versus Al Gore
|List of acknowledged errors in Gore´s
|Lomborg versus Gore|
B = The book, "An Inconvenient Truth"
F = The film, "An Inconvenient Truth"
DVDs may be purchased from this official web site. A transcript of the film is found on this web site. The transcript is not absoluteley accurate and has a few errors (e.g. "The Errol Sea" instead of "The Aral Sea").
Sources of alleged errors are listed here.
of many alleged errors, I have selected those that could be
acknowledged. In addition I list those points that need lengthy
The judgment at a British high court about 9 alleged `errors´
in Al Gore´s film is summarized here.
|LIST OF ERRORS, FLAWS AND POINTS NEEDING EXTENSIVE COMMENTS|
F, B p42: "It is evident in the world around us that very dramatic changes are taking place: This is Mount Kilimanjaro in 1970 with its fabled snows and glaciers. Here it is just 30 years later - with far less ice and snow."
What causes the ice on top of Kilimanjaro to disappear, is a complicated issue. A review of the facts and arguments is presented on this page in Lomborg-errors.
The disappearance of the ice could be due to two possible causes, or any combination of the two. One possibility is that ice disappears due to melting because of rising temperatures. This is favoured by the study group around Lonnie Thompson. The other possibility is that ice disappears only by sublimation, not by melting, and that it disappears because of reduced snowfall, so that the ice surface is less white and absorbs more of the sun´s radiation. This is favoured by the study group around Georg Kaser.
It is not settled what explanation is most correct, which means that it can not be said for certain that the disappearance of the ice cap is due to global warming, and it can not be said for certain that it is not due to global warming.
Al Gore´s presentation is obviously based on information from Lonnie Thompson. This information is that the ice cap has existed for thousands of years, but is disappearing only now. There is considerable melting on the horizontal surfaces, melting that has not happened before. Precipitation has been low also in previous periods, when the ice cap persisted, but seems to have increased in recent years, when the ice cap is disappearing. Based on these facts, it is understandable that Al Gore can conclude that the cause of disappearance is global warming. As the issue is not settled, we cannot say definitely that Gore is wrong. This is therefore not counted as a flaw. But it is unfortunate that to demonstrate global warming, Al Gore has chosen just Kilimanjaro, where the cause of the disappearance of the ice cap is not known for sure. In practically all other glaciers, their disappearance is partially due to rising temperatures, and partially due to changes in precipitation. For some tropical glaciers, changes in temperature have little influence, but for many tropical glaciers (the majority of which are found in South America), temperature has considerable influence on their gradual disappearance (link). As by far the majority of all glaciers worldwide are receding, it is obvious that global warming is a major cause. Although such recession has been underway since around 1850, the rate of glacier recession has been accelerating recently. During the years 1961-1990, melt water from glaciers and ice caps around the world, excluding Greenland and Antarctica, contributed a total of 0.33 mm per year to global sea level rise. For the years 2001-2004, the contribution was 0.77 mm per year, that is, more than twice (reference: this link). So the point that Al Gore tries to make is correct, but Kilimanjaro is one of the worst examples he could have chosen.
B p48: The book shows a large photo from 2003 of the Perito Moreno glacier in Argentina. The text above the picture is "Almost all of the mountain glaciers in the world are now melting, many of them quite rapidly. There is a mesage in this."
Perito Moreno is a bad example. Nearly all glaciers in Patagonia are receding. A survey of 95 glaciers in the Chilean part (link) showed that 6 % were advancing, 6 % were stable, and 88 % were receding. According to the wikipedia article, Perito Moreno is one of only three Patagonian glaciers where the front is not retreating. According to this paper, the Moreno glacier is the only glacier in Patagonia where the ice sheet is not thinning. It is therefore unlucky that Gore chose to use just this glacier to illustrate his point. Although he does not directly state that the glacier in the photo is receding or thinning, this is nevertheless counted as a flaw. In the film the scene is shown while Gore says: "And it is a shame because these glaciers are so beautiful", so one might argue that the scene is just used to illustrate the beauty that should be preserved. However, the judgement I make here is that because of the context in which this glacier is shown, people may be misled.
F: "In the Himalayas . . . people get their drinking water from rivers and spring systems that are fed more than half by the melt water coming off the glaciers."
(B p58): "The Himalayas . . . provide more than half of the drinking water for 40 % of the world´s population."
That part of the river flow that originates from glaciers is much less than half - it is rather 5 %. More information on the subject may be read in a report on glacier retreat in Nepal, India and China, published by the WWF. According to this report, out of the catchment area in the Himalaya and Karakorum mountain areas, about 20 % is covered by permanent glaciers, and an additional c. 40 % has seasonal snow cover. Out of the Tibetan plateau, about 4 % is covered by permanent glaciers. Most of the water in the large rivers, such as Indus and Ganga-Brahmaputra, originates from monsoon rain. Meltwater from ice and snow fields contributes only to 5 % of the annual flow of these rivers on a yearly basis, but is crucial because it supplies water in the otherwise dry seasons. So the rivers are not "fed" more than half by melt water from these areas.
In the book, the wording is different. Here it is evident what Al Gore meant, namely that more than half of the river flow originates from the mountain areas (he incorrectly writes as if the Himalayas are the same as the Tibetan Plateau). Apparently, he assumes that the mountain areas are totally covered by glaciers, but he does not write that in the book, so the flaw is only in the film.
Al Gore is right in his main point, namely that people dependent on these rivers are going to face water shortage within the next half century partially because of disappearance of ice and snow. The projected changes, according to the WWF report, are that in the upper Indus, there will be initial increases of water flow ranging from +14 to +90 % over the first few decades when the glaciers melt, followed by decreases of -30 to -90 % after 100 years. For the upper part of the Ganga, the change will be +20 to +33 % during the first two decades, and after that a decrease by -50 %. For the lower Ganga, there will be little change. For the Brahmaputra, there will be a drecrease of water flow throughout.
F: "They can go back in a lot of these mountain glaciers a thousand years. They constructed a thermometer of the temperature."
B p63: "The thermometer to the right measures temperatures in the Northern Hemisphere over the past 1,000 years."
p64: "But as Dr. Thompson´s thermometer shows, the vaunted Medieval Warm Period (the little red blip form the left, below) was tiny . . "
In Al Gore´s presentation, the audience will understand that the "thermometer" for the last 1,000 years originates from measurements of oxygen isotopes in ice cores drilled by mr. Thompson´s team. However, a confusing detail is that the graph on p. 63 shows temperatures for the Northern Hemisphere, and half of Thompson´s glaciers are from the Southern Hemisphere. What has happened is that Al Gore has used the graph in Figure 7.d in the paper on Thompson´s glaciers, and this graph does not show Thompson´s own data, but - for comaprison - the "hockey stick" of Mann et al. (1999). So what is presented here is only the well-known fact that Mann´s hockey stick shows very little warming during the medieval age.
F, B p67: Commenting on the fit between graphs of past CO2 and past temperature: " The relationship is very complicated. But . . when there is more carbon dioxide, the temperature gets warmer."
According to Gore´s opponents, his presentation imparts the conception to his audience that the observed increases in temperature are the result of increasing CO2. Gore conceals the important detail that the CO2 signals mostly lag nearly 1,000 years behind the temperature signals. This detail points to the conception that the relationship is rather the other way around: increasing CO2 is the result of increasing temperature. However, both conceptions are too simplistic. Reality is that the effect goes both ways. This is explained on the Lomborg-errors page on the CO2 lag.
It is apparent that the full explanation of what happens when temperatures and atmospheric CO2 change is very complicated. Al Gore could not possibly explain this in a popular movie. Instead he just says "the relationship is very complicated". He then jumps directly to that part which is important in the present context, viz. that more CO2 causes higher temperatures - which is correct. It would have been more correct if Gore had said that probably about half of the temperature change was caused by changes in greenhouse gases. But formally, the formulation "when there is more carbon dioxide, the temperature gets warmer" is correct, and it is also central to his theme, because he wants to conclude from the past to the future, and the message is that more CO2 will cause higher temperatures in the future. IPCC presents an estimate (wgI report, FAQ 2.1) that the present high level of CO2 gives a climate forcing of 1.7 watt/m², which is obviously large relative to the forcing of 0.7 watt/m² that is caused by changes in the Earth´s orbit.
F: About the atmospheric CO2 level: ". . here´s where it´s going to be in the next fifty years - really, in less than fifty years."
B p67: "And within 45 years, this is where the CO2 equivalent levels will be if we do not make dramatic changes quickly."
In the book as well as in the film, Gore´s presentation is confusing, especially because he uses a distorted vertical axis. In the book, there is one scale from 200 to 300 ppm, and another (more condensed) scale from 300 to above 600 ppm. This means that the projected value for 2050 appears not as high above present as it should if the scale were uniform. On the other hand, the future value is shown at 620 ppm. This is higher than projected by the IPCC for CO2, but the text says that this is the value for CO2 equivalents, which includes CH4, and therefore the figure is correct. So there are two distortions: one is the condensed scale which few will notice, and which tends to belittle the trend; the other is the shift from CO2 to CO2 equivalents which few will notice, and which tends to magnify the trend. All in all, the presentation is formally correct and the graph does not exaggerate the rising trend.
In the film, there is no mentioning of "CO2 equivalents". It is practically impossible to read the units on the vertical scale, and if one tries to extrapolate where the point for 2050 lies, considering that zero on the vertical scale is not at the bottom line, one reaches a value of about 500 ppm, which coincidentally fits well with the value projected by the IPCC.
Thus, in the film too there is no graphic exaggeration of the rising trend.
F, B p 94: "And then of course came Katrina. . . And then when it comes into the Gulf over that warm water it picks up that energy and gets stronger and stronger and stronger. . ."
Al Gore does not postulate that Katrina was caused directly by global warming. His argumentation is that when oceans become warmer in general, the hurricanes get stronger in general. That is, the risk of having a severe hurricane increases, but you cannot speak of direct cause and effect. Al Gore does suggest that the warm water in the Mexican Gulf at that particular occasion did contribute to making Katrina grow as strong as it did. This seems quite plausible. It has been suggested that the high surface temperatures in the Gulf at that occasion did extend unusually far down into deeper water layers, and the amount of heat mobilised when deeper water was sucked up into the cyclone made it possible for the hurricane to grow exceptionally strong. The risk that the deeper water would have been so warm is obviously larger when we have global warming.
Therefore, it seems that there is no flaw in Al Gore´s argumentation here and that the judgment made by the high court in London on this particular point (read here) is not warranted.
F: "The insurance industry has actually noticed this. They´ve recorded losses are going up. You see the damage from these severe weather events."
B p102: "The insurance industry is one business sector that´s already feeling the unmistakable economic impact of global warming. . . As one business leader put it, insurance companies face "a perfect storm of rising weather losses, rising global temperatures, and more Americans than ever living in harm´s way."
The increasing economic losses reflect mainly that more and more property is subject to damage, and more and more people live in high risk coastal zones. The are not "unmistakable". When the trends are adjusted for these changes, there remains no long-term trend during the 20th century. This is explained e.g. by Lomborg in "Cool it!". Therefore, although Gore´s presentation is not formally wrong, it is nevertheless misleading. The small reservation "more Americans living in harm´s way" is not enough to prevent this from being counted as a flaw.
B p106: " . . the number of large flood events has increased decade by decade, on every continent." Illustration titled: "Number of major flood events by continent and decade."
The chart illustrating the rise in flood events is taken from page 448 of the Millenium Ecosystem Assessment report, Eco-Systems and Human Well-Being. The graphic presentation has been changed, but it is an approximately correct reproduction of the information, except that the original chart was labelled "Number of recorded flood events by continent and decade in twentieth century", whereas Gore´s book has the wording "Number of major flood events". Now, the word `major´ might suggest something about the physical magnitude of meteorological events, but that suggestion is spurious, as pointed out in the CEI criticism of the book. Actually, the chart presents the data from the EM-DAT global disaster database at the university at Louvein in Belgium . As explained on page 447 of the Millenium Ecosystem Assessment report, only events that are classified as disasters are reported in this database. An event is declared as a disaster if it meets at least one of the following criteria: 10 or more people are reported killed; 100 or more people reported affected; international assistance was called; or a state of emergency was declared. The rising trend from 1940 onwards may partially be due to increased reporting of actual events, and partially to changes in socioecoomic systems, such as growth of cities along rivers (which is stated in the report). In addition, it is obvious that with increasing population sizes, the risk that at least 100 people will be affected by a flood of a given size is greatly increased. Gore does not mention these caveats.
All in all, there is little or no indication that the average frequency or physical magnitude of floods has actually increased during the 20eth century.
IPCC states (FAR wg2, chapter 1) that there is no evidence for at climate-related trend in floods. Increasing damages have been due to increasing vulnerabilities. Therefore, the graph presented by Gore is so misleading that it will count here as a flaw.
See also the comments to the incidence of wild fires (p. 229 in Gore´s book).
F: ". . Lake Chad, once one of the largest lakes in the world. It has dried up over the last few decades to almost nothing."
B p117: "But now, due to declining rainfall and ever-intensifying human use, it has shrunk to one-twentieth its original size."
The drying up of lake Chad (shrinking from 25,000 km² in 1963 to 1,350 km² recently) is most probably caused by several factors working in concert. Overgrazing reduces the vegetation cover, and the reduced vegetation cover means less evaporation of water and hence less precipitation of condensed water vapours. With less and less precipitation, human and animal populations have come to rely more and more on water from the lake. Massive irrigation projects to combat the drier climate diverted water from both the lake and the two main rivers that empty into it, the Chari and the Logone. In addition to these effects, there has also been a climate change, i.e. reduced rainfall, in the region during the latter half of the 20th century. Anada Tiega of the Lake Chad Basin Commission blames climate change for 50 to 75 percent of the water's disappearance (link). According to a study of Hoerling et al. (2006), the change in rainfall is related to higher sea surface temperatures in the southern Atlantic relative to the northern Atlantic. In that study, this difference between the southern and the northern Atlantic is most probably not a consequence of global warming. But other sources state that the reduced rainfall can be simulated by computer models that incorporate an increasing greenhouse effect, see here or in the IPCC wgI report, FAQ 3.2. This means that the drying of the region during the latter half of the 20th century is part of a global climate variation, but it is uncertain if it is connected to global warming. Global warming may or may not in the future lead to more warming of the southern than the northern Atlantic. The El Nino phenomenon also has some role to play in this, and unfortunately existing computer programs cannot model the El Nino phenomenon.
Does Al Gore properly represent this state of information? The voice in the film says: ""And focus most of all on this part of Africa, just on the edge of the Sahara. Unbelievable tragedies have been unfolding there, and there are a lot of reasons for it. But Darfur and Niger are among those tragedies. And one of the factors that has been compounding them is the lack of rainfall and the increasing drought. This is Lake Chad, once one of the largest lakes in the world. It has dried up over the last few decades to almost nothing, vastly complicating the other problems that they also have." It is apparent here that Al Gore pays due regard to the multifactorial character of the problems, and does not directly postulate that any particular phenomenon is due to global warming. In the book, he clearly states that the drying up is due both to declining rainfall and to intensifying human use. This too, is a balanced presentation. Although the example is presented in a context of global warming, it is not said that global warming caused the problem. Therefore, it seems that the judgment made by the high court in London on this particular point (read here) is not warranted.
F: About ice cores from Antarctica: " . . right here is where the US Congress passed the Clean Air Act . . you could see the difference with your naked eye."
B p139: "Yet another surprise for me was when scientists showed me that near the South Pole, the presence of air pollution in the ice cores visibly declined not long after passage of the US Clean Air Act in 1990 . . you can actually see the before and after with your own eyes."
Changing atmospheric pollution on the Northern Hemisphere would leave no signs on Antarctica. According to IPCC, 4AR wg1 paragraph 126.96.36.199., "Data from ice cores show that sulphate aerosol deposition has not changed on Antarctica, remote from anthropogenic sulphur dioxide sources". See also this page on Realclimate. To cite Bob Edelman: "I will give Gore the benefit of the doubt and say that he was the victim of a joke." But, joke or not, you may say that the public is being misled.
(F): ". . for the first time they are finding polar bears that have actually drowned, swimming long distances up to 60 miles to find the ice."
B p146: "A new scientific study shows that, for the first time, polar bears have been drowning in significant numbers. Such deaths have been rare in the past."
The presentation in the film is OK, but the book has the wording "in significant numbers", which is hardly correct.
There are limits to how far polar bears can swim in open water. When the sea ice melts away faster than usually, and the bears roaming there need to head for firm land, they may have to swim longer distances than before. In September 2005 an unusually high number of bears were found swimming in the Beaufort Sea north of Alaska. Just then came a storm, and after the storm scientists observed the carcases of 4 drowned bears. This has not been observed before (and not since then). See more details in this link.
The crucial point is that the bears are forced to swim longer distances than before, and therefore are at a greater risk if a storm comes. When Gore presents this episode as something that will happen more frequently in the future, he may be wrong, but most likely he is right. Therefore, it seems that the judgment made by the high court in London on this particular point in the film (read here) is not warranted.
On the other hand, the book says "in significant numbers". Four bears in one single episode is hardly significant in any way, and this is therefore counted as a flaw.
F: "Is there any other big chunk of ice near there? [referring to Greenland] Oh Yeah! "
B p 149: "10,000 years ago . . . the Gulf Stream virtually stopped. . . Consequently, Europe went back into an ice age for another 900 to 1,000 years . . . Some scientists are now seriously worried about the possibility of this phenomenon recurring."
"Dr. Ruth Curry is especially concerned about the rapid melting of ice in Greenland . . Recently, she observed: `The possibility of such extreme events precludes ruling out that disruption of the North Atlantic conveyor in the 21st century could occur as a result of greenhouse warming.´"
What IPCC says about this, is as follows (wgI report, section 10.3.4 and FAQ 10.1). They speak of the "Atlantic Meridional Overturning Circulation (abbreviated MOC; also referred to as the thermohaline circulation) and write: "Taken together, it is very likely that the MOC . . will decrease . . but very unlikely that that the MOC will undergo an abrupt transition during the course of the 21st century." And they write further that most models agree that the amount of water circulated by the MOC will decrease by somewhere between an insignificant amount and 50 % by 2100. No model shows an abrupt change before 2100, but some long-term model simulations suggest that a complete cessation can result for large forcings. Thus, an abrupt change after 2100 cannot be excluded. The changes will not completely prevent that the warming of Europe continues.
Does Al Gore´s presentation agree with the scientific consensus as expressed by the IPCC? The phrasing in his book that "some scientists are seriously worried" can hardly be denied, provided that by "this phenomenon recurring" we refer to the halt of the Gulf Stream, not Europe going back into an ice age. Concerning the film, Al Gore is ironic and very unprecise. He says: "Of course that´s not gonna happen again because the glaciers of North America are not there and . . Is there any other big chunk of ice near there? [referring to Greenland] Oh Yeah! We´ll come back to that one." So he indirectly suggests that melting of the Greenland ice could do more or less the same to the termohaline circulation once more, but he gives no clue to the likelihood or extent of such a scenario. He does not suggest a complete repetition of the scenario from 10,000 years ago. Thus, formally there is nothing wrong in his presentation.
B p 149: "10,000 years ago . . . the Gulf Stream virtually stopped. . . Consequently, Europe went back into an ice age for another 900 to 1,000 years . . . Some scientists are now seriously worried about the possibility of this phenomenon recurring."
Gore writes about an episode in the past when the Gulf Stream stopped, and writes that this might recur. There has been some criticism that he writes `Gulf Stream´ when what would actually stop would be the thermohaline circulation. This is important, critics say, because the Gulf Stream is driven by wind, whereas the thermohaline circulation is driven by differences in sea temperatures and salinity. They claim that if the thermohaline circulation stopped, the Gulf Stream would not stop, and cooling of Europe would probably not happen. This criticism is partially a dispute over words; the common understanding of the Gulf Stream, especially in Europe, is that it includes the extension of this stream towards Europe, an extension called `the North Atlantic Drift´. This drift is mainly driven by the thermohaline circulation. If that stopped, that wind-driven part of the Gulf Stream would bend off and not continue northwards, which means that the northern half of Europe would indeed become cooler. In a film and book like this, some popularization is unavoidable, and also for this reason the conflation of the two systems is acceptable.
B p 150: "Dr. Ruth Curry is especially concerned about the rapid melting of ice in Greenland . . Recently, she observed: `The possibility of such extreme events precludes ruling out that disruption of the North Atlantic conveyor in the 21st century could occur as a result of greenhouse warming.´"
The quote from Ruth Curry could not be found on the internet. There were other quotes to be found which are generally less scaring and some of which explicitly state that Europe will not cool. As Gore does not give the source of the quote, it is not known if it is correct. In an email (10 Jan 2008) Ruth Curry writes: "I don´t remember if I used the word "disruption". But if I did, it was in the context of a slowing of the heat-bearing currents flowing northward of Iceland-Scotland, not a complete stoppage of flow." She further writes that at the time that the Gore team was assembling the scientific evidence presented in "An Inconvenient Truth", there was genuine and justifiable concern over what was being observed in the North Atlantic. But the 30-year trend of freshening in the northern North Atlantic reversed around the year 2000, and looking back it is now clear that the freshening did not have a sustained impact on the Ocean Conveyor.
F: "Coral reefs all over the world because of global warming and other factors are bleaching . . All the fish species that depend on the coral reef are also in jeopardy as a result."
B p 166: "The link between global warming and the large-scale bleaching of corals, considered controversial only 10 to 15 years ago, is now universally accepted."
The bleaching of corals is treated by IPCC in the 4AR wg2 report, in several paragraphs. Paragraph 1.3.4 says: "There is now extensive evidence of a link between bleaching . . and sea surface temperature anomalies." and "In 1998, the largest bleaching event to date is estimated to have killed 16% of the world´s corals . . On many reefs this mortality has led to a loss of structural complexity and shifts in reef fish species composition . . ". Paragraph 6.2.5 and box 6.1 say: "Global warming poses a threat to coral reefs, particularly any increase in sea surface temperature. The synergistic effects of various other pressures, particularly human impacts such as over-fishing, appear to be exacerbating the thermal stress on reef systems and, at least on a local scale, exceeding the thresholds beyond which coral is replaced by other organisms." "Coral bleaching, due to loss of symbiotic algae and/or their pigments, has been observed on many reefs since the early 1980s. . . If bleaching is prolonged, or if sea surface temperature exceeds 2°C above average seasonal maxima, corals die. . . Recent preliminary studies lend some support to the adaptive bleaching hypothesis, indicating that the coral host may be able to adapt or acclimatise as a result of expelling one clade of symbiotic algae but recovering with a new one . . . Corals and other calcifying organisms . . remain extremely susceptible to increases in sea surface temperature."
It appears that Al Gore´s presentation is fully in accordance with the general scientific view as expressed in the IPCC report. Therefore, it is strange that the judgment made by the high court in London (read here) does not fully reject objections to this point. The judge states: "The actual scientific view, as recorded in the IPCC report, is that, if the temperature were to rise by 1-3 degrees Centigrade, there would be increased coral bleaching and widespread coral mortality, unless corals could adopt or acclimatise . . ". That is, in the judge´s opinion, coral bleaching is something that might possibly happen in the future if sea temperatures rise, but not something that is already a severe problem. It thus seems that the judge has been very much misled, and that his statement is not warranted.
Actual dying-off of corals is by now well documented. In Wilkinson (2004): Status of coral reefs of the world (link), it is said that 16 % of the world´s reefs were seriously damaged in 1998, but that 6,4 % are recovering, leaving 10 % permanently dead. It is also said that "The coral bleaching in 1998 was a 1 in a 1000-year event in many regions with no past history of such damage. Also very old corals around 1000 years old died during 1998. Increasing sea surface temperatures and CO2 concentrations provide clear evidence of global climate change in the tropics, and current predictions are that the extreme events of 1998 will become more common in the next 50 years." It should be added that we are not just talking about singular events. There is, in addition, a gradual decline. Wilkinson (2004) shows a chart that the coverage of coral reefs in the Caribbean declined from 54 % cover in 1976 to 9 % cover in 2001. Thus on a longer time scale, there is a very severe decline. In the light of this, Al Gore has not exaggerated the severity of the situation.
F: "There are cities that were founded because they were just above the mosquito line. Nairobi is one. Harare is another. There are plenty of others. Now the mosquitoes with warming are climbing to higher altitudes."
B p173: " . . the mosquito line, which used to mark the altitude above which mosquitoes would not venture." "Before 1970: cold temperatures caused freezing at high elevations, and limited mosquitoes and mosquito-borne diseases to low altitudes."
If the `mosquito line´ is understood as a line above which there are no mosquitoes, then both presentations (film and book) are clearly wrong. Nairobi was not founded with regard to the distribution of mosquitoes, and was not free from malaria. However, the distribution of malaria in time and space is a complicated issue whcih is discussed more thoroughly on this page in Lomborg-errors. It appears from this that after 1970, malaria has become gradually more frequent in the Kenyan highlands, and a series of severe epeidemics occurred during the 1990s. Slight temperature increases since 1987 may have contributed to the latter, but the rise just after 1970 is more likely due to other causes, with no contribution from climate. In general, however, it is true that the incidence of malaria decreases with altitude, and that there are increases in incidence which may be explained by increases in temperatures in the most crucial months. Thus, because the main point in Gore´s presentation is probably correct and only the details are wrong, this is counted only as a flaw.
F, B p174: "We´ve had 30 so-called new diseases that have emerged in just the last quarter century." Diseases referred to in the book and/or the film are Dengue fever, Lyme disease, West Nile virus, arenavirus, Machupo virus, avian flu, Ebola virus, Marburg hermorrhagic fever, E. Coli 0157:H7, Hantavirus, Legionella, Leptospirosis, multi-drug-resistant TB, Nipah virus, SARS and Vibrio Cholerae 0139.
Gore gives the impression that the emergence of these diseases is related to global warming. In the book on page 173 he writes: "Global warming pushes all of these boundaries in the wrong direction, thereby increasing human vulnerability to new and unfamiliar diseases." It is true that warmer climates may promote the spread of certain infectious diseases, especially malaria and dengue fever. For instance, as explained in the Lomborg-errors page on malaria in Kenya, even a slight increase in temperature may markedly increase the infection rate of the malaria parasite, or change conditions from periodic infections to permanent infections. It is also true that climatic change or unusual climatic conditions may give some contribution to the greater spread of leptospirosis and hantavirus pulmonary syndrome (link), in addition to lyme disease, legionnaires´ disease, Vibrio cholerae 0139 and possibly West Nile virus. But concerning ebola, arena virus, SARS, E. coli 0157:H7, avian flu, Nipah virus and multiresistant tuberculosis, the contribution of climate change to their spreading seems to be close to nil. To indicate that these diseases will spread because of global warming seems to be scare tactics and has so little to do with confirmed evidence that it is here counted as an error.
F, B p175: "One example is the West Nile Virus, which entered the United States on the eastern shore of Maryland in 1999. " "Two years later, it was across the Mississippi. And two years after that it had spread across the continent. These are very troubling times."
The West Nile Virus probably arrived in the United States via an aircraft. The chance that it could get foothold may have been increased a little by global warming leading to slightly more favourable conditions for the virus in Maryland. However, once the virus had become established, it was able to spread all over the US, in widely different climates. An organism may require more optimal conditions for getting a new foothold than for spreading from a core area. So it is theoretically possible that it would not so easily have become established with lower temperatures. But as there is practically no concrete evidence for such a possibility, this is counted as a flaw.
F, B p183: "Scientists thought that the Larsen-B ice shelf would be stable for another century - even with global warming."
Comment: Critics pose that the breakup of ice shelves is not due to man-made global warming, because these ice shelves have disappeared before. This criticism is unjustified. The Larsen-B ice shelf has existed without interruption since the ice age (Domack et al. 2005, Curry & Pudsey 2007), and its breakup is ascribed to man-made global warming (Marshall et al 2006). Also the IPCC report (4AR wg1 paragraph 188.8.131.52) says: " . . the ice shelf changes have resulted from environmental warming . . "" Before the 2002 breakup of the Larsen B Ice Shelf, local air temperatures had increased by more than 1.5°C over the previous 50 years .. increasing . . formation of large melt ponds on the ice shelf. These likely contributed to breakup . . ". Gore´s argument that the breakup was unexpected is that the effect of these melt ponds had not been understood previously. It may be added that air temperatures in the Antarctic Peninsula region have risen by over 2.5°C in the last 50 years.
F: "That is why the citizens of these Pacific nations have all had to evacuate to New Zealand."
B p186: (showing a photo from one of the Tuvalu islands) "Many residents of low-lying Pacific nations have already had to evacuate their homes because of rising seas."
The wording in the film would imply that at least several Pacific nations were by now completely evacuated, with no people left. This is obviously far from the truth. The wording in the book would imply that many had already evacuated. This is hardly so. There are serious threats to a number of islands in the nations of Tuvalu, Kiribati and the Marshall Islands, and two uninhabited islands in Kiribati have disappeared (link). In 2001, New Zealand made an (informal?) agreement to take 75 Tuvaluans a year as part of its Pacific Access Category, and many Tuvaluans have emigrated to New Zealand or Australia, for various reasons - in some cases for fear of rising sea levels (links here, here and here). Up to now, the movements have had the character of voluntary emigration rather than forced evacuation.
Whereas global sea levels are rising as a general trend, the sea surface is not absolutely stable and horizontal, and there are areas where sea level rise has not yet occurred. The sea at Tuvalu is one of the places where sea level has not risen recently. Therefore, there is no new emergency situation up to now.
All in all, Al Gore´s presentation is not 100 % wrong, but it is dramatized to such an extent that it is counted here as a full error.
F, B p189: Gore presents a graph showing that annual closures of the Thames barriers increased in recent years.
Critics claim that the more frequent closures have nothing to do with rising sea levels; they claim the reason is a change of policy by which the barrier is closed during exceptionally low tides, so as to retain water in the tidal Thames rather than keeping it out. The critics are completely wrong, however. For instance, one of the statements on the official Thames Web says as follows: ""Today's closure sets a landmark for the number of times the Barrier has closed to protect London from flooding and serves as a stark reminder that living in the floodplain is never without risk. The rise of sea levels is a reality, and although we are closing the Barrier at the forecast rate, we expect closures to happen more frequently with 30 closures a year being the norm in 2030 if we don't make changes to the current system."
F, B p190: " . . air temperatures high above the ice have warmed more rapidly than air temperatures anywhere else in the world."
Gore correctly cites a study by Turner (2006). The critics stress some uncertainties, e.g. that some model runs do not replicate the observed tropospheric warming over Antarctica, but it should be remembered that there are other model runs that do replicate observations. In any case, actual observations are more important than model projections. It is also worth remembering that critics over and over again claim that whereas models predict more warming in the troposphere than at the surface, such warming has not been observed. Now, here is a case where we do have (much) more warming in the troposphere than at the surface, and what do the critics say? The say that this isn´t warming at the surface, so it doesn´t count! In any case, melting of all that ice on Antarctica takes heat out of the air, so maybe it is no wonder that air temperatures there rise very little.
F, B p196: "IF Greenland broke up and melted, or if half of Greenland and half of West Antarctica broke up and melted, this is what would happen to the sea level . . ." "sea levels worldwide would increase by between 18 and 20 feet."
Formally, Al Gore´s statement is correct. IF that amount of ice melted, sea levels would rise by the indicated amount. In the film, the word IF is pronounced with emphasis. So we are talking of a hypothetical scenario. Gore makes no indication as to when this could possibly happen; there is no clue indicating that it should be in the near future. On various skeptics websites it is postulated that Gore suggests that this would happen before 2100. This postulate is completely unwarranted. He does not suggest that.
A good reason for Gore to be vague here is that it is uncertain how fast these ice masses will melt in case of continued unabated rise in CO2 levels. A plausible estimate is that about half of the ice of Greenland would have melted away in a thousand years from now. If also half of the West Antarctic ice mass would melt, Gore´s scenario could be true at around the year 3000. But it might also happen faster. New evidence since data were gathered for the latest IPCC report is that melting of sea ice and land ice in the Arctic is proceeding somewhat faster than anticipated. Summer sea ice on the North Pole might disappear much earlier than previously anticipated; this will increase the albedo, which is very important for the acceleration of the warming. So the conception that the 6 m rise in sea level might come earlier than in 3000 is not completely unfounded.
Another objection to the plausibility of Gore´s 6 m sea level rise is that much of the land ice on Greenland remained in place during the previous interglacials, even though temperatures then reached higher levels than now. But Gore´s point is that the present situation is unprecedented - there have never during the preceding interglacials been CO2 levels approaching the high levels to be expected already during the 21st century. So we do not expect a simple repetition of what happened during the previous interglacials.
The scenes showing flooding of densely populated areas might be called scare tactics, but I believe the audience will generally understand that these scenes are hypothetical.
For these reasons, the attitude taken here is that Gore´s presentation on this point is OK.
B p229: "The graph below shows the steady increase in major wildfires in North and South America over the last five decades; the same pattern is found on every continent as well."
Just the like graph on changes in flood events (see above for p. 106 in Gore´s book), the graph on changes in fire events is taken form the Millenium Ecosystem Assessment report (page 449) and based on the EM-DAT global disaster database at the university at Louvein in Belgium. Gore´s presentation shows only the increase in the Americas, which is the most dramatic, whereas increases in other continents are more moderate. The chart in the original report is designated "Number of reported wild fires by continent and decade in the twentieth century". This has been relabelled "number of major wildfires" in Gore´s book. Contrary to what is stated in the CEI criticism of Gore´s book, this relabelling is justified, as the original report does use the term "major fire events" in its text. It is explained in the text that although the area burnt in USA has declined by 90 % from 1930 to now, the average annual number of major fires increased markedly to about 10 in the 1980s and about 45 in the 1990s. A large part of the explanation for this discrepancy is that when efforts to suppress fires succeed on a short term, the amount of wood that potentially could burn increases (the fuel load), and this increases the likelihood that when a fire finally breaks out, it will be catastrophic. The trend for more fires on average in Europe (except Sweden and maybe other northern countries) seems to be real. In Europe as a whole, the total extent and the interannual variability of the area of burnt forest are higher for the period 1975-2000 than for the 1960s. This statistic involves physical measures rather than damage to human values, and therefore the rising trend seems to be real.
Al Gore has taken data on floods and wildfires from the same report, and treated them in the same way. For floods, the result is misleading. For fires, it is not.
B p252: (On emissions trading) "The European Union has adopted this US innovation and is making it work effectively."
Flaw: Although the trade with emissions functions, it has had no effect on CO2 emissions on a European scale up to now. The sum of the permits handed out is larger than the sum of actual emissions. This situation is hardly described by the wording "making it work effectively."
F: "They took a big sample - 10 percent - 928 articles . . the number of those that disagreed with the scientific consensus . . zero!"
B p262: "Naomi Oreskes . . . She and her team selected a large random sample of 928 articles representing almost 10 % of the total . . "
The Oreskes article is summarized correctly. However, its conclusions have been challenged by several others, as may be read here. For instance, dr. Benny Peiser in UK has replicated the study and found that out of 1117 article abstracts, 34 rejected or questioned the view that human activities are the main driving force of the observed warming over the last 50 years. However, a closer inspection of those 34 abstracts (see here) reveals that only two of them reject present man-made global warming, and one of these is a petroleum industry publication. A few others express doubt whether man-made global warming is real; these are mainly from the early or mid 1990s. Altogether, Oreskes´ conclusions seem warranted, and Gore´s presentation on this point is OK.
As pointed out by several critics, the 48 scientists were part of a political agenda. To cite CEI: ". . the scientists in question are members of `Scientists and Engineers for Change´, a 527 political group set up to promote the Kerry for President Campaign. Indeed, the June 21, 2004 letter to which Gore refers and from which he quotes is first and foremost an andorsement of John Kerry for President." It would have been most correct if Gore had mentioned this (or not used the letter in his book).