Woodwell (1989), for example, wrote that "the changes expected are rapid enough to exceed the capacity of forests to migrate or otherwise adapt. Davis (1989) said that "trees may not be able to disperse rapidly enough to track climate." Gear and Huntley (1991) claimed that "the maximum [migration] rates attainable by ... long-lived sessile organisms [are] more than an order of magnitude less than those required to maintain equilibrium with forecast anthropogenically induced climate changes," while Root and Schneider (1993) stated that "changes in global climate are expected to occur ... too fast for evolutionary processes such as natural selection to keep pace," and that such constraints "could substantially enhance the probability of extinction of numerous species."

Dyer (1995) echoed these sentiments, stating that "the magnitude of the projected warming is considerable; the rate at which it is predicted to occur is unprecedented," and that there is thus "genuine reason for concern that the extent of range shifts will exceed the dispersal abilities of many plant species." Malcolm and Markham (2000) agreed that "rapid rates of global warming are likely to increase rates of habitat loss and species extinction [since] many species may be unable to shift their ranges fast enough to keep up with global warming." Malcolm et al. (2002) concurred that "migration rates required by the warming are unprecedented by historical standards, raising the possibility of extensive, and in many cases, catastrophic, species loss." Root et al. (2003) repeated the mantra that "rapid temperature rise and other stresses ... could ... lead to numerous extirpations and possibly extinctions." And Parmesan and Yohe (2003) suggested that the CO2-induced global warming extinction phenomenon was already underway, with its initial effects being manifest in numerous "mini-migrations" of plant and animal populations throughout the world.

Obviously needing something better than these mere declarations to promote their concerns, the world's climate alarmists eventually began to produce biological models that supported their claims. One of the first groups of scientists to do so in a really big way was Thomas et al. (2004), who developed projections of future habitat distributions for over one thousand different plants and animals, which they used to produce estimates of extinction probabilities associated with Intergovernmental Panel on Climate Change (IPCC) climate change scenarios for the year 2050.

Prior to the publication of their paper, Thomas et al.'s results were widely disseminated to the popular media, which generally portrayed them as first-rate scientific findings that depicted the inevitable annihilation of over a million unique species, if anthropogenic CO2 emissions were not quickly and dramatically reduced. This news was viewed by many opponents of fossil fuel usage as yet another opportunity to browbeat humanity in an attempt to get the world community of nations -- and the United States in particular -- to accept their demands for draconian reductions in the development and use of these CO2-emitting energy sources.

The nineteen scientist-authors of the paper that created all the fuss began their analysis by determining the "climate envelopes" of a total of 1,103 species. Each of these envelopes represented the current climatic conditions under which a given species was found in nature. Then, after seeing how the identically-defined habitat area of each of the studied species would be expected to change in response to an increase in temperature (most habitat areas declined), they used an empirical power-law relationship that relates species number to area size to make their final extinction probability calculations.

At first blush, this procedure seems reasonable enough, all else being equal. But "all else" is almost always not equal when something changes in the real world; and the case in point is no exception. Accompanying a CO2-induced increase in air temperature, for example, there is always -- by definition -- a concomitant increase in the air's CO2 concentration; and this concurrent phenomenon, the physiological effects of which on earth's plants were totally ignored by Thomas et al., has some critically important consequences that dramatically alter their conclusions. In fact, these consequences actually refute their conclusions.

The key fact ignored by the nineteen scientists (which demonstrates there is little strength in numbers when it comes to discerning truth from error) is that plants in a CO2-enriched atmosphere generally prefer warmer temperatures than they do when exposed to air of the current CO2 concentration. Many experiments convincingly demonstrate, in this regard, that a doubling of the air's CO2 concentration typically boosts the optimum temperature for plant photosynthesis by several degrees Centigrade, and that it raises the temperature at which plants experience heat-induced death by about the same amount, as is thoroughly documented and discussed in our major report The Specter of Species Extinction: Will Global Warming Decimate Earth's Biosphere? And, of course, extra CO2 in the air generally always leads to greater rates of plant photosynthesis and biomass production (see the Plant Growth Data section of our website), as well as a heightened ability to successfully deal with most naturally-occurring environmental stresses and resource limitations (Idso and Idso, 1994).

As a result of these CO2-induced changes in their basic physiological behavior, earth's plants would not be eliminated from large portions of their current natural habitats near the heat-limited boundaries of their ranges in a CO2-enriched world of the future -- even if temperatures were to rise as high as is unrealistically predicted by climate alarmists -- because most types of vegetation, with the help of the extra CO2, would be able to tolerate much warmer living conditions than they do currently. Simultaneously, at the cold-limited boundaries of their present ranges, they would have an opportunity to expand into areas that warmed and thereby invited their colonization. Hence, with stable heat-limited boundaries and poleward- and upward-moving cold-limited boundaries, earth's plants in a CO2-enriched and warmer world would actually experience increases in the sizes of the territories they could successfully inhabit, making them not more likely but less likely to experience extinction.

Either not knowing or refusing to acknowledge these facts, Thomas et al. cited the similar warming-induced extinction papers of Root et al. (2003) and Parmesan and Yohe (2003) as the primary justification for their approach to the issue, apparently oblivious of the fact that the real-world observations contained in the host of studies these authors cited in support of their conclusions actually argue against the validity of their mass extinction claims, as we have demonstrated in exhaustive detail in our Specter of Species Extinction report.

It is likewise ironic that Thomas et al. attempted to justify their sweeping conclusions by acknowledging that climate change over the prior thirty years had been implicated in only a single "species-level extinction," citing the study of Pounds et al. (1999) in this regard. If they had read our Specter of Species Extinction report, however, they would have learned that this claim was convincingly refuted by Lawton et al. (2001), who demonstrated that the cause of the putative extinction was not an increase in temperature brought on by increasing anthropogenic CO2 emissions, but rather a local upwind deforestation of adjacent lowlands that led to increased convective and orographic cloud bases that resulted in a reduced supply of moisture to the habitat area studied by Pounds et al.

In further challenging the contentions of Thomas et al. and their predecessors, Idso et al. (2003) noted that with stable heat-limited boundaries and poleward- and upward-moving cold-limited boundaries, there would be more overlapping of species ranges in a CO2-enriched and warmer world, which would produce significant increases in local biodiversity. What is more, we demonstrated in our report, using the very same studies said by Root et al. (2003) and Parmesan and Yohe (2003) to imply the opposite, that what our analysis suggested had indeed been observed to be the case in many real-world species surveys of both plants and animals, several of the scientific reports of which ironically included Thomas himself as an author!

A totally different analysis of the technique employed by Thomas et al. was provided by Stockwell (2004), who noted that their approach to the issue "ignores species that are currently threatened with extinction by non-climatic factors, and which could therefore benefit from an expanded potential habitat and so escape extinction in the new CO2/climate regime." For example, Stockwell noted that "a CO2- or climate-driven range expansion would clearly help species that are threatened with extinction due to increasing habitat loss attributable to expanding urbanization and agricultural activities; while it may help other species that are threatened with extinction by habitat fragmentation to cross geographical barriers that were previously insurmountable obstacles to them." Consequently, as he continued, "by neglecting the many species that fall into these and other like categories, no decrease in extinctions is possible under Thomas et al.'s approach to the problem, even under [a] free dispersal scenario, with the result that a massive increase in extinctions is a foregone conclusion."

Stockwell further noted that "the no dispersal scenario also forces an unrealistic decrease in range with any climatic change that shifts habitat area without reducing it; while 'overfitting' reduces ranges even more, producing systematic errors on the order of 10-20%, particularly with smaller data sets, deficiencies in data sampling and modeling methods, and the inclusion of irrelevant variables (Stockwell and Peterson 2002a, 2002b, 2003)." In the study of Bakkenes et al. (2002), for example, Stockwell indicated that "two independent climate variables adequately explain 93% of the variation in their dependent variable; while the use of more climate variables ends up incorporating more random variation than it does actual signal, leading to a contraction of the climate envelope and a systematic bias towards smaller predicted ranges." It should come as no surprise, therefore, as Stockwell continued, "that in this study and that of Peterson et al. (2002) -- which comprise two of the six major studies on which the analysis of Thomas et al. is based -- the use of only two climate variables by the two studies yields extinction percentages of 7% and 9%, while the four additional studies upon which Thomas et al. rely (which use from 3 to 36 independent variables) yield extinction percentages ranging from 20% to 34%, consistent with what would be expected from errors associated with statistical overfitting."

Because ecological models are notoriously unreliable, the common-sense response, when extreme results such as those of Thomas et al. are encountered, would be to attempt to verify some aspect of them with independent data. However, in the words of Stockwell, "their single attempt to do so with a real-world extinction supposedly caused by global warming (Pounds et al., 1999) has been satisfactorily explained by changes in local weather patterns due to upwind deforestation of adjacent lowlands (Lawton et al., 2001)." Hence, Stockwell rightly concluded that "Thomas et al. have a dearth of pertinent hard data to support their contentions; and while the absence of evidence does not necessarily disprove a claim, the lack of any real extinction data to support the results of their analysis certainly suggests that the models they are using are not 'tried and true'."

Stockwell's final thoughts on the matter, therefore, were that "Thomas et al. (2004) seek to create the impression of impending ecological disaster due to CO2-induced global warming, claiming their results justify mandating reductions of greenhouse gas emissions," but he states that their findings "are forced by the calculations, confounded with statistical bias, lack supporting real-world evidence, and are perforated with speculation," concluding that "their doctrine of 'massive extinction' is actually a case of 'massive extinction bias'."

Two years later, Parmesan (2006) published a review of 866 papers that addressed the subject of ecological and evolutionary responses to the global warming of the prior few decades, wherein new concerns had been raised about the ability of earth's many species of plants and animals to maintain a viable foothold on the planet if temperatures were to continue to rise. However, much of the evidence cited by Parmesan actually weighed heavily against this concern.

For starters, Parmesan noted that "most observations of climate-change responses have involved alterations of species' phenologies." She reported, for example, that many species had exhibited "advancement of spring events," such that there had been "a lengthening of vegetative growing season in the Northern Hemisphere," which is something most people would consider a positive phenomenon. She also reported that "summer photosynthetic activity increased from 1981-1991" -- another positive response -- and that the growing season throughout the United States "was unusually long during the warm period of the 1940s," but that "since 1996, growing season length has increased only in four of the coldest, most-northerly zones (42°-45° N latitude), not in the three warmest zones (32°-37° N latitude)," which makes one wonder if it was not warmer throughout most of the United States in the 1940s than it was at the end of the 20th century.

The negativity that Parmesan associated with these mostly-positive warming-induced phenological changes arises from the possibility that there may be "mismatches" across different trophic levels in natural ecosystems, such as between the time that each year's new crop of herbivores appears and the time of appearance of the plants they depend upon for food. Eleven plant-animal associations had been intensively studied in this regard; and in seven of them Parmesan said "they are more out of synchrony now than at the start of the studies."

It must be noted, however, that there will always be winners and losers (some big and some small) in such animal-plant matchups during periods of climate change, and maybe a whole lot of "draws." In addition, it must be emphasized that the current paucity of pertinent data precludes a valid determination of which of the three alternatives is the most likely to predominate. As one example of a "big loser" in the face of recent global warming, Parmesan reported that "field studies have documented that butterfly-host asynchrony has resulted directly in population crashes and extinctions." But population extinctions are not the same as species extinctions; and she acknowledges that the local extinctions to which she referred had merely resulted in "shifting [the] mean location of extant populations northward [in the Northern Hemisphere] and upward."

The second of the major biological responses to global warming addressed by Parmesan was that of species migration, which is often touted as leading to range restrictions that make it difficult for species to maintain the "critical mass" required for their continued existence. For example, it is often claimed that global warming will be so fast and furious that many species will not be able to migrate poleward in latitude or upward in altitude rapidly enough to avoid extinction, or that if located on mountaintops they will actually run out of suitable new habitat to which they can flee when faced with rising temperatures. In this respect, Parmesan essentially rehashed the earlier findings of the meta-analyses of Root et al. (2003) and Parmesan and Yohe (2003), which predominantly portrayed species ranges as expanding in the face of rising temperatures, since warming provides a huge opportunity for species to expand their ranges at their cold-limited boundaries while often providing a much reduced impetus for them to retreat at the heat-limited boundaries of their ranges. An example of this phenomenon that was cited by Parmesan occurred in the Netherlands between 1979 and 2001, where she reported that "77 new epiphytic lichens colonized from the south, nearly doubling the total number of species for that community."

Also on the positive side of things, Parmesan reported that "increasing numbers of researchers use analyses of current intraspecific genetic variation for climate tolerance to argue for a substantive role of evolution in mitigating negative impacts of future climate change," additionally noting that the fossil record contains "a plethora of data indicating local adaptation to climate change at specific sites." In addition, she stated that during earlier periods of dramatic climate change there is evidence that many existing species "appeared to shift their geographical distributions as though tracking the changing climate." Interestingly, in both of these situations the outcomes were clearly positive.

The greatest push by Parmesan for a supremely negative consequence of global warming occurred when she said that "documented rapid loss of habitable climate space makes it no surprise that the first extinctions of entire species attributed to global warming are mountain-restricted species," that "many cloud-forest-dependent amphibians have declined or gone extinct on a mountain in Costa Rica (Pounds et al., 1999, 2005)," and that "among harlequin frogs in Central and South American tropics, an astounding 67% have disappeared over the past 20-30 years," citing Pounds et al. (2006) as authority for this latter contention. In carefully reviewing these claims, however, they appear to be far from conclusive.

In the first place, all of the extinctions and disappearances of the amphibian species to which Parmesan refers appear to have nothing at all to do with "rapid loss of habitable climate space" at the tops of mountains. In fact, as noted by Pounds et al. (2006), the loss of these species "is largest at middle elevations, even though higher-elevation species generally have smaller ranges." In addition, as noted in an earlier review of the subject by Stuart et al. (2004), many of the amphibian species declines "took place in seemingly pristine habitats," which had not been lost to global warming nor even modestly altered. Last of all, the extinctions and species disappearances appear not to be due to rising temperatures per se, but to the fungal disease chytridiomycosis, which is caused by Batrachochytrium dendrobatidis, as noted by both Stuart et al. (2004) and Pounds et al. (2006).

In a final attempt to circumnavigate these several dilemmas, Pounds et al. (2006) strove mightily to implicate global warming as the cause of Batrachochytrium's increased virulence in recent years. So convoluted and tenuous was their reasoning, however, that they repeatedly referred to their view of the subject as being but a hypothesis. In addition, in their paper's Supplementary Information, they said that their goal was merely "to stimulate thought and generate ideas concerning the altitudinal patterns of thermal environments, the recent temperature shifts, and the interactions between Batrachochytrium and its amphibian hosts," with the hope that "future experimental studies should examine these ideas, while also considering the influence of other climatic changes such as shifts in precipitation and humidity." Last of all, and most damaging to their thesis, is the almost unbelievable fact, as reported by Bosch et al. (2006), that "Pounds et al. (2006) did not focus on showing whether the pathogen was present, or causing disease, in the species studied, raising questions as to whether infection by B. dendrobatidis [was] actually involved in the observed species declines."

Clearly, the last word on this subject has yet to be written; but Pounds et al. (2006) nevertheless stated as factual that "with climate change promoting infectious disease and eroding biodiversity, the urgency of reducing greenhouse-gas concentrations is now undeniable," indicating their total unwillingness to even entertain the possibility that a different point of view might have merit. Likewise, Parmesan (2006) stated that "range-restricted species, particularly polar and mountaintop species, show more-severe range contractions than other groups and have been the first groups in which whole species have gone extinct due to recent climate change," in a claim that is patently inconsistent with known facts, as indicated above, and as will be made clear in subsequent sections of this review.

In one final paper devoted to the subject of modeling plant and animal responses to global warming, Dormann (2007) felt it important to "review the main shortcomings of species distribution models and species distribution projections," such as those employed and derived by Thomas et al.; and in doing so, he carefully analyzed three aspects of what he described as "problems associated with species distribution models."

The first of these aspects is general species distribution model issues, under which Dorman listed four major problems. The second is extrapolation issues, under which he listed five major problems; while the third is statistical issues, under which he listed six major problems. And after all of these problems were appropriately analyzed, Dormann concluded that shortcomings associated with climate-alarmist analyses of the present distributions of species "are so numerous and fundamental that common ecological sense should caution us against putting much faith in relying on their findings for further extrapolations," in contrast to what is routinely done in studies such as that of Thomas et al., the latter of whose methods and findings, according to Dormann, "have been challenged for conceptual and statistical reasons" by many other researchers.

Dormann thus concluded that climate-alarmist "projections of species distributions are not merely generating hypotheses to be tested by later data," they are being presented as "predictions of tomorrow's diversity, and policy makers and the public will interpret them as forecasts, similar to forecasts about tomorrow's weather," which he clearly feels is both unwarranted and unwise ... and to which we say Amen!

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