Lomborg-errors: "Cool it!"
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Comments to pages 87 - 92 in Cool It!
| IS THE
GULF STREAM BI-STABLE ?
| WHAT IS
THE RISK FOR A SHUTDOWN OF THE ATLANTIC OVERTURNING CIRCULATION ?
Flaws on particular pages in Lomborgs text:
Note to page 87: "This is the story Al Gore tells . . . although he gets the timing wrong." Comment: Lomborg has misunderstood this. The episode that Gore refers to is the onset of the period called the Younger Dryas about 11,500 years before present (rounded by Al Gore to `around 10,000 years ago´. This event was the start of a cold period lasting 900 to 1,000 years. It is different from the episode referred to by Lomborg at about 8,200 years before present.
Page 87 bottom: "an unprecedented amount of fresh water flooded the North Atlantic . . . " Comment: In the previous episode at about 11,500 years ago, which marked the start of the period called Younger Dryas, the amount of fresh water released was probably much larger.
Page 87 bottom - 88 top: "This pushed Europe into a little ice age for almost one thousand years." Flaw: Lomborg confuses the episode at 11,500 years ago and that at 8,200 years ago. The formed caused a return to an ice age climate for another thousand years. The latter caused relatively smaller temeprature drops for about 400 years.
Page 88 top: ". . . the IPCC expects Greenland to melt almost one thousand times less . . . " Error: The figure of a thousand times is calculated by Lomborg and is not to be found in any IPCC publication. The basis of the calculation can only be seen in the British version of Cool It. Lomborg takes the very lowest of all the IPCC estimates for the melting of Greenland ice during the 21st century (this figure corresponds to the amount of melt water that Greenland already now dumps per year, as an average of various studies (A.Cazenave &W. Llovel (2010): Contemporary sea level rise. Annual review of marine science 2: 145-173)). The amount of water released into the sea at the event 8,200 years ago was, according to Lomborg´s source, about 200,000 km³. This would suffice to raise the world´s sea level by 60 cm. The maximum estimate of how much ice melt from Greenland could contribute over a century, in case of very rapid global warming, is also 60 cm (6 mm per year, according to the one of Lomborg´s sources, Stouffer et al. (2006)). So the fresh water pulse at the event 8,200 years ago is not a thousand times the expected fresh water pulse from Greenland; rather it is about the same size as the very largest (and not very likely) forecast for the fresh water pulse from Greenland during 100 years from now on.
Page 88: " . . . what would happen if Greenland melted at triple the rate expected by the IPCC . . . " Comment: Lomborg gives us the impression that the model study is at the upper extreme of what the melt rate could be, and probably three times the most likely melt rate. This is indeed what is stated by the authors. Actually, concerning the rate of Greenland melt, the authors use a base scenario (A1B) which yields a contribution to sea level rise of 10 cm during the 21st century. A tripling of the basic rate would mean a contribution to sea level rise of 30 cm during the 21st century. This is approximately the same size order as the IPCC maximum estimate if we include the possible effexts of increased flow of ice sheets due to lubrication of their base. In addition, the authors note that whereas some models are relatively sensitive to changes in the fresh water fluxes, their model is not so sensitive. The reasons for such differences between models are not very well understood. In any case, the effects to be expected are probably small relative to certain other models.
Page 88: " . . . who put the theory forward one week before world leaders met in Japan . . . " Comment: Lomborg infers that the theory was more or less invented in order to affect the political process in Kyoto. But Broecker published his theory in Nature in 1985, more than ten years before the Kyoto meeting. However, it is true that Broecker did publish another paper in Science in 1997 at the time of the Kyoto meeting.
Page 89 top: "In 2004, Fortune magazine revealed . . . " Comment: The article in Fortune did include certain caveats. It said that scientists generally refuse to say much about abrupt climate change, citing a data deficit, and it tells that the scary scenario was produced by non-scientists. It also says: "It doesn't pretend to be a forecast. Rather, it sketches a dramatic but plausible scenario to help planners think about coping strategies."
Page 89 top: "Now the Pentagon tells Bush . . . " Remark: Lomborg is right in criticising the article in The Observer, which goes much too far in painting a world-wide disaster which apparently "will" happen soon.
Page 89: " . . and by 2020 Europe´s climate is more like Siberia´s " Comment: It is obvious from the part of the text cited by Lomborg that this does not include South Europe, and on the next page of the document, it is said that this refers to Northwest Europe. The temperature drop by 2020 is indicated as 6° F (= 3.3° C).
Page 89: "Aggressive wars are likely to be fought . . . " Comment: The whole idea of the Pentagon report is to produce a scenario in which certain types of conflict and war would arise, in order that Pentagon could think over how they would prepare for such eventual events. The whole thing is conceived as a thought experiment, in which the exact dates are just inserted to dramatize the account. If no wars had been included in the scenario, it would not have fulfilled its purpose.
Page 90 top: "Yet, the problem with these terrifying forecasts . . . " Flaw: They are not forecasts. The authors of the Pentagon report write: "Rather than predicting how climate change will happen, our intent is to dramatize the impact climate change could have . . ". The Fortune article explicitly said "It doesn't pretend to be a forecast". And nobody will be in doubt that The Day After Tomorrow is a piece of fiction, not a forecast.
Page 90 top: " . . .Europe probably cooled some some 2.7° F . . " Comment: Lomborg´s main source for this event, Barber et al. 1999, say 2.7 - 5.4° F for northwest Europe.
Page 90 top: " Model estimates project the same kind of drops from future disruptions . . . " Comment: Lomborg is very unprecise here. What kind of disruptions? However, the sources given in the note give an indication. Stouffer et al. (2006) deal with two scenarios. One is a moderate and rather likely situation - a 30% reduction of the Gulf Stream, which would reduce temperatures on continental Europe by 0.5-1.0° C, and somewhat more in Britain; the other is a complete shutdown of the northern branch of the Gulf Stream, which would cause temperature drops of about 4° C in central Europe and up to 10° C (18° F) in northwesternmost Europe. These are very drastic drops, giving conditions reminding of an ice age. The other study is Wood et al. (2003). For a total shutdown of the northern branch of the Gulf Stream, they get immediate temperature drops of 3-5° C in Britain and less on the continent.
Page 90: " . . . the MIT ocean physicist Carl Wunsch . . . " Comment: The reader´s letter that Wunsch wrote to Nature in 2004 was overstated. Wunsch is right that since the winds will continue to blow and the Earth continue to turn, the energy source for the Gulf Stream will remain. But as stated in the general comments on top of this page, this relates only to that part of the Gulf Stream which stretches up to about 30° N. North of that, the northgoing branch of the current, which feeds the Meridional Overturning Circulation, is more sensitive to changes in various forces, and this branch may be affected by man-made climate change. See also the comments to Wunsch here. Furhtermore, it remains true that it is not unthinkable that the Meridional Overturning Circulation may shut down, as demonstrated by reconstructed prehistoric events and indicated by certain model runs.
However, the letter (which was repeated in an issue of the Economist) made him popular among climate skeptics, and was probably a main reason why he appeared in the film `The great global warming swindle´. However, Wunsch subsequently protested against the way he was used in that film, and the filmmakers had to make a revised version in which he was cut out. In a declaration printed in Science no. 328, May 7th 2010, p. 689, it is said that: "There is complete, comprehensive, and consistent objective evidence that humans are changing the climate in ways that threaten our societies and the ecosystem on which we depend." Among the many scientists who signed this declaration is Carl Wunsch.
Page 90 bottom: "The headlines were predictable . . ." Comment: Lomborg wants to give the impression that several public media try to overdramtize and to scare its readers. Is this impression true? Not quite. Some media report the story without proper reservations. This was the case for The Independent. The Times had an article focusing on negative news, but did remember to state at the end that the data from 1992 and 2004 could be mere aberrations. Also, National Geographic remembered to write that it is too early to say if we are just seeing natural variability, and that there is no reason for immediate concern. Sydney Morning Herald wrote that not enough measurements had been made to rule out natural variability. New Scientist (3rd Dec. 2005) quotes Bryden that he is not yet sure if we see a long-tem trend. BBC News (30th Nov 2005, link) has a large paragraph with the heading `Natural variation´, stating that the the trend could be down to natural variability. Altogether, out of six media, only one forgets to mention the necessary reservations. Considering the usual standard in public media, this is not very bad.
Page 90 bottom: "New Scientist chose the news as one of its top stories from 2005 . . " Comment: New Scientist had a lengthy and not very misleading article on 3rd Dec. In a review of the main news of the year on 24th Dec. (this is the one referred to by Lomborg), they had a much shorter notice, in which the Gulf Stream issue took up only five lines. This short notice mentions that there is a ´worry´, but does not stress the uncertainty further than that.
Page 91 top: " . . . which included a reference to The Day After Tomorrow". Comment: The reader will probably believe that the reference to this film is yet another part of the sensationalism and scare-mongering. It is nearly the opposite. Twice in the article, the journalist stresses that The Day After Tomorrow is not realistic. She writes "Researchers have dismissed the idea the climate would ever change as rapidly as depicted in The Day After Tomorrow".
Page 90-91: Altogether, the whole paragraph starting with "The headlines were predictable . . ." gives an impression of the media coverage which is not accurate and somewhat misleading.
(COMMENT) FLAW COMMENT ERROR
Page 91: "In New Scientist the headline was . . . ": Comment: New Scientist had a lengthy article on the subject already on 15th April 2006 by Stephen Battersby.
Page 91: "None of the current models simulates an abrupt reduction or shut-down." Flaw: Lomborg has truncated the sentence. The original sentence is: "none of the current models simulates an abrupt reduction or shut-down in this century." The missing three words at the end of the sentence are important and should not have been left out.
Page 91 bottom: " . . . but no models show a complete shutdown." Comment: See the paragraph at the top of this page titled: WHAT IS THE RISK FOR A SHUTDOWN OF THE ATLANTIC OVERTURNING CIRCULATION ? Here it is said that the cited text refers only to the most complicated models, the AOGCMs, and that these may all be flawed in one crucial respect. There are a number of models of intermediate complexity (EMICs) that show a complete shutdown. In the most sensitive models (which are not more unrealistic than any others) a fresh water flux of little more than 0.1 Sv suffices to cause a shutdown of the circulation, and a fresh water flux of that size order is not unthinkable at the end of the 21st century or some way into the 22nd century. So although the risk of a shutdown is small, it is not zero.
Page 92: "As the IPCC points out, Europe will still warm, even if the Gulf Stream shuts down completely" Error: The source for this statement is the 4th IPCC report (its question 10.2), but IPCC did not exactly say this. Their text is about "a gradual reduction of the MOC that continues even after climate is stabilised". As to what will happen in case of a clear-cut shutdown of the northern branch of the Gulf Stream, we know that Lomborg has consulted two papers on this issue by Wood et al. from 2003 and 2006. He ignores what is said in these. They present a run with one of the advanced models (an AOGCM), in which a shut-down of the Gulf Stream is forced upon the model in the year 2049, following upon the degree of warming that has occurred up to that point. The result is shown in figures in these papers and is referred to as follows in the text: "We see that around the North Atlantic, the cooling effect of the THC change more than outweighs the effects of global warming, leading to a net cooling relative to the pre-industrial climate in those regions." and in another place: ". . . such a shutdown would return northwestern Europe in particular to a climate that was substantially colder than pre-industrial, and the pontential rapidity and unpredictability of such a change could make adaptation particularly difficult." To put the predicted temperature drops of up to 3-5° C in Britain in perspective, they mention that during `the Little Ice Age´, average temperatures in central England were cooled by about 0.5° C. So the model´s cooling is much, much worse than in the seventeenth and eighteenth centuries. This part of the presentation was also referred to by an article in the Guardian that Lomborg has read. Considering that Lomborg has read the papers by Richard Wood et al., and has read the Guardian article, it is gross sloppiness that he overlooks this.