TOL AND FANKHAUSER
Meyer and Cooper have written an interesting article, which points out many important issues in the economic assessment of the impact of climate change. On several fronts we agree with the authors, and the criticised IPCC chapter often makes the same points as Meyer and Cooper (e.g. on the importance of uncertainty and extreme events, and the limitations of the 2xCO2 benchmark). In some other aspects, however, we fundamentally disagree. We would like to thank the editor of The Ecologist for giving us the opportunity to react, make clarifications on the IPCC Social Cost chapter, and point the reader to a number of misconceptions in the paper by Meyer and Cooper.
GCI COMMENTS BACK
Whilst GCI has focused on the need for attention to "uncertainty", and focused attention on the "limitations of 2xCO2 as a benchmark", we have not focused on the need for attention to "extreme events" (that is extreme climatic events or catastrophe scenarios) in our numerical reassessment. Fankhauser and Tol are incorrect in suggesting that we have. The expectation of extreme events is one reason why even our substantially increased damage estimates should be treated as conservative.
TOL AND FANKHAUSER CONTINUED
IPCC
The IPCC was established by the World Meteorological Organisation and the United Nations Environment Programme to provide sound scientific analysis that can assist policy makers in deciding on the appropriate course in climate policy. The IPCC is a scientific panel, which critically assesses the relevant literature. The IPCC does not carry out its own research, take position, or give advice. The IPCC merely reflects the literature, and presents it in a comprehensive and accessible way.
GCI COMMENTS BACK In Pearce's latest book Blueprint 4, he acknowledges his own extensive references to Fankhauser's material (in his book "Valuing Climate Change") which he describes as "work done for the IPCC".
Fankhauser in his book "Valuing Climate Change" says "Global warming research is strongly in the hands of the IPCC". Cline, Tol, Fankhauser and Pearce are all IPCC Social Cost authors, and - as such - all are assessing predominantly their own work conducted outside the IPCC Second Assessment Report (SAR) , but apparently for the SAR itself.
To say in these circumstances, "the IPCC does not carry out its own research, take position, or give advice. The IPCC merely reflects the literature, and presents it in a comprehensive and accessible way," is misleading.
TOL AND FANKHAUSER CONTINUED
IPCC reports are written by teams of internationally leading experts, carefully balanced between the geopolitical regions.
GCI COMMENTS BACK The authorship line-up for the SAR is still over-whelmingly OECD- based experts. The chapter has 233 references which - with the exception of two or three - are by authors based in institutions in the Industrial Countries.
TOL AND FANKHAUSER CONTINUED The reports go through an extensive peer and government review.
GCI COMMENTS BACK This review process is not infallible as Dr Tol has admitted elsewhere. There is the undetected error to do with the derivation of regional damages expressed as percents of GDP.
Before the Geneva meeting GCI asked that the error be acknowledged and corrected. These authors refused to do this. After the Geneva meeting in a posting to ecol-econ (the internet conference where much of this has been debated), Dr Tol made the following admission. "The PPP correction reflects a slip in the literature which amazingly survived many reviews, including the IPCC's." However he went on to say, "IPCC cannot correct the literature, but in the present wording the slip is clear for all to see."
TOL AND FANKHAUSER CONTINUED Non-governmental organisations are also admitted to the review procedure, and many have taken up this opportunity. Meyer and Cooper mainly comment on Chapter 6 of the Second Assessment Report of Working Group III: 'The Social Costs of Climate Change'.
The chapter was written in 1994 by a team of seven researchers, headed by Prof. David Pearce of University College London. The team members are from Europe, India and the United States, and have backgrounds in economics, biology, statistics, civil engineering and anthropology. The chapter went through the IPCC review process in 1995 and was revised in the light of many helpful comments.
GCI COMMENTS BACK Two of the seven team members are from C-SERGE in the UK, two are from the Free University Amsterdam, one is from the United States and the remaining two are from TERI (Tata Energy Research Institute) which is based in both Delhi and Washington DC. This is typical of the IPCC as a whole and reflects available funding, and cannot reasonably be described as carefully balanced between the geopolitical regions. As it stands, the chapter betrays fails to reflect the literature on economic anthropology, or indeed any of the insights of anthropology into social organisation and the politics of decision making.
TOL AND FANKHAUSER CONTINUED The chapter is now finalised and awaits official adoption by the governments of the United Nations.
GCI COMMENTS BACK If the IPCC is other than a rubber stamp, the report does not merely await adoption. There is no good reason why IPCC should publish known wrong data. There is every good reason why the IPCC should insist on revisions prior to publication.
TOL AND FANKHAUSER CONTINUED
Comparison of Estimates
Meyer and Cooper list a series of issues - willingness to pay versus willingness to accept, regional differentiation, aggregation, cost benefit analysis, timing, market exchange rates versus purchasing power parity, uncertainty and omitted damage categories - and we address the major ones. Lumping everything together, Meyer and Cooper derive damage estimates of 12-130% of Gross World Product (GWP) for 2xCO2, compared to the 1.5-2% best guess of IPCC Chapter 6.But the two sets of estimates are based on different assumptions, and are therefore not comparable.
GCI COMMENTS BACK One of the main points of our paper is to highlight the extreme sensitivity of damage estimates on the set assumptions used. It is simply not true to say that our different assumptions render the conclusions incomparable. At this point - especially having had the open contention about unequally valued lives - we should recognise that this debate is all about different assumptions and the different results you get from different assumptions.
TOL AND FANKHAUSER CONTINUED The studies underlying Chapter 6 estimate the impact of a climate change induced by 2xCO2 on the present economy. In line with IPCC Working Group 1 we assumed 2.5 C warming. Since the analysis is static, issues such as the timing of 2xCO2, feedback effects, and aerosols, which Meyer and Cooper cover in some depth, are irrelevant for 2xCO2 damage estimation. Currently, research is being undertaken on the impact of other- than-2xCO2-climate-change on other-than-the- present-economy. The results are too premature to be taken up in the IPCC, given the explicit requirements laid down by IPCC to authors.
GCI COMMENTS BACK To suggest that aerosols and feedbacks are irrelevant to the analysis - static or not - is a quite unjustified statement. One of our main points is that it is precisely the static nature of the 2xCO2 evaluations which is misleading. The IPCC certainly did NOT prescribe that the damages had to be assessed for 2xCO2 only. This is a limitation the economists imposed on themselves presumably because it suits their preferred methodology.
WG3 itself has been in the business of assessing emissions "scenarios" which are certainly not static and would have provided a useful basis for assessment of rolling and accumulating damage costs. The authors were apparently not favourably disposed to these non-CBA oriented techniques of assessment.
TOL AND FANKHAUSER CONTINUED Meyer and Cooper analyse different scenarios with warming mostly greater than 2.5 C. Calculating different scenarios is useful. However, for a reasonable comparison we have to compare like with like. Their estimate closest to the 2.5 C warming scenario of IPCC would probably be in the order of 30% of GWP (given that the move from their scenario B to C increases medium damage by 175%). The discrepancy is thus much smaller, although theirs is still a much larger figure. The difference is mainly due to two reasons. The first is the inclusion of malnutrition and malaria damages. This is a useful extension, although the Hohmeyer and Gaertner estimates adopted by Meyer and Cooper appear to be huge overestimates in the light of the much more sophisticated work by Rosenzweig and Parry (on malnutrition) and Martens et al. (on malaria).
GCI COMMENTS BACK These areas are even more uncertain than most. Our reading of the recent reports on malarial research suggests that very large land areas will become newly malarious, though we have not seen a quantification of the numbers of cases expected. Malnutrition is less amenable to scientific research: we have no independent verification of Hohmeyer and Gaertner's estimates, but it is hardly credible that a doubling of present levels should be regarded as inconceivable. And the main point is that a justified estimate of these factors must be included in any costing which is expected to be taken seriously.
TOL AND FANKHAUSER CONTINUED The second reason is the uniform valuation approach taken by Meyer and Cooper. This is the issue where we most fundamentally disagree with the authors.
GCI COMMENTS BACK Uniform valuation is an ethical absolute, as least for lives, statistical or otherwise, and other 'intangible' factors - i.e. those where the direct impact is on people and the indirect impact on the economy, rather than vice versa.
TOL AND FANKHAUSER CONTINUED Uniform Unit Values - Meyer and Cooper frame the issue of uniform valuation in the context of the debate on willingness to pay (WTP) and willingness to accept compensation (WTAC). This is wrong. The choice between WTP and WTAC has no relationship with the question of regionally diversified value estimates, contrary to the suggestion of Meyer and Cooper.
GCI COMMENTS BACK Just because Tol and Fankhauser says this is wrong doesn't make it wrong. Kenneth Arrow - another IPCC lead author and Nobel laureate for Economics - says that WTAC is the "conceptually correct" question and that WTP is the "conceptually incorrect" question. We didn't have time however to go round and ask all the victims of climate change what they would be willing to accept as compensation. [This alone justifies PUDV as a sort of compromise approach (see GCI paper)]. WTP embodies the ethics of the protection racketeer. It has no place in a civilised debate. Its use is clearly part of the same conceptual framework which leads to differential value rates.
TOL AND FANKHAUSER CONTINUED WTAC, like WTP, depends on income (even though bids are not constrained by income). A rich person will require a higher monetary compensation than a poor person, because his marginal utility of income is lower (a compensation of, say, $1,000 compensation is less interesting to a rich person than to a poor person). WTAC estimates might lead to higher damages, but they would still differ between regions. WTAC can therefore not be used to justify uniform values at the OECD level. But the concept of uniform values at OECD levels for all (market and non-market) damages is itself flawed. Meyer and Cooper fail to give a good reason for using it other than quoting other authors who have themselves failed to give a good reason.
GCI COMMENTS BACK
We give a number of reasons for adopting OECD values, mostly not based on other authors, though undoubtedly supported by Hohmeyer and Ekins, at least. To say ours (and theirs) are not 'good' is an unsubstantiated value judgement.
Use of global average values is seductive and we considered doing it to enhance our other points. But in fact it merely masks the underlying inequity. For what is being averaged if not a high OECD value and a low RoW value?
To say that WTAC, like WTP, depends on income is a misleading half- truth. In "normal" circumstances - where for example mass mortality is not on the agenda - a rich person may require a higher monetary compensation than a poor person, because his marginal utility of income is lower. But we are not talking about compensating rich people here. We are talking about compensating innocent people whose lives are going to be lost as a result of unrestrained damages caused by polluters.
Moreover, to say that WTAC estimates might lead to higher damages, but they would still differ between regions is a pure supposition. Furthermore we are not using WTAC to justify uniform values at the OECD level. We are using - inter alia - the conflict between the obviously different results from WTP and WTA as the justification.
To say that the concept of uniform values at OECD levels for all (market and non-market) damages is itself flawed, is also wrong. Ultimately, the inter-dependent global resources at risk belong to all of us equally or not at all. People who are being told that they have a lesser or non-existent or even negative stake in these, have no or even negative incentive for conservation of these resources. Surely the economists do not want to promote the advent of such a disposition
TOL AND FANKHAUSER CONTINUED The whole purpose of regional damage analysis is to capture the regional diversity and assess differences in vulnerability. Regions differ in many respects, not the least in price and income levels.
GCI COMMENTS BACK Firstly these two authors fail to take up the point that income convergence is on the cards by the time of their assumed 2xCO2 (2050/60). So differential Ability-To-Pay (ATP) will have decreased by then. (ref. Nordhaus). Moreover, differing degrees of vulnerability is not an argument for differing valuation methods. To say it is, is tantamount to saying that because Bangladesh is much more vulnerable than the UK, Bangladeshi human and non-human resources must be valued differently on a unit damage basis.
TOL AND FANKHAUSER CONTINUED Using uniform unit damages defies this. It makes very little sense to estimate the costs of building a sea wall in India at US prices. Even if the US would fund the project, it would still be built in India using local workers and material paid at local rates. The same argument holds for intangible goods and services. Environmental commodities may serve different functions in different regions. To assess local vulnerability, it is the regional value that counts.
GCI COMMENTS BACK This still naively assumes that innocent victims of damage caused by others, must nonetheless be obliged to pay for the damage caused by others. They may end up having to do this (eg Bhopal) but if this is the new ethic of development it is unlikely to be sustainable. International agreement on abatement seems wholly improbable to us while the issue of liability is denied assisted by economic disinformation..
TOL AND FANKHAUSER CONTINUED
The Value of Statistical Lives
The concept of uniform values was conceived in the context of the value of a statistical life (VOSL). In this context, it is sometimes argued that for equity reasons all statistical lives should be valued equally. This may be appealing at first sight, but the case is far less obvious once the difference between VOSL and the 'value of life' as such is understood. Besides, it would point in the direction of using an average uniform value, not the OECD value. We have no problems with using a global average value to assess world damages. In fact, estimates of local environmental damages are commonly based on regionally averaged unit values. This is both convenient and in line with the approach usually taken by national governments. However, as we have pointed out there, using average values does not change the global results of IPCC Chapter 6.
GCI COMMENTS BACK There is no case whatsoever for differential life valuation. No-one values non-statistical lives. Ethics demands equal values. See above for irrelevance of global average values.
TOL AND FANKHAUSER CONTINUED
Aggregation
Equity considerations are important in climate change policy, and to the extent WTP/WTAC estimates reflect the unfairness in the income distribution, this has to be corrected for. However, the way to do this is not by tinkering with the value system, but by giving different weights to different regions in the aggregation process. Comparison and aggregation are difficult, and cannot be done in an unambiguous manner. Ethical choices are required. Chapter 6 shows how these can be depicted.
GCI COMMENTS BACK Making equity weighting choices on top of what the economists themselves have called arbitrary numbers, is tinkering. Investigating the different values systems is not just fundamental, it is now unavoidable and urgently necessary for sustainable outcomes.
TOL AND FANKHAUSER CONTINUED PPP-Correction - The matter of market versus purchasing power parity exchange rates was not corrected because this issue is rather more complicated, although less far-reaching than Meyer and Cooper suggest.
GCI COMMENTS BACK
The arguments since the Geneva WG3 meeting have unfolded like this:
-. NO CHANGE/NO APOLOGY The Summary for Policy-Makers (SPM) of the " Social Costs" Chapter was not accepted at the Geneva meeting. Prof Pearce has now gone on the record in an interview in the New Scientist as saying, "we won't be revising it, and we have no intention of apologising for our work. This is a question of scientific correctness versus political correctness. One solution is for the IPCC to remove the chapter from its report entirely"
His chapter contains scientifically incorrect results which he mistakenly assumes are under attack for reasons of political correctness. In fact the error has arisen out of asking (what IPCC lead author and Economics Nobel laureate Kenneth Arrow has called) "the conceptually incorrect question" - ie Willingness-To-Pay Willingness-To-Pay (WTP) and getting what the Indian Environment Minister called, "an absurd and discriminatory result" in a letter to all heads of delegations at Conference of the Parties (COP) Berlin.
We make no comment on the politics that may or may not underlie Prof Pearce reasons for insisting on retaining the method adopted and the mistakes to which it has given rise. But we would however, observe that he has professional reasons for this intransigent position. None of this is in the best interests of the IPCC and we feel the decision to revise should be taken out of his hands.
WHAT IS THE 'TECHNICAL' ERROR?
The chapter contains a very significant arithmetical error, well buried in its text and numbers and only slightly now alluded to in a footnote in the Summary for Policy-Makers (SPM).
By misusing the concept of Purchasing Power Parity, and certainly not explaining the implications, it falsely inflates the calculated percent of GDP losses in developing countries by a factor of about 5. It does so by a method equivalent to dividing average French incomes in Francs by UK incomes in pounds (without taking account of exchange rates) to work out how much richer French people are than Britons.
Just how big a difference the erroneous calculation makes is shown by the following example. Pearce's colleague, Dr Fankhauser, calculated that the damage likely to be done by global warming in China at 2xCO2 expressed in 1988 local purchasing power terms as $16,700,000,000 which he (and the chapter) said are equivalent to 4.7% GDP losses. China's GDP in 1988 was $356,359,136,845 at current international exchange rates but $2,431,222,372,000 in terms of domestic purchasing power. In other words, if both damage and GDP are both expressed in domestic purchasing power, (the correct procedure) the losses are only 0.7% of China's 1998 GDP. What Chapter 6 does is to express LDC damages in domestic purchasing power but divide by GDP in international purchasing power to obtain regional "%s GDP losses". At best this is plain wrong, or at worst conscious misinformation to obscure the improbable distributional results obtained from the WTP-based assessments undertaken. This error was repeated (by Pearce, Tol and Fankhauser) for all developing regions of the world where of course the international purchasing power of the local currencies is mostly very weak, with the consequent exaggeration of %s GDP losses. The range of 2-9 % losses for LDCs in the chapter (eg table 6.6 - also now just published by Pearce as "work carried out for the IPCC") and in the SPM come only from this work by these authors exclusively. One of the premier analysts in the field of comparative international prices, Alan Heston of Pennsylvania University, says this about this 'slip', "It is absolutely unacceptable to divide an exchange rate converted GDP into a component that has been converted at PPPs if the object is to express the quantitative ratio of the two magnitudes."
ERROR NOW ADMITTED - TOL Before the Geneva meeting GCI asked that the error be acknowledged and corrected. The authors refused to do this. After the Geneva meeting in a posting to ecol-econ (the internet conference where much of this has been debated), Dr Tol made the following admission. "The PPP correction reflects a slip in the literature which amazingly survived many reviews, including the IPCC's." However he went on to say, "IPCC cannot correct the literature, but in the present wording the slip is clear for all to see."
GCI asserts that: - 1. We are talking about a major error, not a slip, 2. It is not clear for all to see with or without the footnote, 3. The data in question is exclusively in the IPCC- assessed literature of the three authors Tol, Fankhauser and Pearce who are also lead authors for the IPCC: it is therefore completely within their power to correct, 4. It is not IPCC's role to knowingly reproduce wrong data of any kind, let alone that derived from incompetent calculations of numbers (derived in turn from already politically controversial damage assessment techniques (ie WTP-based as opposed to WTA-based)).
ERROR STILL DENIED - FANKHAUSER
However the IPCC economists are now split amongst themselves. Since Geneva Sam Fankhauser has still insisted there is no problem. He wrote to GCI as follows,
"I don't think the issue of what to divide absolute damage figures with is a question of 'right' or 'wrong'. One can divide the damage figures with anything one wants - population, GDP, corrected GDP, area, or number of spotted owls - as long as the value is not zero. The question is which of those divisions makes sense, and some clearly make more sense than others (eg damage per spotted owl)."
"As far as I am concerned division by GDP and PPP- corrected GDP can both make sense. They may shed light on the same figures from a different angle, but neither method, is I think, per se 'wrong' (neither is, for that matter, damage per capita, at least for the regional figures). I chose GDP because I thought this to be a measure people are likely to be familiar with and understand."
GCI feels this is an unintended admission of incompetence. If this last point for example is the justification that persuaded these three economists to accept the erroneous technique, we all need to know why they used the 'less familiar' PPP-correction for the damages in the first place. If they'd stuck to GDP throughout, the problem of dividing apples into oranges would have never arisen.
Paul Ekins (economist at Birkbeck College) comments on Fankhauser's reply as follows.
"Of course, Sam is right that you can divide anything you like by anything you like; this is a trivial observation. The question is what you then call the resulting ratio. If you divide PPP damage by non-PPP GDP, then you get 'PPP damages per unit of non-PPP GDP'. This does not seem to me to pass his test of a sensible ratio. What you do not get is a percentage damage, which is the ratio I would have thought one was looking for, and the one which is most often quoted."
TOL AND FANKHAUSER CONTINUED To us, there is no 'right' answer to the question of how absolute figures should best be expressed.
GCI COMMENTS BACK Why bother to do this assessment if it turns out that one result is as good or as bad as another?
TOL AND FANKHAUSER CONTINUED Damages include both market and non-market impacts, while GDP (corrected or not) is restricted to market transactions. No division by a GDP-related figure therefore produces the 'clean' percentage ratio Meyer and Cooper aspire to.
GCI COMMENTS BACK The entire edifice of "costing externalities" (that so-called "non-market" impact etc) - as dreamed up by the economists - depends on converting these so-called non-market impacts to market/GDP equivalence (via so- called "contingent valuation" etc). This is what the economists agenda of "commensurability", the "common numeraire" and GDP-equivalence has been all about.
The "restriction" now imposed on the GDP in the argument above by Tol and Fankhauser, is tantamount to them saying that the economists have been wasting their (and everyone else's ) time by costing externalities, because their agenda of "commensurability" and the "common numeraire" has been actually been impossible all along.
Aside from this, GDP can be expressed - and indeed IS expressed - at exchange rate values and at PPP values. Everyone - IMF, W/Bank, OECD and others - have resorted to the PPP measure, in circumstances of the "spatial comparisons" of GDPs (that is across countries). This has been for reasons of avoiding the "distortion" of a country's relative GDP ranking in terms of its domestic purchasing power (under-representation of soft currency countries - ie LDCs, and over-representation of hard- currency countries - ie DCs) This is a reasonable way of attempting to reflect how important the purchasing power of a country's currency is to itself internally.
International "damage accountancy" - as conducted within the IPCC WG3 - recognised (correctly) that it would be unsuitable to express damages in a country with a poor exchange rate with the dollar, in exchange-rate based dollar equivalence. This is true because it would depreciate the internationally relative value of the damages in that country. Consequently damages in developing countries were (apparently) corrected by a PPP formula which corrected for disparities in purchasing power.
To go from there and suggest that it is then also sensible to divide these PPP corrected damages by GDP figures not so corrected, is pure nonsense. The justification that "there is no right way of doing it because it is complicated" is not an argument, it is an admission of defeat -. not a little supported by their apparent intention to go and correct their figures anyway (see immediately below).
TOL AND FANKHAUSER CONTINUED Nevertheless, PPP corrected figures are in preparation to illustrate the significance of this point, and will be published shortly.
GCI COMMENTS BACK
Alan Heston comments again (10/10/95) on this debate paraphrased as follows: on PPP, GCI has made the case clearly. The replies by Fankhauser and Tol document prevaricate. They are in wrong in saying that GDP is restricted to market transactions . . . in fact there are correlations when the valuation of the education and government sectors is at cost, this is analagous to what is being done for environmental damage. So the matter is not so complicated as they would say. Note that they say there is "no right answer to the absolute figures" (I take this to mean that they are not defending their ratio anymore), so it sounds to me as though GCI has made the point here. Also, they do say they are going to use PPP GDPS in the last sentence. If they do, then it will clear some of the smoke to get to more important issues.
TOL AND FANKHAUSER CONTINUED Cost-Benefit Analysis Being a scientific panel, Working Group 3 of the IPCC does not advocate cost benefit analysis as the appropriate tool for decision making, either at the global or the regional level.
GCI COMMENTS BACK If this were true, why have no cumulative damages been estimated to 2xCO2. We suggest that the answer to this question is that the figures were being expressed as annual damage figures so that the marginal cost of the damage could be computed (in a ratio of dollars per tonne carbon) so that they were harmonised with the potential costs of abatement (in a ratio of dollars per tonne carbon) being worked up elsewhere. If anyone doubts that the damages and abatement costs were destined for comparison, here is the relevant quote from David Pearce's foreword to Sam Fankhauser's book on the costs of climate change.
" . . . . . . . Sam Fankhauser has produced the most careful analysis yet of the likely economic damages arising from global warming. he is careful to provide regional estimates of damage as well as global costs. The stake of developing countries ion global warming control thus turns out to be larger than they themselves might have supposed. That suggests that the Framework Convention on Climate Change agreed at Rio in 1992, will have to adopt tougher and more comprehensive for its next phase beyond the year 2000. . . . .
Sam Fankhauser shows that measurable damage costs of doubling CO2 concentrations are around one percent to two percent of gross world product. THIS BENCHMARK FIGURE HAS TO BE COMPARED TO THE COST OF REDUCING EMISSIONS. THESE MAY AMOUNT TO FROM ONE PERCENT TO THREE PERCENT FOR A FIFTY PERCENT CUT BY 2025 IF TOPDOWN COSTING MODELS ARE USED." (GCI STRESS)
TOL AND FANKHAUSER CONTINUED It does discuss its advantages and disadvantages compared to other tools, such as the precautionary principle.
GCI COMMENTS BACK Discuss - but no numbers (GDP equivalence etc) for alternatives to CBA!
TOL AND FANKHAUSER CONTINUED Monetary estimates of the impacts of climate change do facilitate, but do not imply cost-benefit analysis, and are equally useful in other approaches to decision making.
GCI COMMENTS BACK We weren't just talking about monetary estimates, but ANNUAL SNAPSHOTS of monetary estimates. See all the comments about preparing for CBA as above.
TOL AND FANKHAUSER CONTINUED It is certainly true that CBA will not replace 'argument, discussion, negotiation and compromise', as Meyer and Cooper say (nor does Chapter 6 or any part of Working Group III suggest any such view).
GCI COMMENTS BACK We agree..
TOL AND FANKHAUSER CONTINUED But it is equally true that argument, discussion or negotiation uninformed by data on the costs and benefits involved is unlikely to produce a good compromise.
GCI COMMENTS BACK What is true in our judgement is that any negotiation process informed by the present results of Chapter 6 on the Social Costs of Climate Change will in fact have been seriously MIS-informed. The results must be revised to reflect a range of damages and distribution of damages along the lines of the GCI paper.