How does rising atmospheric CO2 affect marine organisms?

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Range Expansions (Animals - Other) -- Summary
Could global warming decimate earth's biosphere? Climate alarmists have long claimed that the increase in temperature predicted to result from the ongoing rise in the air's CO2 content will be so great and so rapid that many species of plants and animals will not be able to migrate either poleward in latitude or upward in elevation rapidly enough to avoid extinction, as they are forced to seek cooler living conditions. However, as we explain in our major report The Specter of Species Extinction, there are many reasons for rejecting this contention, one of the most powerful being that increases in the air's CO2 content generally enable plants to endure warmer weather, with the result that there is little need for them to shift the heat-limiting warm-temperature boundaries of their ranges as temperatures rise. At the cold-limiting cool-temperature boundaries of their ranges, on the other hand, warming enables plants to push poleward and upward, which results in expansions of their ranges and reductions in their risk of extinction. We have also reported the results of numerous studies of birds and butterflies that suggest they respond in like manner. Thus, we here report what has been learned about a few other animals in this regard.

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 say that the primarily northward range expansions may be explained by "a recent warming trend at the northern treeline during the 1970s and 1980s." Alternatively, they note that the influx of new species may be due to "increasing populations in more southerly areas." In either case, we have a situation where mammals appear to be faring quite well in the face of increasing temperatures in this forest-tundra landscape.

Studying the distributions of rocky intertidal species along the Pacific coast of Chile, Rivadeneira and Fernandez (2005) determined the mid-20th-century southern endpoints of ten species of gastropods and chitons from museum collections and literature reviews, while they determined current endpoints from field sampling conducted between 1998 and 2000. These efforts revealed that "of the 10 species analyzed, six presented significant changes in their southern limit, whereas four species exhibited no significant shifts." In addition, they found that "of the six species showing significant changes, only two expanded their southern limit, while the four remaining species exhibited significant range contractions." That is to say, their southern boundaries moved in a direction just the opposite to how climate alarmists claim they should have moved. The two researchers also found that "the proportion of species showing contraction, expansion or no change did not differ from a chance expectation."

These results of the Chilean marine biologists suggest that the Pacific coast of Chile may well be another of the many parts of the earth that have not experienced significant warming in recent decades. In fact, their analyses of temperature records collected at five coastal stations actually indicate cooling over the last half-century at two of them; and they cite Rosenbluth et al. (1997) as authority for their statement that "a cooling trend of air temperature has been recorded during the last century between 38S and 41S." Finally, they say that "generalizations about poleward shifts in species ranges cannot be made," although many climate alarmists do it with gusto whenever it pleases them.

Hickling et al. (2005) analyzed changes in the northern and southern range boundaries of 37 non-migratory British Odonata (dragonfly and damselfly) species -- four of which have northern ranges, 24 of which have southern ranges, and nine of which are ubiquitous -- between the two 10-year periods 1960-70 and 1985-95, finding that all but two of the 37 species increased the size of their ranges between the two 10-year periods. With respect to this observation, they report that their "findings that species are shifting northwards faster at their northern range margin than at their southern range margin, are consistent with the results of Parmesan et al. (1999)," adding that "this could suggest that species at their southern range margins are less constrained by climate than by other factors." Consequently, rather than leading to range reductions as a prelude to a massive extinction of species, as has been claimed by many of the world's climate alarmists to be lurking just around the corner, so to speak, global warming, if it continues for some time and its elevated warmth is maintained, will in all likelihood lead to most of earth's species expanding their ranges and gaining even stronger footholds on the planet.

Lastly, Dennis and Sparks (2007) analyzed data pertaining to the general abundance of Lepidoptera in Britain over the 89-year period 1864-1952, based on information assembled by Beirne (1955) via his examination of "several thousand papers in entomological journals describing annual abundances of moths and butterflies." In doing so, they determined that "abundances of British Lepidoptera were significantly positively correlated with Central England temperatures in the current year for each month from May to September and November," and that "increased overall abundance in Lepidoptera coincided significantly with increased numbers of migrants," which latter data were derived from the work of Williams (1965). Taken together, these observations indicate that a warming-driven increase in Lepidopteran species and numbers has been going strong in Britain ever since the end of the Little Ice Age.

From these several references, as well as those pertaining to birds and butterflies, it is clear that a diverse assemblage of animals from a wide array of both terrestrial and aquatic habitats have been expanding their ranges throughout the world over the entire course of the past century or more, gaining stronger footholds on their respective parts of the planet, wherever the direct affronts of mankind are not weakening or destroying them or the ecosystems upon which they depend for their sustenance.

Beirne, B.P. 1955. Natural fluctuations in abundance of British Lepidoptera. Entomologist's Gazette 6: 21-52.

Dennis, R.L.H. and Sparks, T.H. 2007. Climate signals are reflected in an 89 year series of British Lepidoptera records. European Journal of Entomology 104: 763-767.

Hickling, R., Roy, D.B., Hill, J.K. and Thomas, C.D. 2005. A northward shift of range margins in British Odonata. Global Change Biology 11: 502-506.

Norment, C.J., Hall, A. and Hendricks, P. 1999. Important bird and mammal records in the Thelon River Valley, Northwest Territories: Range expansions and possible causes. The Canadian Field-Naturalist 113: 375-385.

Parmesan, C., Ryrholm, N., Stefanescu, C., Hill, J.K., Thomas, C.D., Descimon, H., Huntley, B., Kaila, L., Kullberg, J., Tammaru, T., Tennent, W.J., Thomas, J.A. and Warren, M. 1999. Poleward shifts in geographical ranges of butterfly species associated with regional warming. Nature 399: 579-583.

Rivadeneira, M.M. and Fernandez, M. 2005. Shifts in southern endpoints of distribution in rocky intertidal species along the south-eastern Pacific coast. Journal of Biogeography 32: 203-209.

Rosenbluth, B., Fuenzalida, H.A. and Aceituno, P. 1997. Recent temperature variations in southern South America. International Journal of Climatology 17: 76-85.

Williams, C.B. 1965. Insect Migration. Collins, London, UK, 237 pp.

Last updated 22 July 2009