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Reading notes : The Skeptical Environmentalist

September 2003

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The Skeptical Environmentalist

Bjorn Lomborg


60 for the chapter on climate


Cambridge University Press

Expert of the subject, to detect all the bad faith


Important note : this page just discusses the "climate change" chapter of Lomborg's book. I have not read the other chapters.


The writings of M. Lomborg have a point of superiority over those of many "anti-global warming activists" (for example M. Stott) : obviously he has read - or had his possible ghosts read, which is the same - part of the scientific litterature on the subject. If the writings of other authors (I mostly have french references up to now, sorry...) reveal a knowledge at best vague, and generally non-existant, of what the scientific file contains, this is not the case for Lomborg, that gathered information on the subject, but is a master at twisting this information to get to wrong conclusions from true facts (probably voluntarily).

M. Lomborg has written a book which has the same aspect than a classical scientific book, with many illustrations and quotes (other "skeptics" generally produce purely litteral stuff, without a single chart or figure), and many technical discussions on this or that part of a curve. This expert talk and the similarities with "classical" scientific litterature opportunely allow to abuse all individuals that are not familiar with the topic, journalists obviously constituting prime preys considering some elogious critics seen in the general press (available on Lomborg's web site).

It is nevertheless possible to find, in Lomborg's book, the same fallacious logics or mere nonsense that can be found in the litterature of some of his "brothers of arms". A first category of these could gather some very "classical" points :

Lomborg feigns to believe that the concerned scientists are liable for the exagerate or inexact assertions made by journalists or activists, just because the latter claim they faithfully transcript the words of the first (which is of course not the case). This enables to put in the scientist's mouth many things that they did not say, or did not say the same way (these people, like me, appreciate nuances and precision, which require space that papers don't always have), or said in a context which is not given. Two examples among others : Lomborg quotes the Los Angeles Time (which is not a scientific paper, up to now at least !) regarding the cold fusion (page 321), or "the press" for the IPCC scenarios (page 280).

The IPCC would have voluntarily put apart, without examination, plausible theories explaining that the main cause of the temperature increase of the past decades is "natural variability". One theory, among others, is put forward in Lomborg book : the importance of the sun (page 277). In order to allow the reader to understand (if not, just skip this part and trust me !), the theory in question was for example exposed by two researchers named Svensmark and Friis-Christensen, in an article wrote in 1997 ("variation on cosmic ray flux and global cloud coverage - a missing link in solar-climate relationships", Journal of Atmospheric and Solar-Terrestrial Physics,1997, 1225-1232), that noted a correlation between the sun's activity and the global temperature for 15 years and suggested the following chaining of events (I have added some elements not cited but obvious for the writers - but maybe not so obvious to anyone) :

variations in solar activity generate a variation of the magnetic field of the sun (this is exact),

this magnetic field exerts a significant influence in the neighbourood of the earth (exact),

our planet is permanently bombed by a flux of highly energetic charged particles coming from outer space, named cosmic rays (exact),

these cosmic rays transmute gases in the high atmosphere and turns them into solid elements, that are labelled cosmogenic referring to their formation (exact, it is this way that beryllium 10 is formed, of which the concentration in ice cores is used to reconstitute insulation for ancient times),

when the magnetic field of the sun varies, it modifies the trajectories of the particles of the cosmic rays near the earth (any magnetic field influences the trajectory of a charged particle) and hence the intensity of the bombing of earth, and therefore the formation of cosmogenic elements (exact).

it is necessary to have impurities in the air - called condensation nucleus - in order to enable the formation of water droplets that constitute clouds from water vapour (exact),

cosmic rays variations - linked to the variations of the solar activity - lead to a variation of the number of solid particles in the air, and from there to a variation of the cloud cover (this is actually the speculative part).

It happens that after a discussion arouse in the scientific then general press on this theory, the authors of the initial publication published a complementary article (Reply to comments on "variation on cosmic ray flux and global cloud coverage - a missing link in solar-climate relationships", Svensmark & Friis-Christensen, Journal of Atmospheric and solar-terrestrial physics, 62 (2000), 79-80), in which they write :

that micro-physics of clouds is not well known (the IPCC report says nothing different),

"a possible effect of the cosmic ray flux cannot be ruled out".

But "cannot be ruled out" is not equivalent to "is clearly established" ! Though this second article was published in 2000, that is 2 years before Lomborg's book, it is not taken into account in Lomborg's discussion on the role of the sun, which sticks to the much more affirmative formulation of the first, when Lomborg has no particular competence in physics that would allow him to do so.

more generally speaking, when hundreds or thousands of articles have been published on a given matter, Lomborg bases most of his reasoning on a very small selection of them, doing exactely (by dismissing all that does not please him) what he otherwise accuses (wrongly) the IPCC of doing !

But this book has many other errors. Here is a restricted selection :

Lomborg deliberately ignores the precautions exposed by the authors of some results he quotes, and substitutes probabilities for certainties. For example the possible evolution of agricultural output in a modified climate (page 288), is presented as an established result, when agronomists present their results with a long list of what they have not taken into account, and insist that nobody can talk of "forecasts". The IPCC considers that predictions for crop yields are associated with a "medium to low confidence", but Lomborg doesn't care : he treats them as if they were certain. And the most comic thing is that these agricultural simulations are based.....on the very same climatic simulations that Lomborg will have harshly criticized a couple of pages earlier !

page 279, he mixes up the IPCC emission scenarios with other scenarios (of the PCMDI programme). The latter never had the ambition to reflect a probable evolution of the greenhouse gases emissions, but Lomborg discusses at if it where the case,

page 280 and after, he criticizes the IPCC emission scenarios (he basically lists all the reasons why things could happen differently, what all involved people generally know well, and what - surprisingly - Lomborg sometimes omits to do when he bases his own demonstrations on other scenarios !) but mixes up hypotheses with conclusions. Emission scenarios are by nature hypotheses for simulations, not conclusions. He may dicuss them if he likes (I also did) but he may not present them as forecasts resulting from a thourough study of the future, or as evolutions presented as more probable than others, since it is not the case (the authors do not state that they are more probable than anything, or do not rank them by probability of occurring) and that they are only considered as plausible (which means that nodody can rule them out, but that's all). In other terms M. Lomborg tries to punish the authors for an error they did not make.

As soon as there is an uncertainty, he interprets it as favourable to his cause, that is that reality will probably be better than the described situation. But one should not consider ignorance as a warranty that nothing will happen : ignorance is just ignorance, and the reality may prove better than what we considered as likely, but also worse !

Lomborg mixes avoided danger and unjustified fear : in some past cases regarding environment, if a "catastropha" did not happen it is not necessarily that we got afraid for nothing, but it may also have been that the danger was avoided by a preventive measure..

and at last he has a strong tendancy to judge our past behaviours only on the grounds on the already visible consequences, just as if those that are future but certain were without importance. In other terms he deliberately ignores the inertia of physical processes when estimating the consequences. If we listen to him, we can say that smoking is not dangerous because all smokers are still alive !

As it is possible to find something false or inexact in almost any paragraph, I will stop here, otherwise the list would become boring, and there are other interesting things to say on this book. Indeed, some other surprises come with the economic part, where it is possible to find many times the application of what I would call "Lomborg"s law", which could be stated as : "any extrapolation is valid when it suits me".

Extrapolating is a classical way to reason as soon as we are curious about the future. For example, if I establish that the energy consumption has risen of 2% par year for a century, I can consider as a plausible hypothesis that this trend will go on for the next 10 years and "predict" the consumption in 10 years by adding 2% per year starting from now. It's this way of reasoning that is called extrapolating. It is equivalent to considering that the laws of evolution in the future will remain the same to what they were in the near past.

When we establish a "forecast" for air trafic, road trafic, life expectancy, or the consumption of shoes of every inhabitant of the Philippines, it's exactely what we do : an extrapolation, not a forecast in the true sense of the word.

But such reasonings are not always valid. For example, my kids have grown about 6 cm per year since they were born. Am I authorized to say that in 30 years they will be 3 meters tall ? Or of an employee earns 2% extra every year but is 3 years from retirement, can I say that he will earn 20% more in 10 years ? And if I woke up alive evey day since my birth, am I immortal, which is a logical consequence if I can prolongate in the future, without limits, the rule that says "I woke up alive every day in the recent past" ?

I could multiply the examples, but the reader will have understood (well I hope so !) : after each extrapolation, it is necessary to verify that the result is not absurd compared to the other knowledge that we have. For example, supposing today that the energy consumption can increase by 2% per year for a century is not compatible with the data now available on reserves.

Well a close examination of Lomborg's writing shows that everytime or almost that he attempts an extrapolation, the announced results are not valid. Three examples among others :

Lomborg indicates that the price of renewable energy decreasing by 50% every 20 years, all we have to do is wait until they become so competitive they will naturally substitute oil (and therefore CO2 emissions will naturally decrease). But Lomborg either really ignores or feigns to ignore that the price of renewables is not independant from the quantity produced (the most favourable places for dams - therefore the cheapest - are taken first, for example), and on the other hand these renewables do not necessarily have an infinite potential : increasing indefinitely the quantity produced is not possible, whatever market price there is, and renewable energy production will remain too low to allow the substitution of all oil, coal and gas presently consumed in the world.

We should not fear about the extension of the endemic zone of malaria because this extension will happen polewards, affecting rich countries that will be able to manage the problem without major consequences in 2080 (page 292). What does M. Lomborg know of what will remain of our present adaptation capacities in 2080 ? Why restrict the problem of vector borne diseases to the single case of malaria ? Why doesn't he say a word of the spreading of pests of all kind ?

Lomborg doesn't fear to affirm that the difference of global temperature rise with Kyoto and without Kyoto would be 0,15 °C in 2100. This means that he knows for sure - because temperatures in 2100 depend on the evolution of greenhouse gases emissions until then - how the world will behave after 2010 if Kyoto is enforced, and how the world will behave until 2100 if Kyoto goes to the paper basket. Of course he doesn't know it. He just extrapolated after 2010 the evolution of the emissions before that year, with or without Kyoto. Nostradamus had better give up : competition is too brilliant !


Regarding economy, his main argument is that fighting against global warming will cost a lot of money, and that rather than wasting all this money for speculative dangers, we'd better give it to the poor (the poor is a rising value among "skeptics") ; that as the world becomes richer the consequences will be manageable without pain, that we know what we spend but not what we earn, etc.

As some of his french brothers of arms, Lomborg seems to ignore that all an economic modelization does is adding an additional layer of hypotheses on the representation of the physical world, with the result that such a modelization sums the uncertainties on the evolution of the real world with the uncertainties linked to the purely economic hypotheses.

For example, if we try to estimate the price of freshwater in 2050, in order to know how to behave today, we must :

predict the evolution of the resource, therefore know what the pluviometry will be in 2050 for all concerned zones (physical world),

predict what the number of potential consumers of freshwater will be in 2050 (physical world)

but also.....know what rule will allow to link the price to the available ressource and the number of consumers, and there is no scientific truth in the way to chose this link (in the way that there is not just one possible way to do it).

Could we, in this example, first criticize the results of the "physical" model that will predict the amount of freshwater per person in 2050, then assert that the price of water in 2050, resulting from "economic modelisations" (that are based on the physical data !) does not justify to do this or that ?

It is though exactely what Lomborg is doing, as do all the "skeptics" I have ever read, when he invokes economic elements to justify that we should not take any measure to reduce the greenhouse gases emissions : he forgets that the economic elements he invokes are partly the result of "physical" simulations ! And anyway as nobody is able to estimate how much we could loose if we didn't act, this whole discussion of how much it costs not to loose is pointless.

In short this chapter combines a discussion on the scientific data of climate change, for which the author is not qualified, with a debate on the attitude we should have facing this risk, where he is perfectly entitled to an opinion, but not to pretending that he knows what policy is appropriate in the name of economy, that only represents part of the reality and does not know how to give an objective and non debatable value to our climate.


Bjorn Lomborg is professor of statistics in the political science department of the university of Aarhus, in Denmark. I don't know what he is worth as a statistician, but he never published a single article in the scientific press regarding climate change. His website mainly insists on his public life, when the curriculum of any university research worker generally mentions first his publications in the specialized press (but Lomborg doesn't have a single one in the domain he discusses, and is not very talkative on his "professionnal" publications in statistics or political economy).

I can't help asking myself these two questions regarding this author :

his book has several thousands quotes, probably refering to an important number of papers and books (I just had a copy of the climate change chapter, without the notes). As Lomborg is not paid to criticize the IPCC or to read stuff on climate change or on any other environment problem, but to teach statistics, where did he find the time to read several thousand references he quotes ? Is this book really the work of a lone man ? If not, who helped him, when, how, why, and "paid" how ? If yes, once again, when did he find the time to read the litterature he criticizes or invokes ?

Lomborg is said to be a former member of Greenpeace, but I still haven't understood in what circumstances he had left. If he really is a former member of Greenpeace, to what extent didn't he publish this book to settle his account with some former "collegues", as systematic criticism is generally the sign of an "affective" motivation ?


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