Learn how plants respond to higher atmospheric CO2 concentrations

How does rising atmospheric CO2 affect marine organisms?

Click to locate material archived on our website by topic


Carbon Dioxide and Earth's Future: Pursuing the Prudent Path

7. Widespread Plant and Animal Extinctions


The claim: With respect to plants and animals, global warming alarmists have long contended that the increase in temperature predicted to result from the ongoing rise in the atmosphere's CO2 concentration will be so great and occur so fast that many species of plants and animals will not be able to migrate poleward in latitude or upward in elevation rapidly enough to avoid extinction.

In his 26 April 2007 testimony to the Select Committee of Energy Independence and Global Warming of the U.S. House of Representatives, entitled "Dangerous Human-Made Interference with Climate," NASA's chief climate alarmist -- James Hansen -- declared that "continued business-as-usual greenhouse gas emissions threaten many ecosystems," as he contended that "very little additional forcing is needed ... to cause the extermination of a large fraction of plant and animal species," while stating that in response to global warming, "polar species can be pushed off the planet, as they have no place else to go," and claiming that "life in alpine regions ... is similarly in danger of being pushed off the planet." So what's the real story?

We have already indicated, in earlier sections of this document, that anthropogenic CO2 emissions cannot have been responsible for the 20th-century recovery of the earth from the global chill of the Little Ice Age, and that that warming -- due to whatever phenomenon may have caused it -- has not led to catastrophic increases in extreme floods, droughts and hurricanes, nor to increases in heat-induced human mortality and viral diseases. In what follows, therefore, we focus on the biosphere or the world of nature, investigating the climate-alarmist claim that the warming predicted by current state-of-the-art climate models will drive numerous species of plants and animals to oblivion, consigning them to a vicarious existence that manifests itself only in history books.

With respect to plants and their amazing resilience, we begin with the study of Holzinger et al. (2008), who revisited areas of twelve mountains having summits located between elevations of 2844 and 3006 meters in the canton of Grisons, Switzerland, where in 2004 they assembled complete inventories of vascular plant species that they compared with similar inventories made by other researchers in 1885, 1898, 1912, 1913 and 1958, following the ascension paths of the earlier investigators "as accurately as possible," where mean summer temperature increased by at least 0.6°C between the time of the first study and their most recent one. This effort revealed upward migration rates on the order of several meters per decade; and the data suggested that vascular plant species richness had increased, and by 11% per decade, over the last 120 years on the mountain summits (defined as the upper 15 meters of the mountains) in the alpine-nival ecotone, where not a single species had been "pushed off the planet." What is more, this finding, in the words of the four researchers, "agrees well with other investigations from the Alps, where similar changes have been detected (Grabherr et al., 1994; Pauli et al., 2001; Camenisch, 2002; Walther, 2003; Walther et al., 2005)."

Contemporaneously, Kelly and Goulden (2008) compared two vegetation surveys (one made in 1977 and the other in 2006-2007) of the Deep Canyon Transect in Southern California's Santa Rosa Mountains, which spans several plant communities and climates, rising from an elevation of 244 meters to 2560 meters over a distance of 16 km, while "climbing through desert scrub, pinyon-juniper woodland, chaparral shrubland, and conifer forest." This work revealed that "the average elevation of the dominant plant species rose by ~65 meters," when the 30-year mean temperature measured at seven stations around Deep Canyon rose by 0.41°C between 1947-1976 and 1977-2006, and when the same metric rose by 0.63°C in the climate regions straddled by the transect, and by 0.77°C at the two weather stations nearest Deep Canyon. In commenting on their observations, the two researchers said they implied that "surprisingly rapid shifts in the distribution of plants can be expected with climate change," and it should be noted that those rapid shifts appear to be fully capable of coping with even the supposedly unprecedented rate of warming climate alarmists have long claimed was characteristic of the last decades of the 20th century.

Also publishing in the same year, Le Roux and McGeoch (2008) examined patterns of altitudinal range changes in the totality of the native vascular flora of sub-Antarctic Marion Island (46°54'S, 37°45'E) in the southern Indian Ocean, which warmed by 1.2°C between 1965 and 2003. The work of these South African researchers revealed that between 1966 and 2006, there was "a rapid expansion in altitudinal range," with species expanding their upper-elevation boundaries by an average of 70 meters. And because, as they described it, "the observed upslope expansion was not matched by a similar change in lower range boundaries," they emphasized the fact that "the flora of Marion Island has undergone range expansion rather than a range shift." In addition, they appropriately noted that "the expansion of species distributions along their cooler boundaries in response to rising temperatures appears to be a consistent biological consequence of recent climate warming," citing references to several other studies that have observed the same type of response.

Another consequence of the stability of lower range boundaries together with expanding upper range boundaries is that there is now a greater overlapping of ranges, resulting in greater local species richness or biodiversity everywhere up and down various altitudinal transects of the island. And as a further consequence of this fact, le Roux and McGeoch indicated that "the present species composition of communities at higher altitudes is not an analogue of past community composition at lower altitudes, but rather constitutes a historically unique combination of species," or what we could truly call a "brave new world," which is significantly richer than the one of the recent past.

One year later, Randin et al. (2009) wrote that "the mean temperature interpolated from local stations at a 20-meter resolution contains more variability than expressed by the mean temperature within a 50-km x 50-km grid cell in which variation in elevation is poorly represented." Or as they described it in another part of their paper, "climatic differences along elevation gradients, as apparent at 25-m x 25-m resolution, allow plant species to find suitable climatic conditions at higher elevation under climate change," whereas "models at a 10 x 10' resolution [10 minutes of latitude x ten minutes of longitude, which correspond to 16-km x 16-km cells in the Swiss Alps, where they carried out their analyses] reflect the mean climatic conditions within the cell, and thus provide imprecise values of the probability of occurrence of species along a thermal gradient."

In testing this "local high-elevation habitat persistence hypothesis," as they described it, the group of Swiss, French and Danish researchers assessed "whether climate change-induced habitat losses predicted at the European scale (10 x 10' grid cells) are also predicted from local-scale data and modeling (25-m x 25-m grid cells)." And in doing so, they found that for 78 mountain species modeled at both European and local scales, the "local-scale models predict persistence of suitable habitats in up to 100% of species that were predicted by a European-scale model to lose all their suitable habitats in the area."

In discussing their findings, Randin et al. suggested that the vastly different results they obtained when using fine and coarse grid scales might help to explain what they call the Quaternary Conundrum, i.e. "why fewer species than expected went extinct during glacial periods when models predict so many extinctions with similar amplitude of climate change (Botkin et al., 2007)." In addition, they noted that "coarse-resolution predictions based on species distribution models are commonly used in the preparation of reports by the Intergovernmental Panel on Climate Change," which are then used by "conservation planners, managers, and other decision makers to anticipate biodiversity losses in alpine and other systems across local, regional, and larger scales," but which, unfortunately, give a highly-warped and erroneous view of the subject.

Moving one year closer to the present, Erschbamer et al. (2009) documented and analyzed changes (from 2001 to 2006) in plant species number, frequency and composition along an altitudinal gradient crossing four summits from the treeline ecotone to the subnival zone in the South Alps (Dolomites, Italy), where minimum temperatures increased by 1.1-2.0°C during the past century with a marked rise over the last decades. In describing their findings, the four researchers stated that "after five years, a re-visitation of the summit areas revealed a considerable increase of species richness at the upper alpine and subnival zone (10% and 9%, respectively) and relatively modest increases at the lower alpine zone and the treeline ecotone (3% and 1%, respectively)." In addition, with respect to threats of extinction, they reported that "during the last five years, the endemic species of the research area were hardly affected," while "at the highest summit, one endemic species was even among the newcomers."

The Austrian scientists thus concluded that "at least in short to medium time scales, the southern alpine endemics of the study area should not be seriously endangered." Moreover, they indicated that "the three higher summits of the study area have a pronounced relief providing potential surrogate habitats for these species." And they also reported that "recently published monitoring data from high altitudes indicate a consistent increase of species richness in the Alps," citing the work of Pauli et al. (2007) and Holzinger et al. (2008).

Working contemporaneously in the nearby Swiss Alps, Stocklin et al. (2009) studied the consequences of the highly structured alpine landscape for evolutionary processes in four different plants (Epilobium fleischeri, Geum reptans, Campanula thyrsoides and Poa alpina), testing for whether genetic diversity within their populations was related to altitude and land use, while seeking to determine whether genetic differentiation among populations was more related to different land use or to geographic distances. Their efforts indicated that within-population genetic diversity of the four species was high and mostly not related to altitude and population size; and they determined that genetic differentiation among populations was pronounced and strongly increasing with distance, implying "considerable genetic drift among populations of alpine plants."

Based on these findings, as well as the observations of others, Stocklin et al. remarked that "phenotypic plasticity is particularly pronounced in alpine plants," and that "because of the high heterogeneity of the alpine landscape, the pronounced capacity of a single genotype to exhibit variable phenotypes is a clear advantage for the persistence and survival of alpine plants." Hence, they concluded that "the evolutionary potential to respond to global change is mostly intact in alpine plants, even at high altitude." And this result makes it much easier to understand why -- even in the face of significant 20th-century global warming -- there have been no species of plants that have been observed to have been pushed off the planet in alpine regions, as has also been demonstrated to be the case by Walther et al. (2005), Kullman (2007), Holzinger et al. (2008), Randin et al. (2009) and Erschbamer et al. (2009).

In a somewhat different type of study, De Frenne et al. (2010) collected seeds of Anemone nemorosa L. (a model species for slow-colonizing herbaceous forest plants) that they found growing along a 2400-km latitudinal gradient stretching from northern France to northern Sweden during three separate growing seasons (2005, 2006 and 2008), after which they conducted sowing trials in incubators, a greenhouse, and under field conditions in a forest, where they measured the effects of different temperature treatments (Growing Degree Hours or GDH) on various seed and seedling traits. In completing these several experiments, the nineteen researchers discovered that "seed mass, germination percentage, germinable seed output and seedling mass all showed a positive response to increased GDH experienced by the parent plant," and that seed and seedling mass increased by 9.7% and 10.4%, respectively, for every 1000 °C-hours increase in GDH, which they say is equivalent to a 1°C rise in temperature over a 42-day period.

As a result of their findings, the team of international scientists -- hailing from Belgium, Estonia, France, Germany and Sweden -- concluded that "if climate warms, this will have a pronounced positive impact on the reproduction of A. nemorosa, especially in terms of seed mass, germination percentage and seedling mass," because "if more seeds germinate and resulting seedlings show higher fitness, more individuals may be recruited to the adult stage." In addition, they wrote that since "rhizome growth also is likely to benefit from higher winter temperatures (Philipp and Petersen, 2007), it can be hypothesized that the migration potential of A. nemorosa may increase as the climate in NW-Europe becomes warmer in the coming decades." And, as we suggest, increasing migration potential implies decreasing extinction potential.

With respect to animals facing the challenge of global warming, climate alarmists generally characterize the situation as highly dangerous for them, just as they do for plants, suggesting that rising temperatures will also drive many of them to extinction. However, and once again as with plants, most research on the subject suggests otherwise.

A good place to begin a review of this subject is a study on butterflies conducted by a group of thirteen researchers in 1999 (Parmesan et al., 1999). These scientists analyzed, over the prior century of global warming, the distributional changes of non-migratory species whose northern boundaries were in northern Europe (52 species) and whose southern boundaries were in southern Europe or northern Africa (40 species). This work revealed that the northern boundaries of the first group shifted northward for 65% of them, remained stable for 34%, and shifted southward for 2%, while the southern boundaries of the second group shifted northward for 22% of them, remained stable for 72%, and shifted southward for 5%, such that "nearly all northward shifts," according to Parmesan et al., "involved extensions at the northern boundary with the southern boundary remaining stable."

This behavior is precisely what we would expect to see if the butterflies were responding to shifts in the ranges of the plants upon which they depend for their sustenance, because increases in atmospheric CO2 concentration tend to ameliorate the effects of heat stress in plants and induce an upward shift in the temperature at which they function optimally. These phenomena tend to cancel the impetus for poleward migration at the warm edge of a plant's territorial range, yet they continue to provide the opportunity for poleward expansion at the cold edge of its range. Hence, it is possible that the observed changes in butterfly ranges over the past century of concomitant warming and rising atmospheric CO2 concentration are related to matching changes in the ranges of the plants upon which they feed. Or, this similarity could be due to some more complex phenomenon, possibly even some direct physiological effect of temperature and atmospheric CO2 concentration on the butterflies themselves. In any event, and in the face of the 0.8°C of "dreaded" global warming that occurred in Europe over the 20th century, the consequences for European butterflies were primarily beneficial, because, as Parmesan et al. described the situation, "most species effectively expanded the size of their range when shifting northwards," since "nearly all northward shifts involved extensions at the northern boundary with the southern boundary remaining stable."

A number of other researchers have also studied the relationship between butterflies and temperature. In the British Isles, Thomas et al. (2001) documented an unusually rapid expansion of the ranges of two butterfly species (the silver-spotted skipper butterfly and the brown argus butterfly) in response to increasing temperatures. In the United States, Crozier (2004) noted that "Atalopedes campestris, the sachem skipper butterfly, expanded its range from northern California into western Oregon in 1967, and into southwestern Washington in 1990," where she reports that temperatures rose by 2-4°C over the prior half-century. And in Canada, White and Kerr (2006) reported butterfly species' range shifts across the country between 1900 and 1990, noting that butterfly species richness increased as "a result of range expansion among the study species" that was "positively correlated with temperature change."

In another intriguing research finding, Gonzalez-Megias et al. (2008) investigated species turnover in 51 butterfly assemblages in Britain by examining regional extinction and colonization events that occurred between the two periods 1976-1982 and 1995-2002, over which time interval the world's climate alarmists claim the planet experienced a warming they contend was unprecedented over the past millennium or more. And in doing so, the five researchers found that regional colonizations exceeded extinctions, as "over twice as many sites gained species as lost species," such that "the average species richness of communities has increased." And they too found that species abundances following colonization likewise increased, due to "climate-related increases in the [land's] carrying capacity."

In comparing their results with those of a broader range of animal studies, Gonzalez-Megias et al. found that "analyses of distribution changes for a wide range of other groups of animals in Britain suggest that southern representatives of most taxa are moving northwards at a rate similar to -- and in some cases faster than -- butterflies (Hickling et al., 2006)," and they report that "as with butterflies, most of these taxonomic groups have fewer northern than southern representatives, so climate-driven colonisations are likely to exceed extinctions." Hence, they suggested that "most of these taxa will also be experiencing slight community-level increases in species richness."

One additional means by which butterflies can cope with high temperatures is through the production of heat-shock proteins (HSPs). According to Karl et al. (2008), HSPs "are thought to play an important ecological and evolutionary role in thermal adaptation," where "the upregulation of stress-inducible HSPs may help organisms to cope with stress thus enhancing survival (Sorensen et al., 2003; Dahlhoff, 2004; Dahlhoff and Rank, 2007)."

Working with Lycaena tityrus, a widespread temperate-zone butterfly that ranges from western Europe to central Asia, Karl et al. tested this hypothesis by comparing expression patterns of stress-inducible HSPs across replicated populations originating from different altitudes, as well as across different ambient temperatures. Their observations revealed a significant interaction between altitude and rearing temperature that indicated that "low-altitude animals showed a strongly increased HSP70 expression at the higher compared with at the lower rearing temperature," which is exactly where one would expect to see such a response in light of its obvious utility.

In discussing their findings, Karl et al. said their observation that "HSP70 expression increased substantially at the higher rearing temperature in low-altitude butterflies ... might represent an adaptation to occasionally occurring heat spells," which further suggests that this response should serve these organisms well in the days and years to come, especially if the dramatic warming and increase in heat spells predicted by the world's climate alarmists ever come to pass, which still further suggests (in light of the similar findings of others) that more of earth's life forms than many have assumed might be genetically equipped to likewise cope with the future thermal dangers envisioned by those enamored with the climate modeling enterprise and its imagined ramifications.

Birds have also been shown to be capable of dealing with increases in temperature. Thomas and Lennon (1999), for example, analyzed the geographical distributions of a number of British bird species over a 20-year period of global warming, looking for climate-induced changes in their breeding ranges between 1970 and 1990. And, as is the case with butterflies, their work revealed that the northern margins of southerly species' breeding ranges shifted northward by an average of 19 km over their study period; while the mean location of the southern margins of northerly species' breeding ranges shifted not at all, which observations are again indicative of expanding ranges and a propensity for birds -- like butterflies -- to become more resistant to extinction in a warming world.

Additional support for this concept was provided by the study of Brommer (2004) of the birds of Finland, which were categorized as either northerly (34 species) or southerly (116 species). In this analysis the researcher quantified changes in their range margins and distributions from two atlases of breeding birds, one covering the period 1974-79 and one covering the period 1986-89, in an attempt to determine how the two groups of species responded to what he called "the period of the earth's most rapid climate warming in the last 10,000 years." Once again, it was determined that the southerly group of bird species experienced a mean poleward advancement of their northern range boundaries of 18.8 km over the 12-year period of supposedly unprecedented warming. The southern range boundaries of the northerly species, on the other hand, were essentially unmoved, leading once again to range expansions that should have rendered the Finnish birds less subject to extinction than they were before the warming.

In an equally revealing study, Maclean et al. (2008) analyzed counts of seven wading bird species -- the Eurasian oystercatcher, grey plover, red knot, dunlin, bar-tailed godwit, Eurasian curlew and common redshank -- made at approximately 3500 different sites in Belgium, Denmark, France, Germany, Ireland, the Netherlands and the United Kingdom on at least an annual basis since the late 1970s. This they did in order to determine what range adjustments the waders may have made in response to concomitant regional warming, calculating the weighted geographical centroids of the bird populations for all sites with complete coverage for every year between 1981 and 2000.

This work revealed, in the words of the seven scientists, that "the weighted geographical centroid of the overwintering population of the majority of species shifted in a northeasterly direction, perpendicular to winter isotherms," with overall 20-year shifts ranging from 30 to 119 km. In addition, they reported that "when the dataset for each species was split into 10 parts, according to the mean temperature of the sites, responses are much stronger at the colder extremities of species ranges." In fact, they found that "at warmer sites, there was no palpable relationship between changes in bird numbers and changes in temperature." Hence, they concluded that "range expansions rather than shifts are occurring" as the planet warms.

In discussing the significance of their findings, the members of the international research team said that the commonly used climate-envelope approach to predicting warming-induced species migrations -- which was the one employed by many climate alarmists -- "essentially assumes that as climate alters, changes at one margin of a species' range are mirrored by those at the other, such that approximately the same 'climate space' is occupied regardless of actual climate," but that their work suggests "that this may not be the case: climate space can also change."

In further discussing their important finding, Maclean et al. wrote that "it is actually not surprising that responses to temperature appear only to be occurring at the colder extremities of species ranges," for they note that "it has long been known that it is common for species to be limited by environmental factors at one extremity, but by biological interactions at the other," citing the work of Connell (1983) and Begon et al. (2005). Thus, they concluded that it is likely that "the warmer extremities of the species ranges examined in this study are controlled primarily by biotic interactions, whereas the colder margins are dependent on temperature."

Similarly, and noting that "climate envelopes (or the climatic niche concept) are the current methods of choice for prediction of species distributions under climate change," Beale et al. (2008) remind us that "climate envelope methods and assumptions have been criticized as ecologically and statistically naive (Pearson and Dawson, 2003; Hampe, 2004)," and that "there are many reasons why species distributions may not match climate, including biotic interactions (Davis et al., 1998), adaptive evolution (Thomas et al., 2001), dispersal limitation (Svenning and Skov, 2007), and historical chance (Cotgreave and Harvey, 1994)." Thus, in an attempt to shed more light on the subject, they evaluated the degree of matchup of species distributions to environment by generating synthetic distributions that retained the spatial structure of observed distributions but were randomly placed with respect to climate. More specifically, "using data on the European distribution of 100 bird species, [they] generated 99 synthetic distribution patterns for each species," and "for each of the 100 species, [they] fitted climate envelope models to both the true distribution and the 99 simulated distributions by using standard climate variables," after which they determined the goodness-of-fit of the many distribution patterns, because, as they describe it, "there has been no attempt to quantify how often high goodness-of-fit scores, and hence ostensibly good matches between distribution and climate, can occur by chance alone."

In a rather surprising result, the three UK researchers determined that "species-climate associations found by climate envelope methods are no better than chance for 68 of 100 European bird species." And, in their words, "because birds are perceived to be equally strongly associated with climate as other species groups and trophic levels (Huntley et al., 2004)," they said that their results "cast doubt on the predictions of climate envelope models for all taxa." And as a result, they concluded that "many, if not most, published climate envelopes may be no better than expected from chance associations alone, questioning the implications of many published studies." The bottom line with respect to our stewardship of the earth is thus well described by their conclusion that "scientific studies and climate change adaptation policies based on the indiscriminate use of climate envelope methods irrespective of species sensitivity to climate may be misleading and in need of revision." And that need for revision is further evidenced by a number of other studies documenting recent range expansions, as opposed to range shifts for bird populations (Thomas and Lennon, 1999; Brommer, 2004; Hitch and Leberg, 2007; Brommer, 2008; Grandegeorge et al., 2008).

In considering the above observations, and when contemplating the special abilities of winged creatures, such as butterflies and birds, it does not appear to be much of a problem for them to compensate for whatever degree of stress a temperature increase might impose upon them by merely moving to more hospitable living quarters, or to actually take advantage of whatever new opportunities global warming might present for them. Furthermore, and aside from range expansions, rising temperatures also appear to be helping birds in other ways.

Thomas et al. (2010), for example, write that "the timing of annual breeding is a crucial determinant of reproductive success, individual fitness, and population performance, particularly in insectivorous passerine birds," because "by synchronizing hatching with the narrow time window of maximal food abundance, parents can enhance their reproductive success through an increase in offspring growth rate and body condition, survival to fledging, and subsequent recruitment into the breeding population." But many people worry, in this regard, that global warming may upset such biological synchronizations, leading to downward trends in the populations of many species of birds and other animals, which is yet another climate-alarmist nightmare. However, as many studies have shown, rising temperatures have actually been documented to benefit bird breeding performance (Halupka et al., 2008; Husek and Adamik, 2008; Monroe et al., 2008; Dyrcz and Halupka, 2009; Thomas et al., 2010) and population size (Julliard et al., 2004; Gregory et al., 2005; Raven et al., 2005; Lemoine et al., 2007; Seoane and Carrascal, 2008).

But what about non-winged animals? Are they capable of adapting to rising temperatures? In a word, yes, as evidenced by the results of the several research studies highlighted below.

Norment et al. (1999) summarized and compared the results of many surveys of mammal populations observed along the Thelon River and its tributaries in the Canadian Northwest Territories from the 1920s through much of the 1990s. Over this time period, red squirrel, moose, porcupine, river otter and beaver were found to have established themselves in the area, significantly increasing its biodiversity. The three researchers stated that these primarily northward range expansions could be explained by either "a recent warming trend at the northern treeline during the 1970s and 1980s" or "increasing populations in more southerly areas." In either case, we have a situation where several types of mammals appear to have fared quite well in the face of increasing temperatures in this forest-tundra landscape.

Chamaille-Jammes et al. (2006) studied four unconnected populations of the common lizard (Lacerta vivipara), a small live-bearing lacertid that lives in peat bogs and heath lands scattered across Europe and Asia, concentrating on a small region near the top of Mont Lozere in southeast France, at the southern limit of the species' range. More specifically, from 1984 to 2001 they monitored a number of life-history traits of the populations, including body size, reproduction characteristics and survival rates, during which time local air temperatures rose by approximately 2.2°C. In doing so, they found that individual body size increased dramatically in all four lizard populations over the 18-year study period, with snout-vent length expanding by roughly 28%. This increase in body size occurred in all age classes and, as they describe it, "appeared related to a concomitant increase in temperature experienced during the first month of life (August)." As a result, they found that "adult female body size increased markedly, and, as fecundity is strongly dependent on female body size, clutch size and total reproductive output also increased." In addition, for a population where capture-recapture data were available, they learned that "adult survival was positively related to May temperature."

In summarizing their findings, the French researchers stated that since all fitness components investigated responded positively to the increase in temperature, "it might be concluded that the common lizard has been advantaged by the shift in temperature." This finding, in their words, stands in stark contrast to the "habitat-based prediction that these populations located close to mountain tops on the southern margin of the species range should be unable to cope with the alteration of their habitat." Hence, they concluded that "to achieve a better prediction of a species persistence, one will probably need to combine both habitat and individual-based approaches," noting, however, that individual responses, such as those documented in their study (which were all positive), represent "the ultimate driver of a species response to climate change."

Out in the watery realm of the world's oceans, Rombouts et al. (2008) developed the first global description of geographical variation in the diversity of marine copepods in relation to ten environmental variables; and in doing so, they found that "ocean temperature was the most important explanatory factor among all environmental variables tested, accounting for 54 percent of the variation in diversity." Hence, it was not surprising, as they described it, that "diversity peaked at subtropical latitudes in the Northern Hemisphere and showed a plateau in the Southern Hemisphere where diversity remained high from the Equator to the beginning of the temperate regions," which pattern, in their words, "is consistent with latitudinal variations found for some other marine taxa, e.g. foraminifera (Rutherford et al., 1999), tintinnids (Dolan et al., 2006) and fish (Worm et al., 2005; Boyce et al., 2008), and also in the terrestrial environment, e.g. aphids, sawflies and birds (Gaston and Blackburn, 2000)."

"Given the strong positive correlation between diversity and temperature," the six scientists went on to say that "local copepod diversity, especially in extra-tropical regions, is likely to increase with climate change as their large-scale distributions respond to climate warming." This state of affairs is much the same as what has typically been found on land for birds, butterflies and several other terrestrial lifeforms, as their ranges expand and overlap in response to global warming. And with more territory thus available to them, their "foothold" on the planet becomes ever stronger, fortifying them against forces (many of them human-induced) that might otherwise lead to their extinction.

Millar and Westfall (2010) studied American pikas: small generalist herbivores that are relatives of rabbits and hares that inhabit patchily-distributed rocky slopes of western North American mountains and are good at tolerating cold. And as a result of that fact, it is not surprising that pikas are widely believed to have a physiological sensitivity to warming, which when "coupled with the geometry of decreasing area at increasing elevation on mountain peaks," in the words of the two scientists, "has raised concern for the future persistence of pikas in the face of climate change." Therefore, they write that the species "has been petitioned under California [USA] state and federal laws for endangered species listing." And in a study designed to investigate the validity of the basis for that classification, Millar and Westfall developed a rapid assessment method for determining pika occurrence and used it "to assess geomorphic affinities of pika habitat, analyze climatic relationships of sites, and evaluate refugium environments for pikas under warming climates," while working over the course of two field seasons in the Sierra Nevada Mountains of California, the southwestern Great Basin of California and Nevada, and the central Great Basin of Nevada, as well as a small area in the central Oregon Cascades.

In reporting their findings, the two U.S. Forest Service researchers state that "whereas concern exists for diminishing range of pikas relative to early surveys, the distribution and extent in our study, pertinent to four subspecies and the Pacific southwest lineage of pikas, resemble the diversity range conditions described in early 20th-century pika records (e.g., Grinnell and Storer, 1924)." In fact, they say that the lowest site at which they detected the current presence of pikas at an elevation of 1827 meters "is below the historic lowest elevation of 2350 m recorded for the subspecies by Grinnell and Storer (1924) in Yosemite National Park; below the low elevation range limit for the White Mountains populations given by Howell (1924) at 2440 m; and below the lowest elevation described for the southern Sierra Nevada populations of 2134 m (Sumner and Dixon, 1953)." In addition, they say that "a similar situation occurred for another lagomorph of concern, pygmy rabbit (Brachylagus idahoensis), where a rapid assessment method revealed much wider distribution than had been implied from historic population databases or resurvey efforts (Himes and Drohan, 2007)."

Millar and Westfall thus conclude that "pika populations in the Sierra Nevada and southwestern Great Basin are thriving, persist in a wide range of thermal environments, and show little evidence of extirpation or decline," which suggests to us that current concerns about the future of American pikas in a warming world may be wildly misplaced. Moreover, the documentation of a similar phenomenon operating among pygmy rabbits suggests that still other animals may also be better able to cope with various aspects of climate change than we have been led to believe possible.

In providing some background for their study of montane rainforest lizards, Bell et al. (2010) write that tropical species have long been considered to be "especially sensitive to climatic fluctuations because their narrow thermal tolerances and elevational ranges can restrict their ability to persist in, or disperse across, alternate habitats," a concept that NASA's James Hansen expressed much more bluntly by declaring on 21 November 2006 -- when accepting the World Wildlife Fund's Duke of Edinburgh Conservation Medal at St. James Palace in London -- that "species living on the biologically diverse slopes leading to mountains will be pushed off the planet" as the planet warms, opining -- as we have already noted he also did before the U.S. House of Representatives -- that there will simply be no place else for them to go.

In an empirical probe into the substance of this concept, Bell et al. compared "responses to historical climate fluctuation in a montane specialist skink, Lampropholis robertsi, and its more broadly distributed congener, L. coggeri, both endemic to rainforests of northeast Australia," by combining "spatial modeling of potential distributions under representative palaeoclimates, multi-locus phylogeography, and analyses of phenotypic variation." This work revealed, in the words of the seven scientists, that "both species exhibit pronounced phylogeographic structuring for mitochondrial and nuclear genes, attesting to low dispersal and high persistence across multiple isolated regions." And speaking more specifically about L. robertsi, they state that their evidence demonstrates "persistence and isolation" of most populations of the montane species "throughout the strong climate oscillations of the late Pleistocene, and likely extending back to the Pliocene."

Noting that many of the isolated refugia they studied "are particularly rich in narrowly endemic species," Bell et al. state that this characteristic has been attributed to "their relative stability during recent episodes of climate change (Williams and Pearson, 1997; Yeates et al., 2002; Graham et al., 2006; VanDerWal et al., 2009)." And they indicate that these observations "support the general hypothesis that isolated tropical montane regions harbor high levels of narrow-range taxa because of their resilience to past climate change," citing the work of Fjeldsa and Lovett (1997) and Jetz et al. (2004). Thus, they write that "at first sight, species such as L. robertsi would seem especially prone to local extinction and loss of considerable genetic diversity with any further warming; yet, these populations and those of other high-montane endemic species (Cophixalus frogs; Hoskin, 2004) have evidently persisted through past warming events." And thus it is likely they will do so again, if similarly stressed in the future, in spite of the overly-confident contentions of James Hansen and company to the contrary.

Last of all (but happening some time ago), Pockley (2001) reported the results of a survey of the plants and animals on Australia's Heard Island, a little piece of real estate located 4,000 kilometers southwest of Perth. Over the prior fifty years this sub-Antarctic island had experienced a local warming of approximately 1°C that had resulted in a modest (12%) retreat of its glaciers; and hence, for the first time in a decade, scientists were attempting to document what this warming and melting had done to the ecology of the island.

Pockley began by stating the scientists' work had unearthed "dramatic evidence of global warming's ecological impact," which obviously consisted of "rapid increases in flora and fauna." He quoted Dana Bergstrom, an ecologist at the University of Queensland in Brisbane, as saying that areas that previously had been poorly vegetated had become "lush with large expanses of plants." And he added that populations of birds, fur seals and insects had also expanded rapidly. One of the real winners in this regard was the king penguin, which, according to Pockley, had "exploded from only three breeding pairs in 1947 to 25,000."

Eric Woehler of Australia's environment department was listed as a source of other equally remarkable information, such as the Heard Island cormorant's comeback from "vulnerable" status to a substantial 1,200 pairs, and fur seals emergence from "near extinction" to a population of 28,000 adults and 1,000 pups.

Yes, the regional warming experienced at Heard Island actually saved these threatened animal populations from the jaws of extinction. So it's time to celebrate! Responsibility clearly cuts both ways; and if emitters of CO2 are being excoriated, and in advance, for presumably promoting future hypothetical extinctions, they should surely be thanked, even in retrospect, for preventing imminent real-world extinctions.

Back to the Table of Contents