Comparing Model Projections with Observations: Amphibians

From ClimateWiki

Still et al. (1999) and Pounds et al. (1999) published a pair of papers in Nature dealing with the cause of major decreases in frog and toad populations in the highland forests of Monteverde, Costa Rica. Those diebacks—in which 20 of 50 local species totally went extinct locally, or were extirpated—had occurred over the prior two decades, a period described by the IPCC as having experienced unprecedented warming. Holmes (1999), in a popular science article describing the mystery’s putative solution, wrote that the authors of the two reports made “a convincing case blaming global climate change for these ecological events.”

Then, however, came the study of Lawton et al. (2001), which presented “an alternative mechanism—upwind deforestation of lowlands—that may increase convective and orographic cloud bases even more than changes in sea surface temperature do.”

The four scientists began by noting the trade winds that reach the Monteverde cloud-forest ecosystem flow across approximately 100 km of lowlands in the Rio San Juan basin, and that deforestation proceeded rapidly in the Costa Rican part of the basin over the past century. By 1992, only 18 percent of the original lowland forest remained. They noted this conversion of forest to pasture and farmland altered the properties of the air flowing across the landscape. The reduced evapotranspiration that followed deforestation, for example, decreased the moisture content of the air mass, and regional atmospheric model simulations suggested there should be reduced cloud formation and higher cloud bases over such deforested areas, which would cause there to be fewer and higher-based clouds than otherwise would have been the case when the surface-modified air moved into the higher Monteverde region.

At this point there were two competing theories from which to choose a candidate mechanism for the environmental changes that had altered the Monteverde cloud-forest ecosystem: one that was global in nature (CO2-induced warming) and one that was local (upwind lowland deforestation). The matter was resolved by Lawton et al. Noting the lowland forests north of the San Juan River in southeastern Nicaragua had remained largely intact—providing a striking contrast to the mostly deforested lands in neighboring Costa Rica—they used satellite imagery to show “deforested areas of Costa Rica’s Caribbean lowlands remain relatively cloud-free when forested regions have well-developed dry season cumulus cloud fields,” noting further the prominent zone of reduced cumulus cloudiness in Costa Rica “lies directly upwind of the Monteverde tropical montane cloud forest.” Consequently, they demonstrated by direct observation that the effects predicted by the theory they espoused did indeed occur in the real world, alongside a “control” area identical in all respects but for the deforestation that produced the cloud effects.

Two years later, Nair et al. (2003) demonstrated that the reduced evapotranspiration that followed prior and ongoing deforestation upwind of the Monteverde cloud forest decreased the moisture contents of the air masses that ultimately reached the tropical preserve, while regional atmospheric model simulations they conducted indicated there also should have been reduced cloud formation and higher cloud bases over these areas than there were before the deforestation began. Three years after that—in a study that extended the work of Lawton et al. and Nair et al., while exploring in more detail the impact of deforestation in Costa Rican lowland and premontane regions on orographic cloud formation during the dry season month of March—Ray et al. (2006) used the mesoscale numerical model of Colorado State University’s Regional Atmospheric Modeling System to derive high-spatial-resolution simulations “constrained by a variety of ground based and remotely sensed observations,” in order to “examine the sensitivity of orographic cloud formation in the Monteverde region to three different land use scenarios in the adjacent lowland and premontane regions,” namely, “pristine forests, current conditions and future deforestation.”

This observation-constrained modeling work revealed, in the researchers’ words, that historic “deforestation has decreased the cloud forest area covered with fog in the montane regions by around 5–13% and raised the orographic cloud bases by about 25–75 meters in the afternoon.” In addition, they write, their work suggested “further deforestation in the lowland and premontane regions would lead to around [a] 15% decrease in the cloud forest area covered with fog and also raise the orographic cloud base heights by up to 125 meters in the afternoon.” These findings clearly relieved anthropogenic CO2 emissions of blame for the decreases in frog and toad populations that had been experienced in the highland forests of Monteverde, Costa Rica, instead placing that blame squarely on the shoulders of those responsible for the felling of the adjacent lowland forests.

As additional cases of amphibian mass mortality were reported throughout the world, Parmesan (2006) and Pounds et al. (2006) pointed accusing fingers at CO2, this time claiming global warming was promoting the spread of Batrachochytrium dendrobatidis (Bd), a non-hyphal zoosporic fungus that was the immediate cause of the amphibian declines and triggering outbreaks of chytridiomycosis via what came to be known as the climate-linked epidemic hypothesis (CLEH).

Investigating this concept within the Penalara Natural Park in the Sierra de Guadarrama of Central Spain, Bosch et al. (2007) looked for relationships between 20 different meteorological variables and the development of chytridiomycosis infection in the area’s amphibian populations, focusing on “two time periods according to the lack (1976–1996) or presence (1997–2003) of observed chytrid-related mortalities.” This work revealed, as they described it, “a significant association between change in local climatic variables and the occurrence of chytridiomycosis,” leading them to conclude, “rising temperature is linked to the occurrence of chytrid-related disease.”

Being careful not to be too adamant about what their data implied, however, Bosch et al. noted “associations between climate and disease do not necessarily imply causation.” They also stated, “chytrid-related declines are probably the result of a complex web of interaction, and the effects of climate will be conditional on other factors such as host density, amphibian community composition, microbial competitors and zooplankton predators, to name but a few.” To disentangle this network and break it down into its key components, they said it would be necessary “to collect seasonal data on amphibian densities, contemporary and historical measurements of the prevalence and intensity of infection, seasonal mortalities, and fine-scale meteorological conditions from a range of sites that represent altitudinal clines,” and conduct “molecular epidemiological analyses.” Consequently, and in light of the many complexities they listed, it was clear the last word on the subject was yet to be written—and, in fact, several additional studies appeared in print the following year.

Lips et al. (2008) evaluated data pertaining to population declines of frogs of the genus Atelopus, as well as similar data from other amphibian species, in Lower Central America and Andean South America, based on their own work and that of others recorded in the scientific literature. They sought to determine whether the documented population declines were more indicative of an emerging infectious disease or a climate-change-driven infectious disease, noting in this regard, “both field studies on amphibians (Briggs et al., 2005; Lips et al., 2006) and on fungal population genetics (Morehouse et al., 2003; Morgan et al., 2007) strongly suggest that Bd is a newly introduced invasive pathogen.”

In discussing their findings, Lips et al. said they revealed “a classical pattern of disease spread across native populations, at odds with the CLEH proposed by Pounds et al. (2006).” Emphasizing that the latter’s “analyses and re-analyses of data related to the CLEH all fail to support that hypothesis,” Lips et al. went on to conclude their own analyses supported “a hypothesis that Bd is an introduced pathogen that spreads from its point of origin in a pattern typical of many emerging infectious diseases,” reemphasizing that “the available data simply do not support the hypothesis that climate change has driven the spread of Bd in our study area.”

Although the four U.S. scientists made it clear disease dynamics are indeed “affected by micro- and macro-climatic variables,” and “such synergistic effects likely act on Bd and amphibians,” their work clearly showed the simplistic scenario represented by the CLEH—which posits, in their words, that “outbreaks of chytridiomycosis are triggered by a shrinking thermal envelope”—paints an unrealistic picture of the role of global climate change in the much-more-complicated setting of real-world biology, where many additional factors may play even greater roles in determining amphibian well-being.

Laurance (2008) tested the hypothesis, put forward by Pounds et al. (2006), that “the dramatic, fungal pathogen-linked extinctions of numerous harlequin frogs (Atelopus spp.) in upland rainforests of South America mostly occurred immediately following exceptionally warm years, implicating global warming as a likely trigger for these extinctions.” This he did “using temperature data for eastern Australia, where at least 14 upland-rainforest frog species [had] also experienced extinctions or striking population declines attributed to the same fungal pathogen, and where temperatures [had] also risen significantly in recent decades.” This work, in Laurance’s words, provided “little direct support for the warm-year hypothesis of Pounds et al.” Instead, he “found stronger support for a modified version of the warm-year hypothesis,” where frog declines were likely to occur only following three consecutive years of unusually warm weather; and these declines were observed “only at tropical latitudes, where rising minimum temperatures were greatest.”

In further discussing his findings, Laurance stated many researchers “remain unconvinced that ongoing disease-linked amphibian declines are being widely instigated by rising global temperatures or associated climatic variables, as proposed by Pounds et al.” He noted, for example, “chytrid-linked amphibian declines have been documented on several continents and at varying times” and to date, “no single environmental stressor has been identified that can easily account for these numerous population crashes.” He continued, “it stretches plausibility to argue that the chytrid pathogen is simply an opportunistic, endemic microparasite that has suddenly begun causing catastrophic species declines as a consequence of contemporary global warming.”

Rohr et al. (2008) provided a rigorous test of the two competing hypotheses by evaluating “(1) whether cloud cover, temperature convergence, and predicted temperature-dependent Bd growth are significant positive predictors of amphibian extinctions in the genus Atelopus and (2) whether spatial structure in the timing of these extinctions can be detected without making assumptions about the location, timing, or number of Bd emergences.” After completing their research, the five scientists reported “almost all of our findings are contrary to the predictions of the chytrid-thermal-optimum hypothesis,” even noting “not all of the data presented by Pounds et al. (2006) are consistent with the chytrid-thermal-optimum hypothesis.” They note, “there was no regional temperature convergence in the 1980s when extinctions were increasing, and that convergence only occurred in the 1990s when Atelopus spp. extinctions were decreasing, opposite to the conclusions of Pounds et al. (2006) and the chytrid-thermal-optimum hypothesis.” On the other hand, they report, “there is a spatial structure to the timing of Atelopus spp. extinctions but that the cause of this structure remains equivocal, emphasizing the need for further molecular characterization of Bd.”

The next year, Alford et al. (2009)—no longer feeling any need to address the repudiated climate-linked epidemic hypothesis—quantified four movement characteristics of three groups of radio-tracked cane toads (Bufo marinus) at three places in Australia: (1) a location where the toads had been established for some 50 years at the time of their sampling, (2) a location where the first toads arrived about six months before sampling began in 1992 and 1993, and (3) a location where sampling occurred for a period of 13 months, starting at the time of the toads’ initial arrival in 2005. The results of this exercise revealed that for all of the movement parameters they studied, “toads from the current invasion front differed dramatically from animals in the long-established population, while toads from the earlier invasion front were intermediate between these extremes.”

The five researchers report “cane toads are now spreading through tropical Australia about 5-fold faster than in the early years of toad invasion.” As for why this is so, they state “the current invasion-front animals achieved these [high invasion speeds] by rarely reusing the same retreat site two days in succession, by travelling further each night when they did move, and by moving along straighter paths.” Therefore, as they describe it, the toad invasion front “advances much more rapidly than would occur if the toads retained ancestral behaviors (less frequent relocation, with shorter movements, and fewer toads using straight paths).” And because of the fact that “invasion-front toads in 1992 were more dispersive than origin-population toads in the same year, but that invasion-front toads have continued to evolve heightened dispersal ability and dispersed even more effectively in 2005 than they did in 1992,” these observations suggest “as long as toads continue to invade suitable new habitat, dispersal ability will be selected upwards.”

In discussing their findings, Alford et al. write that the rapidity and magnitude of the shifts in cane toads “are truly remarkable,” having been accomplished in only 50 generations (about 70 years), and they state “such a major shift over such a brief period testifies to the intense selective pressure exerted on frontal populations of range-shifting species.” This development, in their words, “not only has implications for our understanding of the rates of invasion by non-native species, but also for the rate of range-shift in native taxa affected by climate change.” The implication to which they refer is that the capacity for species to respond to changing environments may be underestimated when it is based on observations of individuals at the core of their range.

In further exploration of the issue, Bustamante et al. (2010) exposed groups of Panamanian golden frogs (Atelopus zeteki) to varying dosages of zoospores of Batrachochytrium dendrobatidis (Bd) as well as to different temperatures and hydric environments, in order to ascertain whether the frogs were susceptible to the pathogen and, if so, how environmental factors might affect the frogs’ survival. Results of these several operations indicated (1) “frogs exposed to a dosage of 100 Bd zoospores survived significantly longer than those that had been exposed to 104 or 106 zoospores,” (2) “exposed frogs housed at 23°C survived significantly longer than those that were housed at 17°C,” and (3) “exposed frogs held in dry conditions survived significantly longer than those in wet conditions.”

Since their study was conducted in a laboratory, Bustamante et al. acknowledge their results “do not directly test hypotheses about the relation between climate change and the decline of the frogs in the field,” but they note their data nevertheless “do not support the contention that rising global temperatures are necessary to cause the death of amphibians infected with this pathogen, because the pathogen was just as lethal at 17°C as at 23°C, and frogs at the warmer temperature lived significantly longer than those at the cooler one.” This result is inconsistent with the climate-linked epidemic hypothesis of Pounds et al. (2006)—and Bustamante was a coauthor of that paper.

The most recent work to be devoted to the struggles of amphibians comes from Anchukaitis and Evans (2010). They write, “widespread amphibian extinctions in the mountains of the American tropics have been blamed on the interaction of anthropogenic climate change and a lethal pathogen.” In this regard, they note, “limited meteorological records make it difficult to conclude whether current climate conditions at these sites are actually exceptional in the context of natural variability,” questioning once again the original contention that modern global warming was the primary culprit in the demise of the Monteverde golden toad (Bufo periglenes).

In an attempt to shed significant new light on the subject, Anchukaitis and Evans developed annual proxy records of hydroclimatic variability over the past century within the Monteverde Cloud Forest of Costa Rica, based on measurements of the stable oxygen isotope ratio (δ18O) made on trees lacking annual rings, as described in the papers of Evans and Schrag (2004) and Anchukaitis et al. (2008). That work revealed, in the words of the two researchers, that “contrary to interpretations of the short instrumental record (Pounds et al., 1999), no long-term trend in dry season hydroclimatology can be inferred from our δ18O time series at Monteverde (1900–2002).” Instead, they found, “variability at the interannual scale dominates the isotope signal, particularly during the period of increased ENSO variance since the late 1960s,” and they add, in this regard, “there is no evidence of a trend associated with global warming.” They emphasize “the extinction of the Monteverde golden toad appears to have coincided with an exceptionally dry interval caused by the 1986–1987 El Niño event,” which they describe as “one of the longest driest periods in the last 100 years,” based on their δ18O chronology. In addition, they report, there is currently no consensus on how anthropogenic climate change might influence the El Niño Southern Oscillation, while indicating, “ENSO anomalies in the most recent decades are not beyond the range of natural variability during the instrumental period (Rajagopalan et al., 1997).”

In conclusion, Anchukaitis and Evans state their analysis suggests “the cause of the specific and well-documented extinction of the Monteverde golden toad was the combination of the abnormally strong ENSO-forced dryness and the lethality of the introduced chytrid fungus, but was not directly mediated by anthropogenic temperature trends, a finding from paleoclimatology that is in agreement with statistical reanalysis (Rohr et al., 2008; Lips et al., 2008) of the ‘climate-linked epidemic hypothesis’.” The latter two analyses also had revealed the chytrid-thermal-optimum hypothesis, as it alternatively has been described, to be devoid of merit. Consequently, even in the case of struggling amphibians, there are no real-world data that provide any support for the contention that global warming is, or ever will be, responsible for driving them to extinction. In fact, there are examples of just the opposite occurring.

Writing that “phenotypic plasticity, the capacity of a genotype to produce distinct phenotypes under different environmental conditions, is a common and powerful method of adaptation in nature,” Orizaola and Laurila (2009) investigated variations in temperature-induced plasticity in larval life-history traits among populations of an isolated metapopulation of pool frogs (Rana lessonae) in Central Sweden. This they did by exposing larvae from three closely located populations to two temperatures (20 and 25°C) in the laboratory and then documenting their growth and development responses at the two different temperatures. According to the two Swedish researchers, the results of their experiment indicated (1) “in general, larvae exposed to warmer temperature experienced higher survival and metamorphosed faster,” (2) there “were differences among the populations in both trait mean values and in the plastic responses,” and (3) “among-family variation within populations was found in growth rate and time to metamorphosis, as well as in plasticity suggesting that these traits have a capacity to evolve.”

Based on these observations, Orizaola and Laurila found “strong population differentiation at a microgeographic scale in life-history characteristics and temperature-induced plasticity in [the] isolated amphibian metapopulation,” and that in spite of “the near absence of molecular genetic variation within [the] metapopulation, [their] study detected strong variation in trait means and plastic responses both among and within populations, possibly suggesting that natural selection is shaping life-history traits of the local populations,” which phenomenon may be preparing them for still further temperature increases by providing them “ample phenotypic variation” to deal with a potentially warming environment.

In additional studies showing real-world data refute the contention that global warming is driving amphibians to extinction, Berger et al. (2004) found lower temperatures enhanced the development of chytridiomycosis in a study of eastern Australian frogs, while Seimon et al. (2007) determined glacial recession in the Peruvian Andes has been creating new amphibian habitats at recently deglaciated sites. McCaffery and Maxell (2010) documented an increase in survival and breeding probability in the Columbia spotted frog of the Bitterroot Mountains of Montana (USA) as the severity of winter decreased, leading them to conclude “a warming climate with less severe winters is likely to promote population viability in this montane frog population.”

Woodhams et al. (2010) recently noted “amphibian skin peptides are one important defense against chytridiomycosis,” while examining “the population-level variation in this innate immune defense to understand its relationship with disease dynamics.” Briggs et al. (2010) have noted some amphibians with chytridiomycosis “develop only minor infections and suffer little or no negative effects.” And Zukerman (2010) reports some of the most devastated populations of Australia's barred river frogs (Mixophyes esiteratus), tusked-frogs (Adelotus sp.), and several tree frog species (Litoria sp.), once thought to have been wiped out by the fungus, are now showing strong signs of recovery.

References

Alford, R.A., Brown, G.P., Schwarzkopf, L, Phillips, B.L., and Shine, R. 2009. Comparisons through time and space suggest rapid evolution of dispersal behavior in an invasive species. Wildlife Research 36: 23–28.

Anchukaitis, K.J. and Evans, M.N. 2010. Tropical cloud forest climate variability and the demise of the Monteverde golden toad. Proceedings of the National Academy of Sciences, USA 107: 5036–5040.

Anchukaitis, K.J., Evans, M.N., Wheelwright, N.T., and Schrag, D.P. 2008. Stable isotope chronology and climate signal in neotropical montane cloud forest trees. Journal of Geophysical Research 113: G03030.

Berger, L, Speare, R, Hines, H.B., Marantelli, G., Hyatt, A.D., McDonald, K.R., Skerratt, L.F., Olsen, V., Clarke, J.M., Gillespie, G., Mahony, M., Sheppard, N., Williams, C., and Tyler, M.J. 2004. Effect of season and temperature on mortality in amphibians due to chytridiomycosis. Australian Veterinary Journal 82: 432–439.

Bosch, J., Carrascal, L.M., Duran, L., Walker, S., and Fisher, M.C. 2007. Climate change and outbreaks of amphibian chytridiomycosis in a montane area of Central Spain: Is there a link? Proceedings of the Royal Society B 274: 253–260.

Briggs, C.J., Knapp, R.A., and Vredenburg, V.T. 2010. Enzootic and epizootic dynamics of the chytrid fungal pathogen of amphibians. Proceedings of the National Academy of Sciences, USA 107: 9695–9700.

Briggs, C.J., Vredenburg, V., Knapp, R.A., and Rachowicz, L.J. 2005. Investigating the population-level effects of chytridiomycosis, an emerging infectious disease of amphibians. Ecology 86: 3149–3159.

Bustamante, H.M., Livo, L.J., and Carey, C. 2010. Effects of temperature and hydric environment on survival of the Panamanian Golden Frog infected with a pathogenic chytrid fungus. Integrative Zoology 5: 143–153.

Evans, M.N. and Schrag, D.P. 2004. A stable isotope-based approach to tropical dendroclimatology. Geochimica et Cosmochimica Acta 68: 3295–3305.

Holmes, R. 1999. Heads in the clouds. New Scientist (8 May): 32–36.

Laurance, W.F. 2008. Global warming and amphibian extinctions in eastern Australia. Austral Ecology 33: 1–9.

Lawton, R.O., Nair, U.S., Pielke Sr., R.A., and Welch, R.M. 2001. Climatic impact of tropical lowland deforestation on nearby montane cloud forests. Science 294: 584–587.

Lips, K.R., Brem, F., Brenes, R., Reeve, J.D., Alford, R.A., Voyles, J., Carey, C., Livo, L., Pessier, A.P., and Collins, J.P. 2006. Emerging infectious disease and the loss of biodiversity in a Neotropical amphibian community. Proceedings of the National Academy of Sciences USA 103: 3165–3170.

Lips, K.R., Diffendorfer, J., Mendelson III, J.R., and Sears, M.W. 2008. Riding the wave: reconciling the roles of disease and climate change in amphibian declines. PLoS (Public Library of Science) Biology 6(3): e72. doi:10.1371/journal.pbio.0060072.

McCaffery, R.M. and Maxell, B.A. 2010. Decreased winter severity increases viability of a montane frog population. Proceedings of the National Academy of Sciences, USA 107: 8644–8649.

Morehouse, E.A., James, T.Y., Ganley, A.R.D., Vilgalys, R., Berger, L., Murphy, P.J., and Longcore, J.E. 2003. Multilocus sequence typing suggests the chytrid pathogen of amphibians is a recently emerged clone. Molecular Ecology 12: 395–403.

Morgan, J.A.T., Vredenburg, V., Rachowicz, L.J., Knapp, R.A., Stice, M.J., Tunstall, T., Bingham, R.E., Parker, J.M., Longcore, J.E., Moritz, C., Briggs, C.J., and Taylor, J.W. 2007. Enigmatic amphibian declines and emerging infectious disease: population genetics of the frog-killing fungus Batrachochytrium dendrobatidis. Proceedings of the National Academy of Sciences USA 104: 13,845–13,850.

Nair, U.S., Lawton, R.O., Welch, R.M., and Pielke Sr., R.A. 2003. Impact of land use on Costa Rican tropical montane cloud forests: sensitivity of cumulus cloud field characteristics to lowland deforestation. Journal of Geophysical Research 108: 10.1029/2001JD001135.

Orizaola, G. and Laurila, A. 2009. Microgeographic variation in temperature-induced plasticity in an isolated amphibian metapopulation. Evolutionary Ecology 23: 979–991.

Parmesan, C. 2006. Ecological and evolutionary responses to recent climate change. Annual Review of Ecology, Evolution, and Systematics 37: 637–669.

Pounds, J.A., Bustamante, M.R., Coloma, L.A., Consuegra, J.A., Fogden, M.P.L., Foster, P.N., La Marca, E., Masters, K.L., Merino-Viteri, A., Puschendorf, R., Ron, S.R., Sanchez-Azofeifa, G.A., Still, C.J., and Young, B.E. 2006. Widespread amphibian extinctions from epidemic disease driven by global warming. Nature 439: 161–167.

Pounds, J.A., Fogden, M.P.L., and Campbell, J.H. 1999. Biological response to climate change on a tropical mountain. Nature 398: 611–615.

Rajagopalan, B., Lall, U., and Cane, M.A. 1997. Anomalous ENSO occurrences: An alternate view. Journal of Climate 10: 2351–2357.

Ray, D.K., Nair, U.S., Lawton, R.O., Welch, R.M., and Pielke Sr., R.A. 2006. Impact of land use on Costa Rican tropical montane cloud forests: Sensitivity of orographic cloud formation to deforestation in the plains. Journal of Geophysical Research 111: 10.1029/2005JD006096.

Rohr, J.R., Raffel, T.R., Romansic, J.M., McCallum, H., and Hudson, P.J. 2008. Evaluating the links between climate, disease spread, and amphibian declines. Proceedings of the National Academy of Sciences USA 105: 17,436–17,441.

Seimon, T.A., Seimon, A., Daszak, P., Halloy, S.R.P., Schloegel, L.M., Aguilar, C.A., Sowell, P., Hyatt, A.D., Konecky, B., and Simmons, J.E. 2007. Upward range extension of Andean anurans and chytridiomycosis to extreme elevations in response to tropical deglaciation. Global Change Biology 13: 288–299.

Still, C.J., Foster, P.N., and Schneider, S.H. 1999. Simulating the effects of climate change on tropical montane cloud forests. Nature 398: 608–610.

Woodhams, D.C., Kenyon, N., Bell, S.C., Alford, R.A., Chen, S., Billheimer, D., Shyr, Y., and Rollins-Smith, L.A. 2010. Adaptations of skin peptide defenses and possible response to the amphibian chytrid fungus in populations of Australian green-eyed treefrogs, Litoria genimaculata. Diversity and Distributions 16: 703–712.

Zukerman, W. 2010. Fungus out! The frog resistance is here. NewScientist 2790 (10 December) http://www.newscientist.com/article/mg20827903.500-fungus-out-the-frog-resistance-is-here.html.

Comparing Model Projections with Observations: Amphibians

From ClimateWiki

References

Related Links

Views

Personal tools

Navigation

Search

Toolbox