Friday, May 22, 2009
Is the IPCC Saying What I Think It's Saying?
(UPDATE below.)
Ever since I tackled Joe Romm's argument (in which he is just reproducing the IPCC's own statement) of how "cheap" it will be to stabilize greenhouse gas (GHG) emissions at safe(r) levels, I have been trying to dig up the IPCC's estimates of future GDP losses from climate change in the absence of new government policies.
You see, the trick the IPCC used to downplay the cost of the policies, was to convert large future reductions in the level of GDP (relative to baseline) into a lower annualized growth rate. So for example, the high-end estimates are that GDP in 2050 will be up to 5.5% lower because of policies that governments put in place to curb GHG emissions. But that works out (at the time of the IPCC AR4 report) to only a 0.12% reduction in annual GDP growth, which doesn't seem like a big deal. Who but shareholders of Big Coal would object to that?
So what I wanted to do was the same trick. Even the really scary projections of huge damages from business-as-usual don't kick in until after 2100. So for example, let's say that if we continue on our suicidal path, that global GDP in the year 2150 is 50% lower than it would be, if there were no such thing as the greenhouse effect. (Well, if there were no greenhouse effect we'd all freeze I think, but you get what I'm saying.)
OK now that's pretty severe; I'm considering a scenario where literally half of the entire earth's productive capacity is destroyed because of our destructive emissions. Now it's true, some of the possible damages are unquantifiable; but if we're going to go through the farce of a cost/benefit analysis, then we have to come up with a number. So to repeat, I don't think I'm being a "denier" or a "skeptic" by discussing a case in which half of global GDP gets wiped out by 2150.
Yet using the IPCC trick, that works out to only a 0.5 percentage point reduction in growth rates. For example, if real GDP would have grown at 3% annually in the absence of climate damage from unrestrained emissions, then the "inconvenient truth" of anthropogenic global warming means real GDP will grow only at an annualized rate of 2.5% between now and 2150. Over that course of time, the gap between the two GDP series will have grown to 50%.
So even in this fairly nightmarish scenario, it means that someone who earns $10,000 per year today, would earn "only" $325,000 per year, in 2150. (Actually it's less because of population growth, but you get the idea.) In contrast, were it not for the inconvenient truth of climate change, this representative person would be earning twice as much, i.e. $646,000 per year, in 2150. (My spreadsheet is rounding the numbers.) It is to avoid the nightmare scenario of condemning our great-great-...-great-grandchildren to earning only $325,000 per year, that we must immediately hand over the energy sector to the federal government.
=======================
But I digress. As you can see from the discussion above, it would take some pretty fantastic projections of GDP losses in the distant future, in order to make immediate action seem necessary for any cost/benefit test that isn't completely rigged. (By completely rigged, I mean one that says, "The risks of doing nothing are essentially infinite, so any mitigation policy is justified.")
Yet I was having real trouble finding the IPCC's numbers. I know what Nordhaus' DICE model says, but that's because I've been studying his model thoroughly. In contrast, I hadn't examined the Second Working Group report of the AR4; I had focused mainly on WGI's discussion of the physical science of climate change.
But look what I just stumbled upon, from the overall Synthesis of the AR4. This comes from the 3rd last paragraph in the entire summary [.pdf]. Is this saying what I think it's saying? Seriously, those of you who are big fans of the IPCC--or at least, who think that the "deniers" and "skeptics" are making mountains out of molehills--please explain the following paragraph.
I think we can all see now why Joe Romm et al. are taking such pains to ridicule the very notion of applying a cost/benefit test to climate policies.
UPDATE: OK I think that the IPCC statement really is poorly worded. I just waded through Chapter 3 of the AR4 Working Group III book, and I didn't see anything about comparing abatement costs with the benefits of avoided climate damage. (Nordhaus does this very clearly in his book discussion [.pdf] of the latest DICE model results.) What I did see was a discussion showing that the range of estimated prices for carbon emissions (under various policies like cap and trade) roughly overlapped with the estimated values of the "social cost" of carbon emissions.
I'll post more on this stuff later in the week, but for now let me just say that this isn't at all what the quotation above is saying. In the absence of enforcement costs and other frictions, the optimal policy would set the price of emitting a ton of carbon equal to its social cost. But even though this would equate the (marginal private) cost with the (marginal social) benefit, it's not true to say the "costs and benefits" of this policy are the same. On the contrary, there would be large net benefits because emitters would scale back their output of GHGs to the socially optimal point.
Rereading the IPCC quotation, I am still not sure what's going on. Surely they wouldn't have let some non-economist write the summary, right? And yet, they are clearly saying that the policies don't yield net benefits. Hmmmm.
Ever since I tackled Joe Romm's argument (in which he is just reproducing the IPCC's own statement) of how "cheap" it will be to stabilize greenhouse gas (GHG) emissions at safe(r) levels, I have been trying to dig up the IPCC's estimates of future GDP losses from climate change in the absence of new government policies.
You see, the trick the IPCC used to downplay the cost of the policies, was to convert large future reductions in the level of GDP (relative to baseline) into a lower annualized growth rate. So for example, the high-end estimates are that GDP in 2050 will be up to 5.5% lower because of policies that governments put in place to curb GHG emissions. But that works out (at the time of the IPCC AR4 report) to only a 0.12% reduction in annual GDP growth, which doesn't seem like a big deal. Who but shareholders of Big Coal would object to that?
So what I wanted to do was the same trick. Even the really scary projections of huge damages from business-as-usual don't kick in until after 2100. So for example, let's say that if we continue on our suicidal path, that global GDP in the year 2150 is 50% lower than it would be, if there were no such thing as the greenhouse effect. (Well, if there were no greenhouse effect we'd all freeze I think, but you get what I'm saying.)
OK now that's pretty severe; I'm considering a scenario where literally half of the entire earth's productive capacity is destroyed because of our destructive emissions. Now it's true, some of the possible damages are unquantifiable; but if we're going to go through the farce of a cost/benefit analysis, then we have to come up with a number. So to repeat, I don't think I'm being a "denier" or a "skeptic" by discussing a case in which half of global GDP gets wiped out by 2150.
Yet using the IPCC trick, that works out to only a 0.5 percentage point reduction in growth rates. For example, if real GDP would have grown at 3% annually in the absence of climate damage from unrestrained emissions, then the "inconvenient truth" of anthropogenic global warming means real GDP will grow only at an annualized rate of 2.5% between now and 2150. Over that course of time, the gap between the two GDP series will have grown to 50%.
So even in this fairly nightmarish scenario, it means that someone who earns $10,000 per year today, would earn "only" $325,000 per year, in 2150. (Actually it's less because of population growth, but you get the idea.) In contrast, were it not for the inconvenient truth of climate change, this representative person would be earning twice as much, i.e. $646,000 per year, in 2150. (My spreadsheet is rounding the numbers.) It is to avoid the nightmare scenario of condemning our great-great-...-great-grandchildren to earning only $325,000 per year, that we must immediately hand over the energy sector to the federal government.
But I digress. As you can see from the discussion above, it would take some pretty fantastic projections of GDP losses in the distant future, in order to make immediate action seem necessary for any cost/benefit test that isn't completely rigged. (By completely rigged, I mean one that says, "The risks of doing nothing are essentially infinite, so any mitigation policy is justified.")
Yet I was having real trouble finding the IPCC's numbers. I know what Nordhaus' DICE model says, but that's because I've been studying his model thoroughly. In contrast, I hadn't examined the Second Working Group report of the AR4; I had focused mainly on WGI's discussion of the physical science of climate change.
But look what I just stumbled upon, from the overall Synthesis of the AR4. This comes from the 3rd last paragraph in the entire summary [.pdf]. Is this saying what I think it's saying? Seriously, those of you who are big fans of the IPCC--or at least, who think that the "deniers" and "skeptics" are making mountains out of molehills--please explain the following paragraph.
Limited and early analytical results from integrated analyses of the costs and benefits of mitigation indicate that they are broadly comparable in magnitude, but do not as yet permit an unambiguous determination of an emissions pathway or stabilisation level where benefits exceed costs.
I think we can all see now why Joe Romm et al. are taking such pains to ridicule the very notion of applying a cost/benefit test to climate policies.
UPDATE: OK I think that the IPCC statement really is poorly worded. I just waded through Chapter 3 of the AR4 Working Group III book, and I didn't see anything about comparing abatement costs with the benefits of avoided climate damage. (Nordhaus does this very clearly in his book discussion [.pdf] of the latest DICE model results.) What I did see was a discussion showing that the range of estimated prices for carbon emissions (under various policies like cap and trade) roughly overlapped with the estimated values of the "social cost" of carbon emissions.
I'll post more on this stuff later in the week, but for now let me just say that this isn't at all what the quotation above is saying. In the absence of enforcement costs and other frictions, the optimal policy would set the price of emitting a ton of carbon equal to its social cost. But even though this would equate the (marginal private) cost with the (marginal social) benefit, it's not true to say the "costs and benefits" of this policy are the same. On the contrary, there would be large net benefits because emitters would scale back their output of GHGs to the socially optimal point.
Rereading the IPCC quotation, I am still not sure what's going on. Surely they wouldn't have let some non-economist write the summary, right? And yet, they are clearly saying that the policies don't yield net benefits. Hmmmm.
Comments:
Howdy bob.
The "Greenhouse effect" is actually a misnomer. The effect that the atmosphere supposedly has does not work like a greenhouse because the primary method in which a greenhouse retains heat is not through the "accumulation of long-wave radiation" produced by re-emitted heat from the surface when solar radiation actually heats it. It is actually from preventing natural convection currents from allowing hot air to rise into the atmosphere and be raplaced by colder air on the surface.
There is actually a very good paper written by a well-informed theoretical physicist which not only takes to task much of the data on atmospheric global warming, but even goes so far as asserting that the underlying physics say it is impossible for it to occur, regardless of what concentration of water vapor or CO2 is in the atmosphere.
here is the link.
http://arxiv.org/PS_cache/arxiv/pdf/0707/0707.1161v4.pdf
The "Greenhouse effect" is actually a misnomer. The effect that the atmosphere supposedly has does not work like a greenhouse because the primary method in which a greenhouse retains heat is not through the "accumulation of long-wave radiation" produced by re-emitted heat from the surface when solar radiation actually heats it. It is actually from preventing natural convection currents from allowing hot air to rise into the atmosphere and be raplaced by colder air on the surface.
There is actually a very good paper written by a well-informed theoretical physicist which not only takes to task much of the data on atmospheric global warming, but even goes so far as asserting that the underlying physics say it is impossible for it to occur, regardless of what concentration of water vapor or CO2 is in the atmosphere.
here is the link.
http://arxiv.org/PS_cache/arxiv/pdf/0707/0707.1161v4.pdf
# posted by 
: May 23, 2009 at 1:17 AM
: May 23, 2009 at 1:17 AM
"Even the really scary projections of huge damages from business-as-usual don't kick in until after 2100."
I guess you`re only referring to the IPPC, and missed the latest MIT study?
The new projections, published this month in the American Meteorological Society's Journal of Climate, indicate a median probability of surface warming of 5.2 degrees Celsius [9 degrees F!] by 2100, with a 90% probability range of 3.5 to 7.4 degrees [6.3 to 13.2 degrees F!]. This can be compared to a median projected increase in the 2003 study of just 2.4 degrees [and the temps reported are averages, with many places warmer].http://mises.org/Community/blogs/tokyotom/archive/2009/05/22/new-mit-study-climate-warming-odds-much-worse-than-thought-quot-increases-the-urgency-for-significant-policy-action-quot-quot.aspx
"half of the entire earth's productive capacity is destroyed because of our destructive emissions"
I fail to see the IPCC`s explanation of the cost of carbon pricing as a "trick". The only real trick involved here is your failure, while playing with GDP numbers, to price the value of the net transfer to fossil fuel producers and users from a BAU policy that leaves the use of the atmosphere as a free for all.
And certainly the IPCC doesn`t say we must "immediately hand over the energy sector to the federal government." We have a wide range of policy options. Republicans under Bush chose on climate, as on so many other policies, to continue those that generate moral hazard.
You also ignore that this is a multi-nation game, featuring Coasean bargaining by nations that more or less imperfectly represent the preferences of their citizens (mainly the most powerful ones).
You also ignore the tremendous inertia and uncertainty in the climate system. If we want to change course, it`s worth starting early, even with a gentle nudge (as Nordhaus and others have been arguing for decades)
"in order to make immediate action seem necessary for any cost/benefit test that isn't completely rigged."
Given the disparate impacts, some economic resources are expected to be destroyed, but literally the IPCC is referring to reduced growth.
But you ignore that the involuntary transfer of wealth inherent on the whole process, and that Locken principles give us no right to harm others (and that every individual adversely affected by climate change has a right to enjoin our activities that cause harm).
but do not as yet permit an unambiguous determination of an emissions pathway or stabilisation level where benefits exceed costs.Can I offer an opinion even if I am not a "big fan of the IPCC" or don`t think that the "deniers" and "skeptics" are making mountains out of molehills"?
I guess you`re only referring to the IPPC, and missed the latest MIT study?
The new projections, published this month in the American Meteorological Society's Journal of Climate, indicate a median probability of surface warming of 5.2 degrees Celsius [9 degrees F!] by 2100, with a 90% probability range of 3.5 to 7.4 degrees [6.3 to 13.2 degrees F!]. This can be compared to a median projected increase in the 2003 study of just 2.4 degrees [and the temps reported are averages, with many places warmer].http://mises.org/Community/blogs/tokyotom/archive/2009/05/22/new-mit-study-climate-warming-odds-much-worse-than-thought-quot-increases-the-urgency-for-significant-policy-action-quot-quot.aspx
"half of the entire earth's productive capacity is destroyed because of our destructive emissions"
I fail to see the IPCC`s explanation of the cost of carbon pricing as a "trick". The only real trick involved here is your failure, while playing with GDP numbers, to price the value of the net transfer to fossil fuel producers and users from a BAU policy that leaves the use of the atmosphere as a free for all.
And certainly the IPCC doesn`t say we must "immediately hand over the energy sector to the federal government." We have a wide range of policy options. Republicans under Bush chose on climate, as on so many other policies, to continue those that generate moral hazard.
You also ignore that this is a multi-nation game, featuring Coasean bargaining by nations that more or less imperfectly represent the preferences of their citizens (mainly the most powerful ones).
You also ignore the tremendous inertia and uncertainty in the climate system. If we want to change course, it`s worth starting early, even with a gentle nudge (as Nordhaus and others have been arguing for decades)
"in order to make immediate action seem necessary for any cost/benefit test that isn't completely rigged."
Given the disparate impacts, some economic resources are expected to be destroyed, but literally the IPCC is referring to reduced growth.
But you ignore that the involuntary transfer of wealth inherent on the whole process, and that Locken principles give us no right to harm others (and that every individual adversely affected by climate change has a right to enjoin our activities that cause harm).
but do not as yet permit an unambiguous determination of an emissions pathway or stabilisation level where benefits exceed costs.Can I offer an opinion even if I am not a "big fan of the IPCC" or don`t think that the "deniers" and "skeptics" are making mountains out of molehills"?
As usual Tom, you list all of the things I neglected to say in my post. But are you agreeing with me, that the IPCC--which is the "consensus" used to beat back the deniers when it comes to the physical issues--is admitting here that its models can't yet clearly demonstrate that carbon mitigation policies will have a net benefit?
Isn't that a bit odd, to say the least?
Isn't that a bit odd, to say the least?
Good question and analysis. Let's assume that human-driven, GHG-induced CC is happening. Let's also agree that there are damages in the future (50% drop in GDP). Without commenting on $326k vs. $640k in absolute terms, I'll say that action IS justified b/c the "standard of living" (what? no rocket cars?!?) will be lower.
Besides that, I agree that C/B is dangerous here. I'll also agree that the uncertainty (esp. range of scenarios) is problematic. At that point, I am happy to go with the median estimate instead of worrying about CIs.
But NONE of this matters IF there's going to be CC legislation. Time to move to a different topic, i.e., how to introduce the least-harmful policy. You need to put your brains into lobbying for a carbon tax as our worst nightmares on C&T are now appearing in DC...
Besides that, I agree that C/B is dangerous here. I'll also agree that the uncertainty (esp. range of scenarios) is problematic. At that point, I am happy to go with the median estimate instead of worrying about CIs.
But NONE of this matters IF there's going to be CC legislation. Time to move to a different topic, i.e., how to introduce the least-harmful policy. You need to put your brains into lobbying for a carbon tax as our worst nightmares on C&T are now appearing in DC...
"As usual Tom, you list all of the things I neglected to say in my post."Somebody has to, I suppose. Are they irrelevant or unimportant points?
I won`t repay the comment by stating that, as usual, you neglect to respond to the things I point out, since that would hardly encourage you to do so, and would be an overstate as well.
I would have volunteered more, but was disinclined to respond to a question directed to "big fans of the IPCC" and those who don`t "think that the "deniers" and "skeptics" are making mountains out of molehills".
"is [the IPCC] admitting here that its models can't yet clearly demonstrate that carbon mitigation policies will have a net benefit?"Thanks for asking.
When they [the governments that signed off on the report] say, "Limited and early analytical results from integrated analyses of the costs and benefits of mitigation indicate that they are broadly comparable in magnitude, but do not as yet permit an unambiguous determination of an emissions pathway or stabilisation level where benefits exceed costs", they mean:
- in their view, the costs and benefits of mitigation [an enormous sweep of possible policies across the world, on a aggregate basis] are roughly comparable, and
- they acknowledge that they can`t offer clear guidance on what global mitigation path or stabilization level is justified on a cost-benefit basis. Implicit is the recognition that some mitigation targets might NOT be justifiable on a CBA basis.
What`s surprising about this? Austrians have fundamental problems the whole CBA endeavor, and even it`s most ardent fans recognize the difficulty in applying it to the Earth`s climate and to the choices of hundreds of governments and billions of individuals.
And besides, has the IPCC been tasked by anyone to suggest mitigation paths, stabilization levels or the policies that would be needed to achieve them?
I won`t repay the comment by stating that, as usual, you neglect to respond to the things I point out, since that would hardly encourage you to do so, and would be an overstate as well.
I would have volunteered more, but was disinclined to respond to a question directed to "big fans of the IPCC" and those who don`t "think that the "deniers" and "skeptics" are making mountains out of molehills".
"is [the IPCC] admitting here that its models can't yet clearly demonstrate that carbon mitigation policies will have a net benefit?"Thanks for asking.
When they [the governments that signed off on the report] say, "Limited and early analytical results from integrated analyses of the costs and benefits of mitigation indicate that they are broadly comparable in magnitude, but do not as yet permit an unambiguous determination of an emissions pathway or stabilisation level where benefits exceed costs", they mean:
- in their view, the costs and benefits of mitigation [an enormous sweep of possible policies across the world, on a aggregate basis] are roughly comparable, and
- they acknowledge that they can`t offer clear guidance on what global mitigation path or stabilization level is justified on a cost-benefit basis. Implicit is the recognition that some mitigation targets might NOT be justifiable on a CBA basis.
What`s surprising about this? Austrians have fundamental problems the whole CBA endeavor, and even it`s most ardent fans recognize the difficulty in applying it to the Earth`s climate and to the choices of hundreds of governments and billions of individuals.
And besides, has the IPCC been tasked by anyone to suggest mitigation paths, stabilization levels or the policies that would be needed to achieve them?
David, thanks for the comments. (And your picture is a lot nicer than Tokyo Tom's.) I understand where you're coming from, but I disagree with your strategy. After all, I think it's safe to say that if any carbon legislation is coming out of DC, it's going to be cap & trade. So Joe Romm or Paul Krugman could just as easily say to you, "Use your brains to help us lobby for 100% auctions." See what I mean?
If I were a senator or something, that type of thinking might make sense. But since I am probably not going to be the difference on the margin, I will stick to a "purer" defense of what I think the real answer is. Of course, having said that, a lot of what I've written on this topic lately shows how much worse cap & trade is than a carbon tax, so I'm trying to have it both ways you could say.
Tokyo Tom, you raise some good points. But again, don't you see that you are often not disagreeing with a single thing I say in a post or article or speech, but instead you are criticizing me for what I leave out?
And so if that's the case, I don't know why your tone is always so judgmental (unless I'm misreading you). It's not, "Hey good job, I agree 100%, but next time why not mention...X?" Rather it's, "Sure sure, I suppose that's all true, but if you weren't in it for the money and fame you'd say X."
If I were a senator or something, that type of thinking might make sense. But since I am probably not going to be the difference on the margin, I will stick to a "purer" defense of what I think the real answer is. Of course, having said that, a lot of what I've written on this topic lately shows how much worse cap & trade is than a carbon tax, so I'm trying to have it both ways you could say.
Tokyo Tom, you raise some good points. But again, don't you see that you are often not disagreeing with a single thing I say in a post or article or speech, but instead you are criticizing me for what I leave out?
And so if that's the case, I don't know why your tone is always so judgmental (unless I'm misreading you). It's not, "Hey good job, I agree 100%, but next time why not mention...X?" Rather it's, "Sure sure, I suppose that's all true, but if you weren't in it for the money and fame you'd say X."
General comment: I am astounded that no one else thinks this is a significant admission by the IPCC. TT, they are indeed "tasked" with these things as much as with the physical science. Working Group I was the physical science, Working Group II was quantifying the impacts of AGW, and Working Group III was quantifying the costs of mitigation.
They used the same type of approach in all three Working Groups--coming up with statements that they could defend with various degrees of confidence, after having surveyed the peer reviewed literature.
So, if many many many people (not necessarily you are David Zetland) fall back on the IPCC as the Bible whenever some "denier" on a blog comment brings up Lindzen, then why can't I do the same whenever someone like Joe Romm or Paul Krugman says fighting climate change makes tons of sense? After all, the IPCC surveyed all of that literature and couldn't find a compelling case that the benefits of fighting AGW exceed the costs.
I am still shocked that they said that. I am waiting for a pro-carbon-tax person to explain that I'm misreading the quote. I was not expecting everyone to shrug it off.
They used the same type of approach in all three Working Groups--coming up with statements that they could defend with various degrees of confidence, after having surveyed the peer reviewed literature.
So, if many many many people (not necessarily you are David Zetland) fall back on the IPCC as the Bible whenever some "denier" on a blog comment brings up Lindzen, then why can't I do the same whenever someone like Joe Romm or Paul Krugman says fighting climate change makes tons of sense? After all, the IPCC surveyed all of that literature and couldn't find a compelling case that the benefits of fighting AGW exceed the costs.
I am still shocked that they said that. I am waiting for a pro-carbon-tax person to explain that I'm misreading the quote. I was not expecting everyone to shrug it off.
Bob, again, the IPCC was simply not tasked to project its own "best" climate targets and policies on the basis of CBA, or to apply CBA to any particular targets, to be achieved within particular timeframes by the world community.
In any event the whole business of evaluating the future is loaded with uncertainties and fundamental problems of weighing benefits in some places with costs in others and the differing preferences of a billions of people, all unequally situated.
How could you possibly expect anyone honestly to come up with an "unambiguous determination" is beyond me.
If you`re really interested in what the IPCC has done regarding CBA, I suggest you look at the WG3 report (if you haven`t already), particularly ch.3:
http://www.ipcc.ch/ipccreports/ar4-wg3.htm
"After all, the IPCC surveyed all of that literature and couldn't find a compelling case that the benefits of fighting AGW exceed the costs."
This is not at all what they set out to do, or what they said.
But there sure are plenty of economists out there using CBA who have been arguing for decades now that pricing carbon makes sense. Even your friend Jim Manzi thinks we ought to start spending money on it.
In any event the whole business of evaluating the future is loaded with uncertainties and fundamental problems of weighing benefits in some places with costs in others and the differing preferences of a billions of people, all unequally situated.
How could you possibly expect anyone honestly to come up with an "unambiguous determination" is beyond me.
If you`re really interested in what the IPCC has done regarding CBA, I suggest you look at the WG3 report (if you haven`t already), particularly ch.3:
http://www.ipcc.ch/ipccreports/ar4-wg3.htm
"After all, the IPCC surveyed all of that literature and couldn't find a compelling case that the benefits of fighting AGW exceed the costs."
This is not at all what they set out to do, or what they said.
But there sure are plenty of economists out there using CBA who have been arguing for decades now that pricing carbon makes sense. Even your friend Jim Manzi thinks we ought to start spending money on it.
Both of your points are quite serious. Playing with the yearly percentages will work, of course, since most people don't know arithmetic. As to the overall cost-benefit skepticism of the report, I am very surprised. But this is another example of the difficulties of cost benefit analysis. I wrote about these in a a paper (unpublished) on the application of cost-benefit analysis to a nuclear power case. I'll find it and scan it for wider readership. The gist is that when costs or benefits are vague, either because of uncertainty or other measurement difficulties, the whole enterprise reaches its limit.
TT wrote:
Bob, again, the IPCC was simply not tasked to project its own "best" climate targets and policies on the basis of CBA, or to apply CBA to any particular targets, to be achieved within particular timeframes by the world community.
I didn't say that it was. It was tasked to review the state-of-the-art literature so policymakers would know what the heck they were doing. So WGI told policymakers what the "best guess" of the natural scientists were, regarding GHG emissions and climate change. WGII told policymakers what the "best guess" of the environmental economists and other experts was, regarding the impacts of this climate change on humans. And WGIII told policymakers what the "best guess" of the leading models was, concerning the net benefits of various mitigation strategies. And that quote sure sounds like they were saying, "We hate to judge on something like this before all the facts are in, but as of right now there is no obvious policy that yields clear net benefits from fighting climate change. Sure we could reduce the climate damages, but at the cost of forfeited economic growth that roughly offsets the climate savings."
How could you possibly expect anyone honestly to come up with an "unambiguous determination" is beyond me.
Are you serious? The issue isn't the optimal path for fighting climate change. They are saying they cannot point to one single path that unambiguously has net benefits.
They have no problem coming up with an "unambiguous determination" that human emissions are contributing to global warming. Yet by their own admission, they can't show that any particular set of policies will counteract that inconvenient truth.
[Bob Murphy said:] "After all, the IPCC surveyed all of that literature and couldn't find a compelling case that the benefits of fighting AGW exceed the costs."
This is not at all what they set out to do, or what they said.
OK now we're getting somewhere! Please parse their quotation from my original blog post, and tell me why I am misreading it. Like I said, that's where I expected this debate to come down on, that I was misreading their quote. So tell me why I'm wrong in my interpretation of it. It sure sounds to me as if they're saying, "We can't point to a set of policies to fight climate change that yields obvious net benefits."
But there sure are plenty of economists out there using CBA who have been arguing for decades now that pricing carbon makes sense.
I know! That's why I was so stunned when I saw this IPCC quote.
Bob, again, the IPCC was simply not tasked to project its own "best" climate targets and policies on the basis of CBA, or to apply CBA to any particular targets, to be achieved within particular timeframes by the world community.
I didn't say that it was. It was tasked to review the state-of-the-art literature so policymakers would know what the heck they were doing. So WGI told policymakers what the "best guess" of the natural scientists were, regarding GHG emissions and climate change. WGII told policymakers what the "best guess" of the environmental economists and other experts was, regarding the impacts of this climate change on humans. And WGIII told policymakers what the "best guess" of the leading models was, concerning the net benefits of various mitigation strategies. And that quote sure sounds like they were saying, "We hate to judge on something like this before all the facts are in, but as of right now there is no obvious policy that yields clear net benefits from fighting climate change. Sure we could reduce the climate damages, but at the cost of forfeited economic growth that roughly offsets the climate savings."
How could you possibly expect anyone honestly to come up with an "unambiguous determination" is beyond me.
Are you serious? The issue isn't the optimal path for fighting climate change. They are saying they cannot point to one single path that unambiguously has net benefits.
They have no problem coming up with an "unambiguous determination" that human emissions are contributing to global warming. Yet by their own admission, they can't show that any particular set of policies will counteract that inconvenient truth.
[Bob Murphy said:] "After all, the IPCC surveyed all of that literature and couldn't find a compelling case that the benefits of fighting AGW exceed the costs."
This is not at all what they set out to do, or what they said.
OK now we're getting somewhere! Please parse their quotation from my original blog post, and tell me why I am misreading it. Like I said, that's where I expected this debate to come down on, that I was misreading their quote. So tell me why I'm wrong in my interpretation of it. It sure sounds to me as if they're saying, "We can't point to a set of policies to fight climate change that yields obvious net benefits."
But there sure are plenty of economists out there using CBA who have been arguing for decades now that pricing carbon makes sense.
I know! That's why I was so stunned when I saw this IPCC quote.
Mario,
I would love to see your analysis of the limits of CBA.
And to make it clear, of course I am very skeptical of CBA (as practiced in these contexts) as well. E.g. there is a whole cottage industry where economists come in and sign off on local government development projects that have a positive CBA. Duh.
But my point with all of this is, we have been beat over the head with "consensus consensus consensus" when it comes to the WGI report. Anybody who points to a Lindzen model is told, "He is an outlier. The IPCC has summarized the peer-reviewed literature, and the expert community agrees that humans are causing global warming."
So it just strikes me as incredible that the same IPCC report concedes that they cannot find unambiguous model results in which fighting climate change has net benefits.
I am still stunned by that.
I would love to see your analysis of the limits of CBA.
And to make it clear, of course I am very skeptical of CBA (as practiced in these contexts) as well. E.g. there is a whole cottage industry where economists come in and sign off on local government development projects that have a positive CBA. Duh.
But my point with all of this is, we have been beat over the head with "consensus consensus consensus" when it comes to the WGI report. Anybody who points to a Lindzen model is told, "He is an outlier. The IPCC has summarized the peer-reviewed literature, and the expert community agrees that humans are causing global warming."
So it just strikes me as incredible that the same IPCC report concedes that they cannot find unambiguous model results in which fighting climate change has net benefits.
I am still stunned by that.
Actually I misspoke: Lindzen doesn't have a "skeptic model" because his whole point is that the standard models (necessarily because of computational constraints) leave out important stuff.
So by the same token, go ahead and rip CBA; that's fine. But notice the asymmetry. The arguments the interventionists use to throw out Lindzen and Spencer, I can use to throw out Nordhaus and others who find net benefits of pricing carbon in their models.
Unless, that is, I am misreading the IPCC quotation.
So by the same token, go ahead and rip CBA; that's fine. But notice the asymmetry. The arguments the interventionists use to throw out Lindzen and Spencer, I can use to throw out Nordhaus and others who find net benefits of pricing carbon in their models.
Unless, that is, I am misreading the IPCC quotation.
"Please parse their quotation from my original blog post, and tell me why I am misreading it."
"Unless, that is, I am misreading the IPCC quotation."
"OK I think that the IPCC statement really is poorly worded."
Glad I could be of help, Bob, in my usual unhelpful way.
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"Unless, that is, I am misreading the IPCC quotation."
"OK I think that the IPCC statement really is poorly worded."
Glad I could be of help, Bob, in my usual unhelpful way.
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