Suppose you believe, as many people do, that climate change due to anthropogenic CO2 is a serious problem. There are two different ways you might try to deal with it. One is by trying to keep it from happening, or at least to slow it. The other is by adapting to it. There are at least two respects in which the latter approach is superior to the former.
The first is that it avoids the public good problem. If the U.S. switches to more expensive sources of power in order to hold down CO2 output, any benefit from reduced warming is shared with the rest of the world. It is unlikely to happen unless either the benefit is so much larger than the cost that it is worth doing for the U.S. share alone or many countries manage to coordinate their policies, despite the obvious temptation for each to free ride on the efforts of the others. Neither is impossible, both are difficult.
Adaptation does not face that problem. If Bangladesh deals with sea level rise by diking its coast, the benefit goes to Bangladesh, not to the U.S. or China. If a farmer deals with an increase in temperature by shifting to a crop better suited to the new conditions, he gets the benefit.
The second advantage of adaptation is that it affects only the negative consequences of climate change. While the public discussion often obscures the fact, there are positive consequences as well—indeed, it is not clear that the net effect is negative, especially at low levels of warming. Milder winters are, on the whole, a good thing. So are longer growing seasons. So is an expansion of the habitable area of the northern hemisphere, due to temperature contours shifting north. A reduction in warming eliminates the good consequences as well as the bad. Adaptation can target only the bad consequences.
Neither of these proves that adaptation is superior—that depends on the costs of adaptation, the costs imposed by warming, the benefits imposed by warming, the costs of reducing warming. But both are arguments in favor of adaptation.
33 comments:
David, you continue to ignore the inter-generational component of the public good problem.
There is simply no justification for taxing living people, many of whom have already contributed to the global warming solution by not breeding, in order to enhance the life of the breeders' progeny.
For that reason, your coping solution is much superior: it puts the burden on those who will benefit, not on past generations of conscientious non-breeders.
Societies full of non-breeders and other degenerates will be overtaken sooner or later by a society willing to have children, or willing to do other activities which further their nation or race.
I admit, I am a bit flabbergasted by this comment. You mention the public goods problems, but seem to fail to see the inverse commons problem: per-capita CO2 emissions of Bangladesh are negligible compared to those of the US. But while the US does not share output of the economic activity that causes emissions, its externalities are shared around the world - and any map accounting for vulnerability (thus accounting how physical impacts translates into e.g. output loss) will show you that this share is not even equitable. I.e. the US would bear less than their fair share of (gross) damages (a similar argument is to be made for most of Europe).
Also, it is an odd argument to say that a small amount of warmning might be beneficial. This is not policy relevant. Carbon taxes are based on the social cost of carbon (SCC), which is a marginal concept. The little warming we have seen to far, and quite a bit that is still to be expected, are built in: these are "sunk" costs. Further emissions inflict almost certainly a cost - try to find a serious assessment that says otherwise - for decades. That is, marginal costs are positive, and they are the quantity relevant for policy, isn't it?
Martin, are you arguing that Bangladesh would be somehow better off if the world had never industrialized and emitted CO2? And if so, that there is something unfair about their lack of development? What could be more fair than having sea level rise equally around the world?
"That is, marginal costs are positive, and they are the quantity relevant for policy, isn't it?"
Marginal costs are relevant, but it isn't at all obvious that they are positive. Richard Tol's JEP article surveying the economic literature has a graph (figure 1) showing the estimated effect of temperature increase relative to the present, based on fitting the various studies. The fitted line shows marginal benefit up to about one degree. The 95% confidence interval range includes marginal benefit up to about two degrees.
The figures I've seen on the current IPCC estimates look like about 2 degrees or a little more, depending on details, relative not to current temperature but to an average over the period before current warming started. That's not much more than one degree relative to current temperature. Tol's piece is at:
http://pubs.aeaweb.org/doi/pdfplus/10.1257/jep.23.2.29
So no, it's not obvious that marginal cost is positive for further small increases.
"You mention the public goods problems, but seem to fail to see the inverse commons problem"
On the contrary, we are talking about the same problem. Your point is that the existence of a public good problem means that less of the public good (CO2 reduction) will be produced than would be if the decision was made by a wise and benevolent social planner.
My point is that, since the world is not run by wise and benevolent social planners, the issue is not what they would do but what we will do. Trying to persuade people to produce a public good that it is not in their interest to produce is a less effective strategy than persuading them to achieve a similar end by producing a private good that it is in their interest to produce.
"the US would bear less than their fair share of (gross) damages"
At this point you seem to be confusing economics with moral philosophy. The public good problem would still exist if costs and benefits were evenly shared, since each actor is bearing all of the costs of his reduction in CO2 output and getting only a fraction of the benefit.
@ Roger
Much would be gained if people would read an intro textbook and not get confused about total and marginal quantities. That a glass of wine may have a positive effect does not mean that every further glass of wine is beneficial. Indeed, it tells you absolutely nothing about any further glass of wine - though I think we'd agree that at some point, a further glass is harmful.
That a certain amount of warming is beneficial tells you absolutely nothing about the effects of further warming. Which brings me to
@ David Friedman
This is flatout untrue. Figure 1 in your references paper reports TOTAL costs, not marginal costs. This you can easiliy tell by just realising that this figure is in the section "Estimates of the Total Economic Effect of Climate Change." Even more intriguingly, in the text, Tol says, firstly, what I said:"The initial warming can no longer be avoided; it should be viewed as a sunk benefit." This initial warming cannot be avoided: it is policy irrelevant, as every econ101 book exaplains approx. in the introduction. Second, I quote - and referring to this exact figure:"In short, even though total economic, effects of 1–2°C warming may be positive, incremental impacts beyond that level are likely to be negative. Moreover, if one looks further into the future, the incremental effects look even more negative."
So, even if you look at total cost estimates, you can tell that an incremental increase will produce a cost - by simply looking at the curvature of the total cost function and how much warming we have already built into the system.
But there is another section, "Estimates of the Marginal Cost of Greenhouse Gas Emissions." Now, here the mean - as the text says - might be a bad guide: it is pushed toward high numbers by a few extremely high estimates. But even looking at modal estimates, there is littme doubt that that the marginal cost is positive (see table 2 and accompanying text). There is very bad evidence as how high SCC are - from looking at the literature - but that they are positive is, according to the very paper you reference, not really in doubt.
Also, here is the final sentence of the paper:
"There is a strong case for near-term action on climate change, although prudence may dictate phasing in a higher cost of carbon over time, both to ease the transition and to give analysts the ongoing ability to evaluate costs, benefits, and
policy mechanisms."
A more up-to-date literature overview by the same author is here, btw.:
http://ideas.repec.org/a/eee/dyncon/v37y2013i5p911-928.html
Is there a policy that, if enacted worldwide (obviously this is hypothetical) would correctly incentivize people to either adapt to climate change or to prevent it by emitting less CO2? I guess any perfectly constructed carbon tax would have to look at the costs of climate change with adaptation, as opposed to the costs of climate change without.
"the US would bear less than their fair share of (gross) damages"
David,
I don't think this was Martin's argument, but the fact that some countries receive more than their fair share of damage will actually diminish the public good problem. If only a few countries were harmed, but harmed greatly, then those countries would constitute a privileged minority, which could solve the public good problem more easily.
In the extreme, if one country suffered all the harm, the public good problem would disappear (assuming nations can be treated as individuals), since that nation could unilaterally pay other nations to reduce carbon emissions. The problem with the typical global warming hypothesis that is advanced is that the harm it postulates is too evenly distributed. If it were more unfair, it would be easier to solve.
Let's go Dutch;
http://www.dw.de/floating-houses-to-fight-climate-change-in-holland/a-17532376
"We shouldn't see water as a danger, but as a chance, as a challenge."
@ David Friedman
Yes, I am talking about a moralphilosophical argument - but a pretty mainstream one: it's standard utilitarian assumptions. If you have economic agents, of which the rich ones produce an externality that damages the poor ones - and then you plug this all in a welfare theoretical framework, you'll NOT assume that consumption-utility is not concave. The curvature of the consumption-utility function will of course enter the discount rate via the the elasticity of the marginal utility of consumption. This is not something I made up.
Note that in the case of the non-zero probability that climate change drives down regional (!) economic activity to subsitance level, "the discount factor goes to infinity, taking the marginal costs with it." That is, as long as you do not give zero weight to that region/country. Again, this are standard welfare-theoretic assumptions, not some moral philosophical tinkering. As long as your utiliy function is concave, this has very real consequences, as SCC is the discounted net-present value of damages in the (infinite) future of an incremental increase in emissions now.
The finding about infinite marginal costs is by whom? Again, by the infamous doomsayer Richard Tol, in what he now calls a "precursor" to Weitzman's Dismal Theorem about the implications of a fat tailed climate sensitivity:
http://link.springer.com/article
@Martin: Any argument of harm to Bangladesh is highly speculative, whether looking at total or marginal quantities.
Your article is behind a paywall and I did not read it. Your quotes are enough to show that the paper is just a slanted political opinion, and does not have any serious economic analysis.
@ Roger
There seem to be a series of misunderstanding, and perhaps I am just not clear enough.
None of these are "my" articles: David Friedman himself quoted a literature overview by Richard Tol that has statistics over all literature estimates of total economic impact and marginal economic impacts (i.e. SCC) of global warming (at the time of publication). He disputed my claim that there is really very little space for the claim that marginal cost of CO2(e) emissions is negative by pointing to the TOTAL cost estimate. This is simply wrong, period. Now, I do not think that he does not know the difference between total and marginal cost, and if I had to guess, I'd say what he meant is something like the marginal cost of warming. But as the same paper points out (and me too, above), the warming that might have a net-beneficial impact is very likely built into the system by what we have already emitted - it is not policy-relevant. SCC - on which a Pigovian tax would be based - is NOT the marginal cost of warming, but of emission; this is not the same thing. It is OK to feel that the paper is nonsense, but one cannot reference it as evidence that there is any serious doubt about the sign of the SCC. Though, I might add, both the earlier and the more recent literature overview are simply statistics on the literature: there is not much room for "slanted political opinion."
The Bangladesh issue was used by all here as a synecdoche, if I am not mistaken, for a country that adapts to impacts of AGW, specifically sea-level rice. Professor Friedman says that adaption has the distinct advantage (over mitigation) that a country that adapts in a specific way reaps the benefits of this adaption, while a tax is vulnerable to the free-rider problem. This overlooks that this alleged "benefit" is really just "avoided damage" - a damage that is caused by a global externality that is overwhelmingly NOT produced by "Bangladesh". Still, "Bangladesh" has to divert resources from whatever it would like to do to adapt to a problem it has not caused, while the "US" (again, a synecdoche), who causes it, inflicts the damage. Now, this is allegedly just my confusion between economics and moral philosophy - though I'd submit that there simply is no welfare economics withouth moral philosophy, so I don't really get the point. If I dumped dimethyl mercury into your backyard, and you have to bear the costs (either by dying, or by cleaning it up), one can certainly find some framework where this is OK - though I'd say the burden of argumentation is on the one who feels this is OK. Anyway, if you take me, the mercury dumper, and you, the mercury bearer - and look for a (potential) Pareto optimum, I almost certainly won't be able to simply proceed as it is. Or perhaps I would. Point is: literature says w/r/t greenhouse gas emissions that we can not: we should tax them, as they inflict a net damage. Taking the damaged out of the equations is of course a neat way to not have an externality - though, in this case, one might as well argue that there is no such thing as an externality.
"Point is: literature says w/r/t greenhouse gas emissions that we can not: we should tax them, as they inflict a net damage."
Let's assume that Richard Tol's central line in Figure 1 of this paper is accurate:
http://www.sciencedirect.com/science/article/pii/S0165188913000092
Let's further assume that the temperature increases throughout the 21st century, such that the temperature in 2100 peaks at about 1.5 degrees above the "zero" point of his curve. And then let's assume that the temperature no longer increases, because the world of 2100 has reduced CO2 emissions to essentially zero.
In that scenario, where do fossil fuel emissions inflict a net damage?
@ Mark Bahner
I don not quite understand why everybody is obsessed with this figure 1 ever since Ridley (or was it Watts?) has talked about it. Reading the paper is obviously not required to produce one's own phantasy interpretation of that figure.
The figure is about total costs. Total costs can be negative (a benefit) even though marginal costs are positive. There is absolutely no contradiction here. I don't know what's so difficult about this: if you take the function f(x) = -x^2+4, the function is positive from x in ]-2,2], but it's derivative is negative from zero onwards. No contradiction. Now, with regard to figure 1, we are already past the maximum of that curve (these benefits are sunk): any further emissions bear more costs than benefits, and should be taxed accordingly, so the standard implication. That is, from where we are, any further emissions bear out a net cost - if we only forgo the total benefit perhaps accrued before, or if we turn even the total negative, is another question. The point is that, from where we are, it slopes downwards, hence a tax - which is the very conclusion of the paper!
"Figure 1 in your references paper reports TOTAL costs, not marginal costs. "
Correct, except that it is total economic impact--positive numbers are benefits. As you can see looking at the graph, the benefit is increasing up to about one degree on the central line, meaning that the marginal benefit is positive, meaning that the marginal cost is negative. It's increasing up to about 2 degrees on the top line, the boundary of the 95% confidence interval.
You quote Tol as saying: ""There is a strong case for near-term action on climate change"
Yes. I wasn't claiming that he disagreed with that position, although I do. I was pointing out that, contrary to what you wrote, further emissions might be beneficial.
Suppose, for a moment, that we have a rate of emissions that gives us 2° warming by 2100. Further suppose we choose to ignore effects beyond that, whether to simplify my point or because, as I believe, any prediction that far ahead is almost worthless due to radically uncertain implications of technological change. Finally, assume that marginal benefit is positive up to one degree, negative from there to two, total benefit at two degrees zero.
I interpret figure 1 as showing the effect in a year, relative to GDP, of a given level of temperature in that year.
An extra ton of carbon put into the atmosphere makes us worse off in 2100. But it makes us better off in 2015-~2055, because through those years we are still in the region where additional warming produces a marginal benefit and the extra ton gives us our extra warming sooner. So to get the overall effect over the rest of the century of adding that extra ton you have to integrate the marginal effect.
Looking at the central line of Figure 1, the integral should be about zero, ignoring complications associated with the pattern of warming that gets you from zero to 2 degrees. So whether marginal effect of an extra ton is positive or negative is an open question.
"This overlooks that this alleged "benefit" is really just "avoided damage" - a damage that is caused by a global externality that is overwhelmingly NOT produced by "Bangladesh". "
I do not see the relevance of that to my point. Because the benefit of diking is a private good (to Bangladesh, which at this point I am treating as if it were a single rational actor) it gets produced. Because the benefit of slowing warming is a public good, it does not get produced. That's an economic point not a moral point, and welfare economics is irrelevant to it.
You seem to be imagining that I am offering arguments to a benevolent despot capable of giving everyone in the world orders and having them obeyed. In that context the first point in my post would be irrelevant, although the second would not be. I thought that style of economic analysis, what some of us referred to as the philosopher king approach, had gone out of fashion some decades back.
@ David Friedman
No, please red the paper, you cannot just invent the point it is making. Tol clearly states - in the section - that marginal costs are positive.
Again, you confuse marginal cost of further warming with marginal cost of further emissions. The warming you mention is built in. It is sunk, for the fourth time, or so - and the paper states so explicitely. The is nothing we can do to avoid it. Further emissions cause warming well beyond the warming that is already built in. Its expected marginal cost is positive.
Please read the paper! I even referenced the table!
Martin:
You write, "I don not quite understand why everybody is obsessed with this figure 1 ever since Ridley (or was it Watts?) has talked about it."
Well, I don't know about "everybody," but I read original paper and figure when Richard Tol referred to it on Roger Pielke Jr.'s blog. It's an error in logic for you to assume you know me just because you know "everybody."
"Now, with regard to figure 1, we are already past the maximum of that curve (these benefits are sunk): any further emissions bear more costs than benefits,..."
How do you figure that? We are *not* at 1 degree Celsius warming in that figure. We're at whatever warming is "in the pipeline"...which Hansen et al. estimated in 2000 as 0.4-0.5 degrees Celsius:
See 9876, "Consistency Checks"
"The warming you mention is built in."
Nobody expects temperature to be a degree higher next year than this year. Agreed?
If marginal benefit of warming is positive between zero and one degree, then additional emissions at this instant, resulting in additional temperature next year, produce a benefit for next year as well as some combination of benefits and costs in later years.
Agreed?
The CO2 currently in the atmosphere will produce some amount of additional warming over the next few centuries. Even if we assume that it will eventually take us to a global temperature at which further warming has negative marginal benefit, that doesn't tell us what the sign is of the integral from now to infinity of the annual benefit from the effect of the increase in temperature due to an extra ton of carbon in the air now.
That depends on lots of additional assumptions about what happens in future years.
So far as current IPCC estimates are concerned, I find:
"Global temperatures averaged over the period 2081–2100 are projected to likely exceed 1.5°C above 1850-1900 for RCP4.5, RCP6.0 and RCP8.5 (high confidence), are
likely to exceed 2°C above
1850-1900 for RCP6.0 and RCP8.5"
Current temperature is about .8° above 1850-1900, so they expect additional warming of a degree or so by 2100, depending on emissions. They expect more than that after 2100--but I've already given my reason for not giving much weight to that.
@ Mark Bahner
OK, let's make that short, I've had my share of people pretending to be dense here.
The paper referenced has an overviey about social cost of carbon estimates of the entire literature up to publication date. The median of this cost is positive. Thus, the statement that there is any doubt about the sign of SCC is flat-out wrong.
That is all.
@ David Friedman
For you, too. You actually have the chuzpah to reference a paper for a claim that there is doubt concerning the sign of the SCC that actually has a whole section - with the corresponding subtitle - telling you that this is simply not the case.
Your reasoning is faulty, and the paper points out why.
Could you please read the paper, after all?
There is plenty of doubt about the sign of SCC. You just cite some nonsensical political rant with silly arguments about "Estimates of the Total Economic Effect of Climate Change." There is no such thing as an economic effect of climate change. The climate has always been changing, and always will be changing. It is like estimating the cost of the Sun shining. The paper tells us nothing about the social cost of carbon.
@ Roger
Well, OK, at least that's a coherent position: you believe that the whole literature on the physics of climate change and its economic consequences is plain wrong, from A to Z.
But that is very different from referencing a paper for the claim that there is doubt about the sign of marginal impacts of emissions when this very paper has a whole section "Estimates of the Marginal Cost of Greenhouse Gas Emissions" that points out that this is really not the case.
I am not rejecting any scientific papers on climate change. I do reject papers on the "cost of climate change" because they assume that all change is bad.
Anonymous (presumably "Martin") addresses me as follows: "OK, let's make that short, I've had my share of people pretending to be dense here."
It's very curious that you could write about "people pretending to be dense" when you apparently can't even discern the slope of a curve.
On second thought, I guess there are at least two other possibilities:
1) I guess you could be vision-impaired; but if so, you really should get help before you insult others.
2) Or I guess you could be ignorant, and not know where we are on the curve. As I wrote previously, we are *not* at the peak of the curve, which peaks at 1 degree Celsius *above* "today" (the paper was published in May 2013). But in that case, since you’re ignorant, and so shouldn't accuse people who don't share your ignorance of "pretending to be dense."
You previously wrote, "Now, with regard to figure 1, we are already past the maximum of that curve (these benefits are sunk): any further emissions bear more costs than benefits,..."
That is simply wrong, and I challenge you to put your money where your big fat keyboard is. I'll try to bring Richard Tol to comment on your sentence: "Now, with regard to figure 1, we are already past the maximum of that curve (these benefits are sunk): any further emissions bear more costs than benefits,..."
If he says the sentence is correct, I'll give you $50. If he says the sentence is wrong, you give me $200, and write on this blog, "My name is Martin. I should not accuse people of "pretending to be dense" when I'm writing about things of which I'm ignorant."
How about it? You obviously think you're pretty hot stuff, so this bet shouldn't be a problem for you.
Sincerely,
Mark
@ Roger
I stand corrected. So you reject the notion that climate change could have any cost and that the whole literature on the issue is nonsense. This is a coherent position.
@ Mark Bahner
Yes, my fault, that was indeed me. Tol has already addressed the issue in that he has written the paper. Here is what he says explicitly about figure 1 IN THE PAPER (references omitted):
"The initial warming can no longer be avoided; it should be viewed as a sunk benefit. The fitted line in Figure 1 suggests that the turning point in terms of economic benefits occurs at about 1.1°C warming (with a standard deviation of 0.7°C). Policy steps to reduce emissions of greenhouse gases in the near future would begin to have a noticeable affect on climate sometime around mid-century—which is to say, at just about the time that any medium-run economic benefits of climate change begin to decline."
You, too, could try to read the paper, instead of eyeballing and guesstimating a graph. When you and Professor Friedman have done so, please let me now.
As an aside, it was quite silly of me to get into this futile exercise of guessing marginal emission cost from figure 1. That is not how SCC are calculated, which, again, can be read about in the section "Estimates of the Marginal Cost of Greenhouse Gas Emissions" of the very same paper. Of course, the whole thing springs out of an explicitly utilitarian framework, which is another thing people here are simply not aware of.
Martin has the "chutzpah" to tell me: "You, too, could try to read the paper, instead of eyeballing and guesstimating a graph. When you and Professor Friedman have done so, please let me now(sic)."
I read the paper when you first referred to it on March 31st. Apparently you hadn't, or you wouldn't have made the comment, "Now, with regard to figure 1, we are already past the maximum of that curve (these benefits are sunk): any further emissions bear more costs than benefits,..."
So let's move on. Now that you've hopefully stopped making such statements, please go back and answer my question of March 31st:
Assume that the central line of Tol's Figure 1 is accurate. Let's further assume that the temperature increases throughout the 21st century, such that the temperature in 2100 peaks at about 1.5 degrees above the "zero" point of his curve. And then let's assume that the temperature no longer increases, because the world of 2100 has reduced CO2 emissions to essentially zero.
In that scenario, when do fossil fuel emissions inflict a net damage?
I guess a second question would be "Under such a situation, what is the estimated social cost of carbon in 2014, assuming a discount rate of 4%?"
Mark writes:
"then let's assume that the temperature no longer increases, because the world of 2100 has reduced CO2 emissions to essentially zero"
As I understand it, reaching the equilibrium temperature for a given level of CO2 takes quite a long time, so if CO2 levels stabilize in 2100 temperature will continue to rise for some time thereafter.
So to make your example work, you probably want to assume that in 2100 there is a technology that lets us inexpensively pull CO2 out of the atmosphere to get it down to the level at which the temperature in 2100 is the equilibrium temperature.
@ Mark Bahner
No, Mark, I stand by my statement - it is exactly what the paper says. The maximum of that total cost curve is built in in what is emitted. Further emissions will bear out a net damage. Of course, these are marginal damages, to which I referred - literally - when saying: "any further emissions bear more costs than benefits." That's exactly what a marginal emission damage is: the damage caused by further emissions (in the case of SCC of a ton). You seem to believe that it must be total damages when one says "net." But that is just confusion on your part.
You are simply confused about the difference total and marginal damages. This really seems to be a problem here.
Also, it was not me who referred to this paper, but Professor Friedman.
I just don't get why anyone accepts the premise that an increase in CO2 is bad for the planet? Or that it is caused by man's activities? Is there any HARD evidence that is the case?
Is CO2 not what we put in greenhouses to make plants grow better? Is it not what we breathe out with every breath? Has the CO2 level not been many levels higher in the past like during the last ice age?
I mean we have to take into consideration that the people writing these reports are essentially paid by the government through government grants don't we? If you were dependent on government money wouldn't you make sure to produce the report that they want? The powers that be want a global government that can impose carbon taxation and other international taxes upon the populations of the world. This is their way of doing so. You are helping them achieve their goals by buying into their obvious lies.
I have heard other "theories" that Planet X or Niburu is the culprit for the rising sea levels in Bangladesh? In my opinion this "theory" is just as valid as what the governments of the world are pushing in order to implement another level of taxation aka theft upon citizens of the planet.
I might be willing to research what you all seem to assume is true that climate change is manmade if the solution were not another tax. Since when has any government collecting more money solved any problem? Seriously - give me just one example?
Al Gore is a very rich man today because he was able to convince many people that mankind is a scourge upon this planet. I'm sorry, I see that as a defeatist attidue, I know that mankind is capable of reaching to the stars if we could just get past all of the made up problems.
Does anyone here realize that the world economy is on the brink of collapse? Does anyone understand that Russia and China are moving to take the world off of the petrodollar which would increase the costs of gas and food in the US exponentially?
I honestly believe that they put these make believe problems out there and get us arguing about them so that we don't focus on the real issues, the gradual enslavement of the human race by very rich, very smart dedicated people. Elesium anyone? Anyone heard of a book called 1984? If authors could foresee this type of tyranny 50 years ago, don't you think we should be paying attention to what they said as their predictions start to come true?
Maybe I'm missing something but I just don't get it. I understand that the people commenting and writing this article are very smart people whose heart is in the right place, but have any of you considered for one moment that you are being conned?
Just asking...
J
Divided we fall, united we stand, don't let them keep dividing us.
Hi David,
You write, "As I understand it, reaching the equilibrium temperature for a given level of CO2 takes quite a long time, so if CO2 levels stabilize in 2100 temperature will continue to rise for some time thereafter."
Conventional wisdom, per the Hansen et al. paper to which I referred previously (March 31, 6:11 PM), is that there is 0.4-0.5 degrees Celsius "in the pipeline."
So let's change the scenario...the temperature rises by an average of 0.17 degrees Celsius per decade from 2000 to 2050. That's 0.85 degrees Celsius higher than 2000 by 2050. Then it rises by 0.65 degrees Celsius more from 2050 to 2100. That's 1.5 degrees Celsius higher than 2000 in 2100. Then it rises 0.1 degree Celsius per decade for the next 5 decades (even though the additional radiative forcing stopped before 2100). So the total warming is 2.0 degrees Celsius above the value in the year 2000.
Let's further posit that the total emissions of carbon in the 2000 to 2100 period is about 700 gigatons of carbon, with virtually all occurring in the 2000-2070 timeframe. So let's say the average for the decades is:
2000-2010: 90 GtC
2010-2020: 110 GtC
2020-2030: 150 GtC
2030-2040: 130 GtC
2040-2050: 110 GtC
2050-2060: 80 GtC
2060-2070: 30 GtC
2070-2080: 0 GtC
2080-2090: 0 GtC
2090-2100: 0 GtC
Assume an annual world GDP growth rate of 4% for the period 2000-2200.
With a discount rate of 4%, and a response to GDP exactly as in the Tol paper bolded centerline, what is the calculated social cost of carbon in 2014?
I don't expect Martin to ever come up with a numeric estimate for this scenario, so unless you do, I'll have to come up with an estimate myself. I'll be extremely surprised if the calculated social cost of carbon in 2014 under this scenario is a positive value. :-)
Mark
"Adaptation can target only the bad consequences."
I'm only picking nits, here, but this statement kind of bothers me.
Of course adaptation can target good consequences, but no rational person would deliberately seek to minimize the good consequences without a compelling reason for doing so, such as a coercive government policy or an alternate beneficial result that was equal to or better than the good consequences from global warming.
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