How does rising atmospheric CO2 affect marine organisms?

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Global Warming and Ecosystem Species Richness
Volume 12, Number 12: 25 March 2009

Climate alarmists have long contended that global warming will be so fast and furious that many species of plants will not be able to migrate poleward in latitude or upward in altitude at rates required to keep them within the geographically-shifting temperature regimes to which they have long been adapted, with the result that (1) many species will be driven to extinction and (2) the species richness of various ecosystems will be greatly reduced.

As some examples of these contentions, Dyer (1995) wrote that "the magnitude of the projected warming is considerable," that "the rate at which it is predicted to occur is unprecedented," and that consequently, "there is genuine reason for concern that the extent of range shifts will exceed the dispersal abilities of many plant species." Four years later, Malcolm and Markham (2000) similarly wrote that "rapid rates of global warming are likely to increase rates of habitat loss and species extinction," and that "many species may be unable to shift their ranges fast enough to keep up with global warming." Malcolm et al. (2002) added that "migration rates required by the warming are unprecedented by historical standards, raising the possibility of extensive, and in many cases, catastrophic, species loss." And in his 26 April 2007 testimony to the Select Committee of Energy Independence and Global Warming of the United States House of Representatives, NASA's James Hansen stated that "greenhouse gas emissions threaten many ecosystems," contending that "very little additional forcing is needed ... to cause the extermination of a large fraction of plant and animal species," since "polar species can be pushed off the planet, as they have no place else to go," and stating that "life in alpine regions ... is similarly in danger of being pushed off the planet."

So what's the latest word on the subject from scientists who are actually observing the real world to see how earth's plants have responded to what climate alarmists routinely describe as the unprecedented warming of the past few decades?

An enlightening reality check is provided by Le Roux and McGeoch (2008), who examined patterns of altitudinal range changes in the totality of the native vascular flora of sub-Antarctic Marion Island (4654'S, 3745'E) in the southern Indian Ocean, which warmed by 1.2C 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 elevational boundaries by an average of 70 meters. And because, as they describe it, "the observed upslope expansion was not matched by a similar change in lower range boundaries," they emphasize the fact that "the flora of Marion Island has undergone range expansion rather than a range shift [our italics]." In addition, they appropriately note 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, the theoretical basis for which outcome we have described in our special report The Specter of Species Extinction. And as a further consequence of this fact, le Roux and McGeoch indicate 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 that of the recent past.

Sherwood, Keith and Craig Idso

References
Dyer, J.M. 1995. Assessment of climatic warming using a model of forest species migration. Ecological Modelling 79: 199-219.

Le Roux, P.C. and McGeoch, M.A. 2008. Rapid range expansion and community reorganization in response to warming. Global Change Biology 14: 2950-2962.

Malcolm, J.R., Liu, C., Miller, L.B., Allnutt, T. and Hansen, L. 2002. Habitats at Risk: Global Warming and Species Loss in Globally Significant Terrestrial Ecosystems. World Wide Fund for Nature, Gland, Switzerland.

Malcolm, J.R. and Markham, A. 2000. Global Warming and Terrestrial Biodiversity Decline. World Wide Fund for Nature, Gland, Switzerland.