 to DICE-2016 and has nothing to do with estimates back in the 1990s. Worstall perhaps should have read the paper before commenting.

    Also of interest is that Nordhaus completely writes off the 2°C target and pretty much writes off 2.5°C. His optimum scenario results in a 3.5°C increase by the end of the century with a CO2 concentration of 625 ppm and shows no sign of decreasing temps going forward into the 22nd century.

    [N writing off the 2 oC target doesn’t amount to a change of views on his part, though. I commented on the “major” upgrade to SCC but his revision just puts him back into the same ballpark as others, so doesn’t seem that exciting -W]

  26. #26 Vinny Burgoo
    2017/02/06

    James Annan, more like late BC/earlyAD:

    https://pbs.twimg.com/media/BxcjfLBCMAA225i.png:large

    But it’s a valid point, or at least a point worth some serious chin-stroking. By today’s ethics, should they have cut down all the forests? No. Would today’s ethics (or interwebs) exist if they hadn’t? No.

    [Your pic rather resembles my graph (in that it is quite hard to see the change after 1000 AD in your pic -W]

  27. #27 Mal Adapted
    2017/02/07

    Russell:

    Climate change is the mother of all two pipe problems
    What’s in the other pipe, Russell ;^)? Tobacco wasn’t all Sherlock Holmes used to help him think!

  28. #28 David B. Benson
    United States
    2017/02/07

    With sufficiently elevated carbon dioxide concentration one expects 25 meters sea level rise in 1000 years. Simplifying, assume a sigmoid shape of the rise over the next 1000 years. So about 12.5 meters in 500 years. Thereby about 10 meters in 400 years.

  29. #29 David B. Benson
    2017/02/07

    About 1000 years ago the Norse were starting to be christianized. I suppose we all agree that was a Good Thing.

  30. #30 David B. Benson
    United States
    2017/02/07
  31. #31 Fergus Brown
    What rainbow?
    2017/02/07

    23-26: Deforestation was at first a matter of clearing land for agriculture and having fuel and building materials. Later, it was a matter of having material to build ships, from roughly the Tudors onwards. They experienced a shortfall and imported from the Baltic, realised the problem and started replanting.
    In the first case, they might argue that if they hadn’t developed agriculture they wouldn’t have flourished, in the second, that if they hadn’t built a Navy we’d all be speaking French, Latin, Spanish or something else by now – in other words, that their present need was meaningful both then and since.
    (which is roughly what W implies).
    It’s a mistake to think that earlier societies weren’t aware of the relationship between natural resources and both sustainability and growth, though they wouldn’t have used those words. The Roman Empire is a case in point; expansion was necessary to provide the needs of Rome, it wasn’t so much for the Glory. They had massive agricultural monocultures in Spain and North Africa (olive oil, wheat). Arguably, they understood the importance of water better than we seem to. Ninepence worth.

  32. #32 Phil Hays
    Americanistan
    2017/02/07

    #23 “deforesting the UK”
    If this was done in 1016, and the forests were not prevented from regrowth by continuous human actions, how could anyone to tell the difference by now? Only way I can think of might be missing species: New England was cleared about 1800, and the last known New England black oak died in the 1880’s. Is there anything similar in England forests? Extinction is forever, or at least until Jurassic Park(!). Deforestation of England was reversible on century time scales. At least mostly.

    An example might be soil erosion in drier climates. If the Greeks (and others) had practiced agricultural methods that prevent soil erosion, there still might still be productive farms where there are stony hills today. There are ruins of large villages that had populations over a thousand, that now serve as seasonal camp sites for a goat herder.

    Does the scale matter? If all of the farmland in the world had been eroded like this, what would the few goat herders left living in the ruins think about it?

    We are changes that will make the world much different for 10s of thousands of years. Closer to the soil erosion case, but on a global scale.

    “‘My name is Ozymandias, king of kings:
    Look on my works, ye Mighty, and despair!’
    Nothing beside remains. Round the decay
    Of that colossal wreck, boundless and bare
    The lone and level sands stretch far away.”

  33. #33 Corey
    2017/02/07

    (Mal, Holmes appears to have smoked tobacco almost exclusively; Gentlemen prefer cocaine by injection.)

  34. #34 Hank Roberts
    at the reference desk again
    2017/02/08

    http://bigstory.ap.org/article/c470f1b639c54f679b064e461d5086b9/gop-elder-statesmen-making-push-carbon-tax

    [Interesting. I’m tempted to say that now is not the time for this, but maybe -W]

  35. #35 Fernando L.
    Spain
    2017/02/08

    Nordhaus’ description of the work he did with DICE is here:

    http://cowles.yale.edu/sites/default/files/files/pub/d20/d2057.pdf

    If we refer to page 12, in the paragraph headed “decarbonization” we can read “the model has a highly condensed version of the energy sector”. I don’t have access to Dr Nordhaus, but I would like to point out that a dynamic model expected to forecast CO2 emissions ought to treat the energy sector in detail. Emissions reductions are dictated in part by government policies, population growth, changes in the size of economies, the cost of fossil fuels (ignoring externalities) and the cost of replacement energy sources.

    Please note that emissions have almost stabilized over the period 2014-15-16, even though oil and coal prices were in the lower part of the price cycle. This was driven in part by policy, but it was mostly due to market conditions. The key item to focus on is the significant drop in the cost of photovoltaic solar power, a slight improvement in energy storage costs, slight improvement in wind turbine costs, etc.

    Now we are entering a period of rebounding oil and natural gas prices, and we do know there’s a limit to reserves (this seems to be ignored by the dice model). The forces which “bent” the CO2 emissions to a much lower growth rate are still working. Therefore I must conclude the DICE model needs to be revised and gave a much more detailed and properly documented energy sector treatment.

    This flaw renders its results fairly useless for policy setting, and this means it’s fairly easy to overturn any policy decisions made using this particular model’s results.

  36. #36 Kevin O'Neill
    United States
    2017/02/08

    WC writes: [Interesting. I’m tempted to say that now is not the time for this, but maybe -W]

    LOL – why waste time on fantasies? I’ve reiterated that it ain’t happenin’. We might as well discuss whether climate fairies or climate gnomes are the best solution. All three have an equal likelihood — and that’s indistinguishable from zero.

    As Brad Plumer writes in response to these elder statesmen:

    "To date, exactly zero Republicans currently in Congress have publicly endorsed a carbon tax. On the contrary, last June, every single member of the House GOP voted for a resolution saying a carbon tax “would be detrimental to American families and businesses, and is not in the best interest of the United States.”"

    Does someone have a secret plan to change this reality?

    [https://www.congress.gov/bill/114th-congress/house-concurrent-resolution/89/text I think. Largely meaningless -W]

  37. #37 Hank Roberts
    at the reference desk again
    2017/02/08

    Thanks Kevin for the pointer to the Brad Plumer response at Vox. It’s full of useful links and cross-references.
    http://www.vox.com/energy-and-environment/2017/2/8/14547290/conservative-carbon-tax

  38. #38 Eli Rabett
    http://rabett.blogspot.com
    2017/02/08

    Since the damage function in DICE is pulled right out of nowhere, no. Eli is not impressed

  39. #39 Eli Rabett
    http://rabett.blogspot.com
    2017/02/08

    See Pindyk pg 6

    But remember that this damage function is made up out of thin air. It isn’t based on any economic (or other) theory, orany data. Furthermore, even if this inverse-quadratic function were somehow the true damage function, there is no theory or data that can tell us the values for the parameters π1 or π2, or the correct probability distributions for those parameters, or even the correct means and variances.

  40. #41 Eli Rabett
    http://rabett.blogspot.com
    2017/02/08

    Like P or not, what he says about Nordhaus’ damage function is true, it’s not even mangled models like FUND

New comments have been temporarily disabled. Please check back soon.