MECHANICSVILLE, Va. -- From what I see in Lindzen's latest "critique," of climate change believers published in the June 26 Wall Street Journal (http://online.wsj.com/article_print/SB115127582141890238.html), he's got some problems with facts. He has made a number of statements contradicted by recent scientific studies. I review some of these troublesome statements here.
I will begin with the Arctic. Lindzen says, "the Arctic was as warm or warmer in 1940; that icebergs have been known since time immemorial; that the evidence so far suggests that the Greenland ice sheet is actually growing on average. . ."
Lindzen could have checked the data as I have. The extent of the Arctic pack is decreasing overall, with the greatest declines in the Northern Hemisphere summer months, which is the time of greatest heating in the Northern Hemisphere. The extent of summer ice is at its lowest since 1900! It has been steadily decreasing since about 1950.
This is critical to the northern hemisphere climate as sea ice reflects most sunlight that strikes it and stays cool. Open water absorbs most sunlight that strikes it (and correspondingly warms). Water changes temperature slowly, and stores the heat absorbed -- to depths of several hundred meters as opposed to a few meters on land. The absorbed heat is then released slowly, so that the time of first freeze comes later over time, and the first thaw comes earlier.
With a shorter frozen period, the ice pack likewise shrinks. Smaller ice packs melt more quickly, thus exposing more open water to sunlight for longer periods. More heat is absorbed, and on. The system is a positive feedback in which a change in one direction enhances further change in that direction.
Some studies (such as Polyakov et al., 2003) do indicate that temperatures were warmer in the Arctic in the 1940s than in the 1990s. What Lindzen did not mention, which is significant, is that almost all of the weather stations selected in the study were on land. The critical action, however, is over the ice cap -- over the ocean -- where we have almost no long-term data.
In Polyakov’s study, involving 75 climate stations, nearly two-thirds were SOUTH of 60 degrees North Latitude. From their map, I estimate about a third were located between 70 degrees and 80 degress. I counted only five north of 80 degrees. Since the Arctic Circle lies at about 66.5 degrees North latitude, I surmise that less than half of their stations are truly in the Arctic.
The observational data are as follows: Arctic ice thickness is decreasing; The extent of Arctic ice is decreasing; The annual duration of Arctic ice is decreasing; Arctic water temperatures are warming. Fundamental physics -- the thermal properties of water -- indicate that Lindzen is on thin ice with respect to his comments on the Arctic.
With respect to Greenland, all the studies I am aware of indicate that Greenland is losing rather than gaining ice. If the Greenland ice pack is "growing" it is only in the horizontal dimensions. Glaciers near water often spread out as they melt -- meltwater lubricates the ice contact with rock below and allows them to slide downslope more easily.
Lindzen needs to be reminded that glaciers are three-dimensional objects. In the vertical dimension, Greenland's ice pack is getting thinner. In fact it is losing volume. In other words, the Greenland ice pack is shrinking rather than growing. Thus begs the questin, how can the Greenland ice pack be growing while losing anything from 30 to 80 cubic kilometers per year (Kerr 2006). Inquiring minds want to know.
With respect to sea-level rise, a recent study (Overpeck et al., 2006) says: "Polar warming by the year 2100 may reach levels . . . that were associated with sea levels several meters above modern levels. . ." For the metrically challenged out there, two meters is a little more than six feet. During the time period that was compared to present in the study, sea levels were as much as six meters above current sea level. That's about 20 feet. I doubt all of that rise could be achieved in less than 100 years, but a two- or three-meter rise would be devastating to many coastal communities -- such as New York City.
Lindzen failed to mention that alpine glaciers had been in retreat since the end of the Little Ice Age -- which coincidentally ended in the early 19th century. Anyone who knows climate history knows his failure to mention that significant climate milestone is disingenuous. What he also failed to mention is that the rate of glacial retreat has accelerated -- in some cases dramatically -- since the 1930s.
It is true that glaciers in some regions are advancing -- an increase in precipitation (ironically driven by global warming) can alter the mass balance in some regions so that glacial growth occurs. But the truth is that most alpine glaciers are retreating (see http://www.grida.no/climate/ipcc_tar/wg1/fig2-18.htm). Some are in danger of disappearing altogether. Many high-elevation ecosystems are in danger of disappearing, too, because the climate is changing too rapidly for species to adjust. Alpine tundra -- the pretty stuff in many David Muench photographs -- is especially vulnerable, as the tundra will likely be overrun by subalpine forest before sufficient soil forms at higher elevations (soil formation is a slow process at any elevation) to allow tundra plants to get a toehold in the areas exposed by retreating glaciers.
With respect to malaria, Lindzen should review the scientific literature. I had no trouble finding two recent studies (Pascual et al., 2006; Zhou et al., 2004) that found links between climate variability and malaria incidence. For example, Zhou et al., writes "Significant change in climate variability has coincided with increased magnitude . . . and frequency of malaria epidemics since 1989. . . [A]nalysis found that monthly rainfall and maximum and minimum temperature were significantly correlated with monthly malaria incidences. . ."
Sure, as Lindzen says, malaria has been a problem in much of the United States in the past. Mosquitoes do not need tropical temperatures to survive, as anyone who has been in the Arctic in the summer can attest. But Lindzen ignores basic biology -- warmer temperatures and longer seasons lead to longer periods of activity for insects and other disease vectors, which can lead to increase incidence of the diseases they carry. Warmer temperatures and longer seasons allow species limited to the tropics and subtropics to expand their range into temperate -- even subpolar regions -- which can lead to spread of diseases into areas where they have not previously occurred.
Lindzen’s argument about linking specific hurricanes to global warming is a red herring. If there is only one climate scientist who claims such, why bother refuting such tripe? Nevertheless, warmer sea surface temperatures will lead to increased intensity of storms, if not increased frequency. The physics is pretty basic -- warmer water temperatures lead to greater evaporation, greater evaporation leads to more water vapor in the air, more water vapor in the air leads to greater instability, and greater instability leads to stronger or more frequent storms. Of course, many things affect the development of hurricanes and other tropical storm systems, but it all begins with evaporation from surface waters.
As for what Lindzen calls the lassitude argument, which in essence says that something is happening, we cannot explain it, therefore it much be human-induced climate change, the most recent IPCC report used statistical techniques to detect the influence of human activity on climate. While people may quibble with the statistical procedures used, the claim of human interference is clearly based on firmer ground than, "I don't know what else it can be."
Lindzen seems to have a difficult time acknowledging that humans can exercise significant influence on natural ecosystems. He should spend more time hanging out with unemployed fishermen along the New England coast who have overfished and depleted the source of their livelihood.
Now I'll address Lindzen's credibility as to the Oreskes study. In Oreskes's study (Oreskes 2004) -- which is only ONE page long -- she wrote that she analyzed "928 abstracts, published in refereed scientific journals between 1993 and 2003, and listed in the ISI database with the keywords 'climate change.' "
In comes Benny Peiser. He says ONLY 913 of 928 papers had abstracts to examine. (Maybe we should launch a Congressional investigation into scientific misconduct!) Many readers may not know that an "abstract" is a term of art for scientific publications -- a very brief summary of an article, printed at the top (often in smaller type), that allows scientists to get the gist of an article before they decide to read the rest of it. Abstracts are a hell of a time saver for a busy scientist.
So 15 of Oreskes's source articles have no abstract. That's less than two percent of the total number of articles she consulted. Did they have a summary? Is reading the summary materially different from reading an abstract? No. If some or all of the 15 articles had no abstract or summary, could Oreskes have done what most scientists do -- actually read the body of the 15 papers to learn what they said?
Does this discrepancy in reporting her methods affect Oreskes’s results? Of course not! She had a sentence in which to describe her methods. She did a pretty good job, I think. No scientist, not even the great Lindzen himself (probably not even Peiser), reports all the tweaks needed to make raw data usable. To put it bluntly, this is a non-issue.
Next, let’s evaluate the discrepancies in Oreskes's and Peiser's results. Here is what Oreskes wrote:
"Of all the papers, 75 percent . . . either explicitly or implicitly accept[ed] the consensus view; 25 percent dealt with methods or paleoclimate, taking no position on current anthropogenic climate change. Remarkably, none of the papers disagreed with the consensus position."
Peiser wrote a letter to Science in response to Oreskes's paper. In the letter (http://www.staff.livjm.ac.uk/spsbpeis/Scienceletter.htm) he makes another petty complaint: Oreskes made a mistake in reporting the search terms she used to locate relevant papers for her study. She originally wrote that she searched for articles mentioning "climate change" -- which turned up more than 12,000 references in the source database. She instead used the term "global climate change," which turned up about 1,000 references. Oh my, what double-dealing! (Actually, the term "global climate change" is a more relevant term.)
Peiser modified the categories used to classify papers, which makes direct comparisons with Oreskes’s paper difficult. He claims that only 13 of 1117 studies (one percent) from the period 1993-2003 explicitly endorsed the consensus view that humans are causing some form of climate change. I am pretty sure I could find quite a bit more than that just mining Peiser’s data. He says that only 40 percent either explicitly or implicitly endorsed the consensus position, and that 57 percent were neutral to the consensus position -- a figure more than twice as high as Oreskes reported.
He the clams that 34 of 1117 studies either rejected or expressed doubt about the consensus. (Note that Oreskes's used the category “reject” rather than “reject and doubt.”)
Peiser's modifications of categories, his inclusion of op-ed pieces, and his own judgment (of which I cannot judge, being that considerable subjectivity, including his own, is involved) may have innocently produced the differences he describes between his and Oreskes’s results.
To get to the 34 “reject or doubt” studies, Peiser included op-ed pieces and commentary in addition to scientific studies. Oreskes included only scientific studies.
Peter Norvig, on his Web site at http://www.norvig.com/oreskes.html, reported the results of his own investigation into the discrepancy (I have edited out citation numbers):
"Of the 34 articles, I would say that [two] clearly reject the consensus, but they are editorials, not scientific papers (and [one of those] is from an oil industry trade association). [Two] doubt, but again are not scientific papers. [three] and maybe [one other] doubt, and [one] says that both greenhouse gases and solar activity are roughly equal contributers [sic] to warming; so I counted it as 'doubt' but it is close to 'reject.' So overall I would say that Oreskes is correct; that Peiser has not shown a peer-reviewed scientific paper that clearly rejects the consensus. I would also say that Peiser is correct in that he found at least 4 papers that place some doubt on some of the premises of the consensus, but he is widely wrong in claiming 34."
A list of the Peiser 34 can be found at http://timlambert.org/2005/05/peiser/.
Peiser ultimately concluded:
"This is not to deny that there is a majority of publications that, although they do not empirically test or confirm the view of anthropogenic climate change, go along with it by applying models based on its basic assumptions. Yet, it is beyond doubt that a sound and unbiased analysis [in other words, Peiser’s analysis] of the full ISI databank will find hundreds of papers (many of which written by the world's leading experts in the field) that have raised serious reservations and outright rejection of the concept of a "scientific consensus on climate change". The truth is, that there is no such thing!"
From my own observations as a scientist I think it is safe to say that Peiser is wrong about the lack of consensus. Scientists (like myself) can be a disagreeable lot, but our disputes are often over minutia rather than major concepts.
Peiser ends his letter to Science by requesting that Oreskes's paper be withdrawn. Science neither withdrew Oreskes's paper, nor did it publish Peiser's letter (a sound decision, in my opinion).
I'm glad to see that Lindzen acknowledges that more greenhouse gases lead to more heat trapped in the atmosphere, but I reject his assertion that carbon dioxide is a minor greenhouse gas. The primary greenhouse gas in the atmosphere is of course water vapor, but carbon dioxide is probably No. 2 on the list, followed by methane, nitrous oxides, and CFCs.
According to the National Oceanic and Atmospheric Administration (http://www.cmdl.noaa.gov/aggi/), the amount of radiative forcing -- essentially, the amount of heat trapped in the atmosphere by a particular gas, or, in this case, the amount of additional heat trapped in the atmosphere by an increase in a particular gas -- carbon dioxide accounts for 1.7 watts per square meter (W/m^2) of the Earth's surface. This is the increase over the forcing due to additional carbon dioxide since 1750. The forcings from other greenhouse gases (besides water vapor), are 0.5 W/m^2 for methane, 0.16 W/m^2 for nitrous oxide, 0.23 W/m^2 for CFCs, and 0.086 W/m^2 for other greenhouse gases.
I think it is clear that carbon dioxide is far from a minor greenhouse gas.
To close, I think it is important to revisit Lindzen's conclusions as stated in the Wall Street Journal piece.
1) Lindzen, as a scientist, should spend more time trying to achieve an understanding of climate science, rather than claim that an adequate understanding of climatic processes is too difficult to achieve.
2) Lindzen acknowledges that increased greenhouse gases can affect the climate. He denies, however, that humans can have significant effects on the climate, despite the fact that we are the major source of greenhouse gas emissions on this planet. His logic, such as it is, escapes me.
3) He should be careful in making accusations that others try to establish truth by repeated assertion. I vaguely remember some proverb about glass houses and stones.
REFERENCES (not otherwise linked to in text).
Kerr, R.A. 2003. A worrying trend of less ice, higher seas. Science 311: 1698-1701.
Oreskes, N. 2004. Beyond the Ivory Tower: The Scientific Consensus on Climate Change. Science 306: 1686.
Overpeck, J. T., B. L. Otto-Bliesner, G. H. Miller, D. R. Muhs, R. B. Alley, and J. T. Kiehl. 2006. Paleoclimatic Evidence for Future Ice-Sheet Instability and Rapid Sea-Level Rise. Science 311: 1747-1750
Pascual, M., J. A. Ahumada, L. F. Chaves, X. Rodo, and M. Bouma. 2006. Malaria resurgence in the East African highlands: Temperature trends revisited. Proceedings of the National Academy of Sciences 103: 5829-5834.
Polyakov, I. V., R. V. Bekryaev, G. V. Alekseev, U. Bhatt, R. L. Colony, M. A. Johnson, A. P. Makshtas, and D. Walsh. 2003. Variability and trends of air temperature and pressuremin the maritime Arctic, 1875-2000. J. Climate 16: 2067-2077.
Zhou, G., N. Minakawa, A. K. Githeko, and G. Yan. 2004. Association between climate variability and malaria epidemics in the East African highlands. Proceedings of the National Academy of Sciences 101: 2375-2380.
