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Regional Biodiversity in a Warmer World
Volume 11, Number 41: 8 October 2008

NASA's James Hansen claims that as temperatures around the world continue to rise, "polar species can be pushed off the planet, as they have no place else to go," and that life in alpine regions "is similarly in danger of being pushed off the planet," while England's Sir John Houghton declares that "we are in danger of losing thousands, if not millions, of species because of climate change."

These ominous words of warning, which portend significantly reduced species richness over much of the earth in future years -- if the planet continues to warm -- sound logical enough, but are they true?

We have long argued that these contentions are false, since in a CO2-accreting atmosphere -- such as we are destined to have for some time to come -- most plants prefer warmer temperatures, so that while warming gives them the opportunity to move poleward in latitude and upward in altitude at the cold-limiting boundaries of their ranges, it does not mandate that at the heat-limiting boundaries of their ranges they must move in these directions. Hence, with the greater over-lapping of vegetative species ranges that these phenomena portend for concomitant increases in atmospheric temperature and CO2 concentration, there should be a tendency for regional plant species richness to actually increase over the world; and it is our belief that this same type of range overlapping will apply to many of the world's animals that rely on these plants for their food and habitat.

In a study recently conducted by Gonzalez-Megias et al. (2008), the relative virtues of these competing hypotheses were put to the acid test of real-world observations, when they 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.

So what did they find?

The five researchers report -- in support, we believe, of our view of the matter -- that local community "colonisations exceeded extinctions," as "over twice as many sites gained species as lost species," such that "the average species richness of communities has increased." They also note that species abundances following colonization have likewise increased, due to "climate-related increases in the carrying capacity" of the land, which is something we also contend is happening throughout the world, as may be further verified by perusing the materials we have archived under the general heading of Greening of the Earth in our Subject Index.

In comparing their results with those of a broader range of pertinent animal studies, Gonzalez-Megias et al. write 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 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 suggest that "most of these taxa will also be experiencing slight community-level increases in species richness."

In light of these observations, plus a number of others that are highlighted in the second DVD of our Carbon Dioxide and the "Climate Crisis" series -- Avoiding Plant and Animal Extinctions -- it would appear that the world of nature is behaving just the opposite of how climate alarmists typically contend it should with respect to plant and animal biodiversity on a CO2-enriched and warming earth.

Sherwood, Keith and Craig Idso

Gonzalez-Megias, A., Menendez, R., Roy, D., Brereton, T. and Thomas, C.D. 2008. Changes in the composition of British butterfly assemblages over two decades. Global Change Biology 14: 1464-1474.

Hickling, R., Roy, D.B., Hill, J.K., Fox, R. and Thomas, C.D. 2006. The distributions of a wide range of taxonomic groups are expanding polewards. Global Change Biology 12: 450-455.