Europe’s Long Term Climate Target: A Critical Evaluation

February 14th, 2006

Posted by: admin

Ed.- Richard Tol, a professor at Hamburg, Vrije and Carnegie Mellon Universities. has written an interesting paper forthcoming in the journal Energy Policy critiquing the scientific basis for Europe’s temperature target for responding to global warming. Frequent readers of this blog will be familiar with discussions of the FCCC and “dangerous anthropogenic interference.” Prof. Tol adds to the diversity of perspectives here at Prometheus and offers a challenging, rigorous critique. Richard was kind enough to summarize his recent paper for us, so please read on. RP

The European Union have set a goal for international climate policy: The world should not warm more than 2°C above pre-industrial temperatures. This is an ambitious target. As the warming response to the enhanced greenhouse effect is so uncertain, it may imply that the atmospheric concentration of carbon dioxide could not rise much above 400 ppm, only some 20 ppm above today. If recent trends continue, the 400 ppm level would be reached by 2020. A 400 ppm target may require zero carbon emissions, worldwide, by 2050.

One may of course dismiss the European target. Who are they to decide on a global target? Perhaps the target is just political posturing and wishful thinking, or maybe it is just the opening bid in international negotiations. Perhaps European policy makers have been led to believe that deep emission reduction is easy and cheap. However, the European Union is a major player in international climate policy, and its 2°C target deserves serious discussion.


Unfortunately, the European Union seems unprepared for such as discussion. The 2°C target can be traced back to a 1995 report of the German government’s Scientific Advisory Council on Global Environmental Change (WBGU). Estimates of the economic impacts of climate change are a crucial argument in the WBGU report. At that time, the best guess for economic damages due to a doubling of the atmospheric concentration of carbon dioxide was 1.5% of global income. The WBGU raised this to 5.0% without any supporting analysis. Since 1995, economic impact estimates have been revised downwards, but the WBGU has not changed its target.

The WBGU continues to play a substantial role in setting targets for European climate policy. The German government follows its advice. The advisors to the Dutch government just translate its findings. The European Commission leans heavily on its reports. In its latest, 2003, report, the WBGU sticks to the 2°C target. It did revise the justification, however. For this, the WBGU commissioned a report by Bill Hare, a climate campaigner on the payroll of Greenpeace International. The Hare paper is in typical Greenpeace style: Selective citation, quotations out of context, and a focus on alarming examples.

The UK government has not explicitly adopted the 2°C target, but it has been arguing vigorously for stringent emission abatement. The UK position largely rests on two model results, by Nigel Arnell for water and by Pim Martens for malaria. The models predict hundreds of millions of people at risk of malaria and water stress. Unfortunately, these models omit adaptation. Bed nets and perhaps a vaccine could reduce the burden of malaria. Improved irrigation efficiency and desalination can overcome water shortage. Other modellers have been able to include such adaptation, and show that the Arnell and Martens models dramatically overestimate the impacts of climate change

The UK government is obliged to do a cost-benefit analysis of every major project or policy. On climate change, it duly issued a well-crafted report on the social cost of carbon, that is, the target price for carbon permits. The report was well in line with the academic literature, but its summary recommended a number that was an order of magnitude higher than what is typically found in other papers. This has left people wondering, and a review is underway.

The European Commission is also obliged to do a cost-benefit analysis. Its report support the 2°C target. Whereas the UK analysis is sound apart from an unfortunate zero in the summary, the report by the European Commission would fail as a term paper in a course of cost-benefit analysis. In a cost-benefit analysis, one wants to equate the marginal costs and benefits, but the report only looks at total costs and benefits. In fact, the report does not estimate benefits either; it includes all impacts of climate change, not the ones that can be avoided. The impact estimates are over 10 years old, although newer and better studies are available. On the abatement side, the analysis stops in 2025, even though only a fraction of the needed emission reduction will have been achieved by then. The EU report does not review the cost-benefit literature, which reaches different conclusions. A commissioned paper that reached an opposite conclusion was similarly ignored.

I do not believe that there is anything in the literature on the impacts of climate change or the costs of greenhouse gas emission reduction that justifies the deep cuts in emissions necessary to meet the European 2°C target. However, that is not my main point. If policy makers believe that the 2°C target is justified, then they should support that with arguments. Sloppy methodology, selective citations, and exclusive input from environmental NGOs do not make for strong arguments. A democratic government should support its policies with sound science and reasoned judgements. The European climate policy falls short.

A more elaborate account of the 2°C target has been accepted for publication by Energy Policy. An early version can be downloaded here.

23 Responses to “Europe’s Long Term Climate Target: A Critical Evaluation”

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  1. Tom Rees Says:

    Interesting paper. I looked up the UK report on the Socal cost of Carbon ( http://www.hm-treasury.gov.uk/Documents/Taxation_Work_and_Welfare/Taxation_and_the_Environment/tax_env_GESWP140.cfm ). Here’s an excerpt. It seems to be in line with the body of the report. Rather than an order of magnitude higher, the ‘best guess’ is in the middle of the range of estimates cited.

    “The most sophisticated of the published studies reviewed here produces an estimate of marginal damage figure of approximately £70/tC (2000 prices) for carbon emissions in 2000. This increases by approximately £1/tC per year in real terms for each subsequent year to account for the increasing damage costs over time. The parameter values used in deriving this estimate seem to be among those enjoying the greatest support in the literature. This figure is subject to significant levels of uncertainty. Furthermore, this figure excludes any consideration of the probability of ‘climate catastrophes’ (i.e. melting of the West Antarctic ice sheet) and socially contingent impacts of climate change that could, potentially increase the size of damages considerably.”

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  3. Benny Peiser Says:

    The European conundrum is particularly illuminating given that Europeans (and most of the OECD) are likely to benefit significantly from a 2°C warming. Some environmental economists estimate that Europe’s economy would benefit to the tune of $80-120 billion p.a. from a 2°C global-mean warming in the next 50 years or so. Not bad for a “mega-disaster.”
    http://crga.atmos.uiuc.edu/publications/market_impact/MarktImp.PDF

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  5. Dano Says:

    Benny, do you have a paper (preferably published for peer review) that is less than a decade old that makes your point, or hasn’t modeling and knowledge progressed any since then?

    Thanks!

    Best,

    D

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  7. Tom Rees Says:

    Benny, the European assessment is for global impacts. Your link agrees that the overall cost of a 2 deg C change is negative (to the tune of 0.3% of GDP, or 278 billion). To be sure, Europeans (if they are confident that climate change is linear) should aim for a 2 deg C warming if they are not interested in the welfare of others. Even from a selfish point of view, however, given that the current wealth differential is creating a number of immigration problems in the EU, I’m not sure that increasing it would be a good idea.

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  9. Steve Bloom Says:

    Plus there’s the fact that they would be bequeathing to their descendants (and perhaps not very distant ones) enough sea level rise to require moving numerous major cities, including London. Of course none of the cost of that would come out of Benny’s pocket.

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  11. Benny Peiser Says:

    According to Yale University economist Robert Mendelsohn (2004), a series of studies in recent years on the economic impacts of climate change show that the older literature “overestimated climate damage by failing to allow for adaptation and climate benefits… Summing the regional impacts across the globe implies that warming benfits and damages will likely offset each other until warming passes 2.5°C, and even then it will be far smaller on net than originally thought” (Mendelsohn and Williams, 2004).

    A list of relevant, up-to-date references can be found in Mendelsohn’s written evidence (2005) to the House of Lords Select Committee on Economic Affairs
    http://www.publications.parliament.uk/pa/ld200506/ldselect/ldeconaf/12/12we17.htm

    See also Richard Tol’s (2005) comparative analysis at
    http://www.uni-hamburg.de/Wiss/FB/15/Sustainability/enpolmargcost.pdf

    Those interested to read up on the whole spectrum of views and assessments can find the evidence submitted to the UK Stern Review on the economics of climate change, at:
    http://www.hm-treasury.gov.uk/independent_reviews/stern_review_economics_climate_change/sternreview_responses.cfm

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  13. Indur Goklany Says:

    1. Richard Tol (rightly) notes that Arnell’s analyses of the impacts of water stress doesn’t allow for any adaptation. But there is an even larger problem associated with estimates of the impacts of climate change on water stress that were purportedly derived from Arnell (1999) and reported in Parry et al. (2001) and Arnell et al. (2002). The estimate that Parry et al. (2001) provide for “the additional millions of people at risk” of water shortage in the 2080s due to unmitigated global warming is in the range of 3,000-4,000 million. Arnell et al. (2002), also apparently based on Arnell (1999), provide an estimate for the “population with potential increase in water stress” of ~3,000 million (also for the 2080s). But these estimates only include the number of people for whom climate change would INCREASE water stress, but they do not subtract out the numbers for whom water stress (however defined) would be reduced.

    But fortunately, Arnell’s (1999) paper has the data that allows one to calculate the net change in the population at risk (PAR) of water stress due to climate change. In fact, if one looks at NET changes in the PAR for water stress, it’s possible that climate change might, in fact, reduce the population at risk. See the paper titled, “Relative Contributions of Global Warming to Various Climate Sensitive Risks, and Their Implications for Adaptation and Mitigation” published in Energy & Environment, vol. 14, pp. 797-822 (2003), a preprint of which can be accessed through the following URL: http://members.cox.net/igoklany/

    Arnell’s (2004) paper continues the unfortunate practice of emphasizing the increase in the population that might be subject to greater water stress, without netting out the population that might experience a decrease in water stress. But that paper also provides enough information to enable one to calculate the net change in PAR for water stress due to unmitigated climate change under various SRES scenarios. If one does that, one sees that the warmest scenario doesn’t necessarily result in the greatest population at risk for water stress, at least through 2085. This result also holds for PAR for hunger and water shortage. See: “Is a Richer-but-warmer World Better than Poorer-but-cooler Worlds?” presented at the 25th Annual North American Conference of the US Association for Energy Economics/International Association of Energy Economics, September 21-23, 2005, also at the same URL as provided above.

    2. Note that Arnell’s and Martens’ 1999 papers on water stress and malaria, respectively, were part of a larger suite of assessments of the global impacts of unmitigated climate change through the 2080s. These studies provided estimates of the additional populations at risk (PARs) for four categories of climate-sensitive hazards, namely water stress, malaria, hunger and coastal flooding. Their results were published in a special supplement to the journal “Global Environmental Change” in 1999 [Parry and Livermore (1999)]. Arnell et al. (2002) extended these studies to provide estimates of the changes in the additional population at risk under two stabilization scenarios, specifically stabilization at 550 and 750 ppm. These analyses allow us to compare the effectiveness of different mitigation and adaptation schemes in terms of reducing PAR for various climate-sensitive hazards. The results of such an effort can be found in a paper titled, “A Climate Policy for the Short and Medium Term: Stabilization or Adaptation?” [Energy & Environment 16: 667-680 (2005)], also available from the URL provided above.

    Its abstract reads as follows:

    “An evaluation of analyses sponsored by the predecessor to the U.K. Department for Environment, Food and Rural Affairs (DEFRA) of the global impacts of climate change under various mitigation scenarios (including CO2 stabilization at 550 and 750 ppm) coupled with an examination of the relative costs associated with different schemes to either mitigate climate change or reduce vulnerability to various climate-sensitive hazards (namely, malaria, hunger, water shortage, coastal flooding, and losses of global forests and coastal wetlands) indicates that, at least for the next few decades, risks and/or threats associated with these hazards would be lowered much more effectively and economically by reducing current and future vulnerability to those hazards rather than through stabilization. Accordingly, over the next few decades the focus of climate policy should be to: (a) broadly advance sustainable development (particularly in developing countries since that would generally enhance their adaptive capacity to cope with numerous problems that currently beset them, including climate-sensitive problems), (b) reduce vulnerabilities to climate-sensitive problems that are urgent today and might be exacerbated by future climate change, and (c) implement “no-regret” emission reduction measures while at the same time striving to expand the universe of such measures through research and development of cleaner and more affordable technologies. Such a policy would help solve current urgent problems facing humanity while preparing it to face future problems that might be caused by climate change.”

    References:

    Arnell, N.W., 1999. Climate change and water resources. Global Environmental Change 9, S31-
    49.

    Arnell, N.W., Cannell, M.G.R. Hulme, M., Kovats, R.S., Mitchell, J.F.B., Nicholls, R.J., Parry,
    M.L., Livermore, M.T.J., White, A., 2002. The consequences of CO2 stabilization for the
    impacts of climate change. Climatic Change 53, 413-446.

    Parry, M.L., Arnell, N., McMichael, T., Nicholls, R., Martens, P., Kovats, S., Livermore, M.,
    Rosenzweig, C., Iglesia, A., Fischer, G. 2001. Viewpoint. Millions at risk: defining critical
    climate change threats and targets. Global Environmental Change 11, 181-183.

    Parry, M.L., Livermore, M., 1999. Global Environmental Change. Special Issue 9.

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  15. Richard Tol Says:

    To Tom Rees:
    Sorry for not expressing myself more clearly.

    The report of the HM Treasure recommends a value for the price of carbon of about $100/tC.

    The median estimate in the literature is $7/tC to $33/tC, depending on the discount rate. See my paper referred to by Benny Peiser.

    HM Treasury’s estimate is obviously well within their own range. It is a bit of an outlier in the literature, though.

    HM Treasury has recognised this, and may soon revise the number.

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  17. Dano Says:

    Indur has an interesting point, but I struggle to visualize how increasing a population decreases water stress. I am unaware of any historical precedent for this assumption (that is not to say there is no evidence, just that I’m unaware of it).

    Increasing offstream uses are a tradeoff for increased industrial and economic activity – perhaps lowering economic activity will achieve this end?

    Best,

    D

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  19. Indur Goklany Says:

    Dano,

    Sorry, but I am unable to make the connection between your comment and my earlier remarks. I’m not advocating or suggesting that increasing the population would reduce impacts. [In fact, one method of reducing the population at risk would, obviously, be to reduce population, but I digress.]* Perhaps the problem is that I didn’t make my argument with sufficient clarity.

    My remarks went to the reporting of results of analyses of the impacts of climate change regarding the population at risk for water stress. Essentially the point I was trying to make is that when reporting impacts one should count not only the bad outcomes but also the good outcomes. If climate changes, then one should expect that by and large some people will end up with less water and others will end up with more (relative to a “no-climate-change” situation). Hence, one should subtract winners from losers, i.e., calculate the net change.

    Of course, with water – and I suspect with almost everything else –it’s a little more complicated. For instance, a 10% reduction in water availability in Sweden, for instance, will not have the same impact as a 10% reduction in, say, the Sahel. Moreover, in terms of impacts, a 10% decrease in available water supplies (AWS) is not necessarily equal to (but opposite in sign) to a 10% increase in AWS. One (approximate) method of dealing with this would be to specify a minimum amount of AWS per capita as being essential to meet basic human needs (e.g., 1,000 cubic meters per capita per year). Above this threshold, an area is deemed not to be under water stress, but below it, the population of that area is deemed to be under water stress. Also, there are probably a number of ways (and associated rationales) by which one can weigh decreases in AWS differently from increases in AWS – but what one can’t reasonably do is to give the former a weight of one and the latter a weight of zero under all situations, which is essentially what seems to have been done in Arnell et al. (2002) and Parry et al. (2001).

    In summary, when providing estimates of impacts (or comparing policies or whatever) we should count the good stuff, as well as the bad stuff. Otherwise, not only do we strain credulity, it can also end up justifying policies/practices that could make matters worse. This is one reason why a perfectly reasonable concept like the precautionary principle, for example, ends up (IMHO) being misused to advocate policies that are counter to advancing human well-being without commensurate improvements in environmental quality, e.g., policies such as global – as opposed to targeted — bans on DDT or GM crops. But that’s another story (but if you are interested you might, as a start, want to check out the paper at the following location: http://members.cox.net/igoklany/Nature%20Biotech%202002%20v20%201075.pdf.)

    __________

    * It would probably make sense to try to accomplish this indirectly. Consider that higher levels of economic growth are associated (for a variety of reasons) with lower birth rates. Therefore stimulating economic development should reduce the potential population at risk. At the same time, a higher level of economic development would also boost adaptive capacity (as well as mitigative capacity). On the other hand, higher economic growth might lead to higher emissions and greater warming, and so on. That’s why it’s worth inquiring whether a richer–but-warmer world is necessarily worse than a poorer-but-warmer world. I have taken a stab at shedding some light on this question and my qualified answer is that this should indeed be the case for the next few decades (assuming the latest set of global impacts analyses undertaken by Arnell, Parry and coworkers are credible). See link provided previously.

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  21. Indur Goklany Says:

    In the footnote in my previous post, it should have been “poorer-but-cooler” rather than “poorer-but-warmer.” Sorry, if the answer looked obvious!

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  23. Hugh Says:

    Indur -

    As I read it, and forgive me if I’ve missed the point.

    You suggest that 1,000 cubic metres pa/pc is the basic human need. You then suggest that areas whose supply falls below that threshold should be regarded as under water stress.

    You also suggest that some areas will see an increase in water supply and some areas will suffer increases in water stress under climate change conditions. You also use Sweden and the Sahel as examples of how the affects of water stress might differ.

    I do understand your argument against measuring good *and* bad impacts of CC. However, lets be realistic. Let’s use your stated threshold of 1,000m2 pa/pc. Why do we need to worry about the areas that, under CC, will receive increases in AWS over that threshold? That seems to me to be a case of “Water water everywhere, Nor any drop [that we are able to transport cost effectively to people who need it more than us]”

    I have not seen any project outputs that suggest that Sweden will see a DEcrease in AWS…yet the converse is true if I consider the Sahel. My point is, I do not see the justification in arguing about how some areas receiving a surfeit of AWS above the 1,000m2 pa/pc should be balanced equally against areas that fall below that supply. Water is not economically transportable over large distances, and the distance between Sweden and the Sahel (I apologise for twisting your example, but I hope I make the point) is indeed large.

    Is your argument really that it’s okay for us not to worry about future disparity in AWS because the populations of the more temperate latitudes will be getting more water than they really need…so who cares about everybody else?

    Having a high global MEAN AWS is no good to those people with none to drink.

    Regards

    Hugh

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  25. Benny Peiser Says:

    The above debate about global warming and its potential impact on water resources seems pretty emblematic for the fundamental problems inherent in most impact studies and predictions.

    Let’s look at current assessments of potential water stress. Arnell and others base their estimates on the assumption that anthropogenic global warming is and will be reducing overall water resources. But what if this basic conjecture is flawed? What, if increased levels of CO2 emissions actually increased the availability of freshwater? Believe it or not, but this counter-intuitive possibility is reported today in Nature:

    “Despite increasing human consumption of water, there was a general upward trend in continental-scale river runoff during the past century. Some researchers claim that this is due to climate change. Gedney et al. have investigated this using a mechanistic land-surface model and a statistical ‘fingerprinting’ method that allows contributions from individual factors to be identified. A climate-change driven component in runoff variation is evident, but is insufficient to account for the whole trend. A more influential factor is reduced plant transpiration due to CO2-induced stomatal closure. To date, this effect has been neglected in projections of future water resources. As CO2 concentrations rise in future, reduced plant water usage is likely to increase both the availability of freshwater and the risk of flooding, and to add to surface warming via reduced energy loss from evaporation” (Nature, 16 February 2006).

    In short, optimists reading the latest findings will ignore the “we’re-running-out-of-water” alarm. Pessimists, on the other hand, will automatically start worrying about the risk of flooding (see e.g. Fred Pearce’s article:
    http://www.newscientist.com/channel/earth/dn8727.html ).

    Cost-benefit analysis of the impact of global warming on freshwater availability, however, will have to be revised completely given that “this effect has been neglected in projections of future water resources.”

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  27. Mark Bahner Says:

    Benny Peiser writes, “Let’s look at current assessments of potential water stress. Arnell and others base their estimates on the assumption that anthropogenic global warming is and will be reducing overall water resources. But what if this basic conjecture is flawed? What, if increased levels of CO2 emissions actually increased the availability of freshwater? Believe it or not, but this counter-intuitive possibility is reported today in Nature:…”

    Yes, and this completely ignores the potential for desalination. The simple facts of desalination are:

    1) Two-thirds of the planet is covered with water (the only problem being it has salt in it),

    2) 39% of the world’s present population lives within 100 km of the sea,

    3) Worldwide water desalination increased from 2 million cubic meters in 1972 to approximately 24 million cubic meters in 2000,

    4) At least two countries (Qatar and Kuwait) already get 100% of their water from desalination,

    5) The costs for water desalination–particularly reverse osmosis, which is rapidly displacing thermal desalination–are dropping steadily. In 1960, the cost of conventional water treatment systems (i.e., for freshwater, prior to retail sale) were $0.10 to $0.50 per 1000 cubic meters. In contrast, the cost of thermal desalination of seawater averaged approximately $2.20 per 1000 cubic meters, and reverse osmosis desalination was not even commercially available. By 2000, the average cost for both thermal desalination and reverse osmosis desalination had dropped to $1.20 per 1000 cubic meters.

    http://www.mwi.gov.jo/home/Thursday/medrc.pdf

    In another 40 years, it’s easily conceivable that desalination costs will have dropped even closer to the cost of supplying treated freshwater. Does any analysis of water availability by anyone in the “climate change community” take into account the likely progress in desalination technology 40, 80, or 100 years into the future?

    That’s a semi-rhetorical question. I’m virtually certain the answer is “No, of course not. How could they scare people if they did that?”

    P.S. And I’m absolutely positive no attempt has been made by the “climate change community” to assess the possible progress (i.e., cost reduction, and increase in freshwater delivery) over the course of the 21st century for technologies like this:
    “Several companies around the world are developing technology whereby large quantities of freshwater would be loaded into huge sealed bags and towed across the ocean for sale. The Nordic Water Supply Company in Oslo, Norway, has signed a contract to deliver 7 million cubic meters of water per year in bags to northern Cyprus. During the Gulf War, Operation Desert Storm used water bags to supply water to their troops.”
    “Aquarius Water Trading and Transportation Ltd. of England and Greece has begun the first commercial deliveries of freshwater by polyurethane bags, towed like barges through waterways. The company, whose corporate investors include Suez Lyonnaise des Eaux, delivers water to the Greek Islands where a piping system links the bag to the main water supply on the island. Aquarius predicts that the market will soon exceed 200 million metric tons per year. The company’s bag fleet consists of eight 720-ton bags and two 2,000-ton versions. The larger bags hold two million liters of water each. Aquarius has completed research and development on bags ten times larger and is searching for the capital investment to produce them. The company has its sights set on Israel, and claims to have the interest of several major water companies.”

    http://www.thirdworldtraveler.com/Water/Global_Trade_BG.html

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  29. Mark Bahner Says:

    D-oh! Dangers of posting at lunchtime: Those costs were in dollars per cubic meter, not dollars per THOUSAND cubic meters.

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  31. Dano Says:

    Indur, thank you for your reply. I read it and went back and read your original comment and I better understand your argument. I think some of the misunderstanding was on my part.

    As I think you infer with your ‘Sahel’ acknowledgement and your footnote, transnational migration for many under AWS is impossible; indeed, as Americans are now seeing, those who flee environmental catastrophe stress the social fabric of the place they fled to.

    My reading of your well-constructed comments is that simply tabulating single indicators is an insufficient metric for assessing future policy options [says the ecologist]. Ecological impacts of, say, attempting to sequester increased precipitation must be considered as well. The reduced agricultural production in drier areas will lessen AWS temporarily if people migrate to other areas.

    But, certainly, the AWS and PAR metrics are excellent indicators and I can easily picture how they could be well-utilized in an adaptive management strategy, and thank you for taking the time to explain them to me. I appreciate it.

    Best regards,

    D

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  33. Indur Goklany Says:

    Response first to Hugh, then Benny with acknowledgment to Mark, and finally Dano.

    Hugh, you and Dano have convinced me that I don’t write as clearly as I delude myself into believing – one more cherished notion out the window!

    I am not sure that we have any fundamental disagreements, but additional clarification is in order from my end. Following are specific responses to your comments.

    Hugh: You suggest that 1,000 cubic metres pa/pc is the basic human need.
    Response: I offered this as an “e.g.” rather than a definitive threshold to help me think through how impacts may be counted — or not counted (see below). By the way, the 1,000 cubic m/person/yr is one of the measures that Arnell refers to [other candidates are 500, 1,700 etc., all in cubic meters/person/yr]. My understanding is that this number was originally tossed out a few years ago by a Professor Malin Falkenmark. It certainly looks good on paper, is easy to remember, is in tune with the metric system, but I can’t vouch for its sociological and biophysical underpinnings. In fact, it’s not clear to me that this should be a “universal constant” like Planck’s constant. There is probably a different number appropriate for each (sub)society depending on history, culture, dependence on agriculture, and even available water resources, etc. Thus we could have one number for the urban Germans, another for the French farmers, etc. – but let’s not go there.

    Hugh: I do understand your argument against measuring good *and* bad impacts of CC.
    Response: Thanks, that was the basic point I was attempting to make.

    Hugh: Why do we need to worry about the areas that, under CC, will receive increases in AWS over that threshold?
    Response: We only need to worry about this when keeping score of the good and bad outcomes. If, because of CC an area’s AWS (actually AWS/person/yr) goes from below the threshold to above it, it should go into the “good” column and (its population) should be subtracted from a population that goes from above the threshold (whatever it is) to below it [the latter is clearly a bad outcome]. I recognize this doesn’t address the issue of a population whose AWS is below the threshold and for which matters get worse. That’s why in my post I alluded to weighting different outcomes differently [see above]. On the other hand, if AWS substantially exceeds the threshold before and after CC, I would, along with you, not be too concerned about it. {I think the appropriate method of estimating “total impact” would be to estimate the marginal change in utility for an average population for a marginal change in AWS for each level of AWS and integrate over populations and AWS, etc. [Quite possibly, some water economist has done this kind of stuff.]

    Hugh: Water is not economically transportable over large distances, and the distance between Sweden and the Sahel … is indeed large.
    Response: That’s only partly true today, and may not be true in the future, especially if shortfalls are large and technological innovations change transportation costs over the next several decades(see Mark’s post, for instance). Even today, rich populations pay quite a lot for water that has been transported directly (as bottled water). In fact, the price of bottled water in my local store substantially exceeds that of gasoline. Rich populations also import water indirectly, e.g., in the fruits, vegetables, timber and flowers that the come from poorer countries. Similarly, rich countries export water in their wheat, corn and other grain. The real issue is whether the (implicit) water in these products is appropriately priced. And generally they aren’t because more often than not water is, unfortunately, not dealt with as an economic commodity [under the misguided notion that water is too important to attach a price to, but that's precisely why it ought to be priced -- how else to best stimulate conservation?] Doing so would help populations adjust better to changes that might be wrought by climate change, not to mention the vagaries of nature. If we can move 85 million barrels of oil and gasoline around the world each day, surely we can move water around if the incentives (and prices) are right. By the way, there are other options than moving water from Sweden to the Sahel, as Mark notes.

    Hugh: Is your argument really that it’s okay for us not to worry about future disparity in AWS because the populations of the more temperate latitudes will be getting more water than they really need…so who cares about everybody else? …Having a high global MEAN AWS is no good to those people with none to drink.
    Response: No, that’s not my argument. My remarks were about how one tallies the impacts of climate change (see above). And I do agree that a high global AWS doesn’t mean that there are no localized problems, or that we shoul ignore those problems. Your example, however, underscores the point that models should allow for adaptations, which goes back to Richard Tol’s original post (and Mark Bahner’s, as well).

    To Benny — I suspect you are right about the spin different sides will put on the Gedney et al. results. [In the days of yore, when we had a little money for extramural research, the first study I funded on CC was to look at the effect of higher CO2 levels on water use efficiency in plants and what that meant for runoff.] However, I think this latest study, if it stands up, will be specially significant for prognostications of soil moisture, and what that means for ag productivity in arid and semi-arid regions (because they have been among the foci for CC concerns). [Remember, it is the developing world in general and Sub-Saharan Africa in particular, which are most vulnerable to CC.] Moreover, despite the increased potential for floods, higher run-offs could also have some benefits, e.g., increased potential for hydroelectric (and white water rafting to compensate for declines in skiing perhaps?). I suspect, but can’t prove offhand, that it’s probably easier to do something about a situation with too-much-water than one in which there’s not-enough-water-to-grow-things-with, but of course it all comes down to costs.

    Dano, Thanks.

    Regards to all.

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  35. Rabett Says:

    Richard Tol is a professor at Hamburg, but not at the Vrije University or at Carnegie Mellon (for some reason I started to write Carnegie Million, oh well). Just follow the link. Tol is quite clear that he is a research collaborator at the other places. Not his fault, but the lily was a bit gilded in the intro here. Interesting guy.

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  37. Hugh Says:

    Indur – Thank you for your explicit rebuttal to my post, it is, I suggest, I who needs to be looking less out of the window and more at the detail of the written argument.

    Mark – I stand corrected on the ‘Sweden to Sahel’ water transfer concept. Thanks.

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  39. Mark Bahner Says:

    Hi Hugh,

    You write, “Mark – I stand corrected on the ‘Sweden to Sahel’ water transfer concept. Thanks.”

    Omigosh. I didn’t know anyone “stand(ed) corrected” these days. (I can think of two people specifically…but no need to get into that…;-))

    Anyway, you’re welcome. And thanks for thanking me.

    But while we’re at it, you certainly weren’t completely wrong…if by “Sahel” you meant, “The heart of the Sahel.” Water pipelines are (presently) pretty expensive. So the water bags (or desalination plants) can get the water to the ***coast*** of Africa reasonably inexpensively (or somewhat expensively, for present desalination plants), but getting that water into the heart of the Sahel is certainly not economical at this point…especially for Africa.

    However (see, I always have to get the last word ;;-)) the point I was making is still extremely solid. The “climate change community” routinely makes no attempt to take into account technological and economic trends. They routinely project 50 to 100 years (or more!) into the future, and pretend that the state of technology and wealth will be exactly as it is now. This is absolute and utter rubbish.

    Does 2005 look like 1905? Well, the change from 2005 to 2105 is going to be much, much, MUCH bigger than from 1905 to 2005.

    To take only one example, in my carefully researched and considered opinion, world economic growth in the 21st century is going to make world economic growth in the 20th century look like it was standing still.

    In the 20th century, world per capita GDP increased from approximately $680 to approximately $6500 (in 1990 dollars, as estimated by economist Brad DeLong).

    So even if the growth rate in the 21st century only MATCHED that factor of approximately 10, we could expect world per capita GDP in 2100 to be $60,000 to $70,000.

    But my estimate for world per capita GDP in 2100 (in year 1990 dollars) is…

    …..over $10,000,000!

    (And I am NOT kidding.)

    http://markbahner.typepad.com/random_thoughts/2003/11/i_solicited_pre.html

    http://markbahner.typepad.com/random_thoughts/2004/09/second_thoughts.html

    http://markbahner.typepad.com/random_thoughts/2004/10/3rd_thoughts_on.html

    http://markbahner.typepad.com/random_thoughts/2005/11/why_economic_gr.html

    Best wishes,
    Mark

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  41. Hugh Says:

    I asked for that didn’t I? ;o)

    Mark-

    I’m glad you clarified the challenge of irrigating the ‘heart’ of the Sahel (and continental interiors in general). In my modest gratitude I realised I’d neglected to expound on that aspect of the logistical problem (perhaps because I feared being the butt of the Bahner ‘last word’ that it might generate…D’oh!) :o )

    H

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  43. Dano Says:

    Resilience Science blog has a different look at the issue Indur discusses:

    http://resilience.geog.mcgill.ca/blog/index.php/2006/02/17/vapour-flows-soil-moisture/

    And, as we know, with an increasing population forecast that means more land devoted to agriculture [http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11303102&dopt=Abstract, http://www.pnas.org/cgi/content/abstract/96/11/5995 ], and more externalities with ag, esp. monoculture ag,; RS blog also has an entry on non-monoculture ag and how this will mitigate some of the environmental problems (esp. water quality and secondarily vapor transfer):

    http://resilience.geog.mcgill.ca/blog/index.php/2006/02/17/evaluation-of-ecosystem-services-provided-by-multifunctional-agriculture-in-the-usa/

    I’m an ecosystem services guy so there’s my bias.

    Best,

    D

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  45. Mark Bahner Says:

    “And, as we know, with an increasing population forecast that means more land devoted to agriculture…”

    “We” may “know” this. But that doesn’t necessarily mean it’s true.

    Here is a table with year, world population in billions, hectares of agricultural land required per capita, and total resulting hectares of agricultural land required, for 1950 and 1980:

    Year Pop. Area/capita Area, total
    1950 2.2 0.47 1.2
    1980 4.4 0.34 1.5

    http://www-formal.stanford.edu/jmc/nature/node10.html#SECTION00910000000000000000

    OK…so what? Population goes up, area required goes up…just as expected. But notice the area/capita went DOWN (and this occurred, even though people in 1980 were better fed than in 1950).

    Sooo…the area/capita went down by 28% [(0.47-0.34)/0.47] in 30 years. Let’s say it continues to go down at a rate of 28% every 30 years, from 1980 to 2070.

    In 2010, per/capita use is 0.25 hectares/person [i.e., 0.34*(1-0.28)]. Using a population of 6.8 billion (UN medium variant)…we get total use of 1.7 billion hectares…so more than 1980.

    In 2040, per/capita use is 0.18 hectares/person [i.e., 0.25*(1-0.28)]. Using a population of 8.7 billion (UN medium variant) we get a total use of 1.6 billion hectares…still more than 1980, but less than 2010.

    In 2070, per/capita use is 0.13 hectares/person [i.e., 0.18*(1-0.28)]. Using a population of 10 billion we get a total use of 1.3 billion hectares…LESS than 2030, LESS than 2010, and even LESS than 1980.

    This is of course just a projection, based on 1950 and 1980 data. But it illustrates why it is not NECESSARILY true that more population means more acres devoted to farming.

    P.S. My guess is that the actual trends will be even more positive than those I’ve sketched…especially for the long term. (For example, I think it was in MIT’s Technology Review where I read that chemical engineers were trying to actually create red meat (or maybe it was poultry) in a lab. Results didn’t taste very good yet, but give them a decade or two.)