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Mass Extinction or Massive Exaggeration?  New Study Makes Monumental Claim Based on Erroneous Premise
Volume 7, Number 2: 14 January 2004

Thomas et al. (2004) developed projections of future habitat distributions for over one thousand different plants and animals, which they used to produce estimates of extinction probabilities associated with IPCC-inspired climate change scenarios for the year 2050.  Prior to publication, their results were widely disseminated to the popular media, which generally portrayed them as first-rate scientific findings that depicted the inevitable annihilation of over a million unique species if anthropogenic CO2 emissions are not quickly and dramatically reduced.  This news was viewed by climate alarmists as an opportunity to once again browbeat humanity in an attempt to get the world community of nations - and the United States in particular - to accept their demands for draconian reductions in the use of fossil fuels, as they once again demonstrated the shallowness of their understanding of how the world of nature really works.

The nineteen scientist-authors of the paper that created all the fuss began their analysis by determining the "climate envelopes" of a total of 1,103 species.  Each of these envelopes represents the current climatic conditions under which a given species is found in nature.  Then, after seeing how the identically-defined habitat area of each of the studied species would be expected to change in response to an increase in temperature (most habitat areas declined), they used an empirical power-law relationship that relates species number to area size to make their final extinction probability calculations.

At first blush, this procedure seems reasonable enough, all else being equal.  But "all else" is almost always not equal when something changes in the real world; and the case in point is no exception.  Accompanying a CO2-induced increase in air temperature, there is always, by definition, a concomitant increase in the air's CO2 concentration; and this concurrent phenomenon, the physiological effects of which on earth's plants are totally ignored by Thomas et al., has some critically important consequences that dramatically alter their conclusions.  In fact, these consequences actually refute their conclusions.

The key fact ignored by the nineteen scientists (which clearly demonstrates there is little strength in numbers when it comes to discerning truth from error) is that plants in a CO2-enriched atmosphere generally prefer warmer temperatures than they do when exposed to air of the current CO2 concentration.  Many experiments convincingly demonstrate, for example, that a doubling of the air's CO2 concentration typically boosts the optimum temperature for plant photosynthesis by several degrees Centigrade, and that it raises the temperature at which plants experience heat-induced death by about the same amount, as is thoroughly documented and discussed in our report The Specter of Species Extinction: Will Global Warming Decimate Earth's Biosphere?  And, of course, extra CO2 in the air generally always leads to greater rates of photosynthesis and biomass production (see our website's Plant Growth Data section), as well as a heightened ability to successfully deal with most naturally-occurring environmental stresses and resource limitations (Idso and Idso, 1994).

As a result of these CO2-induced changes in their basic physiological behavior, earth's plants would not be eliminated from large portions of their current natural habitats near the heat-limited boundaries of their ranges in a CO2-enriched world of the future, even if temperatures were to unexpectedly rise as high as is unrealistically predicted by climate alarmists, because all types of vegetation, with the help of the extra CO2, would be able to tolerate much warmer living conditions than they do currently.  Simultaneously, at the cold-limited boundaries of their present ranges, they would have an opportunity to expand into areas that warmed and thereby invited their colonization.  Hence, with stable heat-limited boundaries and poleward- and upward-moving cold-limited boundaries, earth's plants in a CO2-enriched and warmer world would actually experience increases in the sizes of the territories they inhabit, making them not more likely but less likely to experience extinction.

Either not knowing or refusing to acknowledge these facts (both of which breaches of good science procedure and policy formulation are totally unacceptable), Thomas et al. cite the similar warming-induced extinction papers of Root et al. (2003) and Parmesan and Yohe (2003) as the primary justification for their approach to the issue, apparently oblivious of the fact that the real-world observations contained in the host of studies these authors cite in support of their conclusions actually argue against the validity of their mass extinction claims, as we have demonstrated in exhaustive detail in our Specter of Species Extinction report.

It is likewise ironic that Thomas et al. attempt to justify their sweeping conclusions by acknowledging that climate change over the past thirty years has been implicated in only a single "species-level extinction," citing the study of Pounds et al. (1999) in this regard.  If they had read our Specter of Species Extinction report, however, they would have learned that this claim, too, has been convincingly refuted, in this case by Lawton et al. (2001), who have demonstrated [see our Editorial of 21 Nov 2001] that the cause of the putative extinction was not an increase in temperature brought on by increasing anthropogenic CO2 emissions, but a local upwind deforestation of adjacent lowlands that led to increased convective and orographic cloud bases that resulted in a reduced supply of moisture to the habitat area studied by Pounds et al., which was the critical factor in negatively impacting local frog and toad populations.

In further demonstrating the wrong-headedness of the papers of Thomas et al. and their like-minded predecessors, Idso et al. (2003) note that with stable heat-limited boundaries and poleward- and upward-moving cold-limited boundaries, there would clearly be more overlapping of species ranges in a CO2-enriched warmer world, which would produce significant increases in local biodiversity.  What is more, we demonstrate in our report, using the very studies said by Root et al. (2003) and Parmesan and Yohe (2003) to imply the opposite, that what our analysis suggests has indeed been observed to be the case in many real-world species surveys of both plants and animals, several of the scientific reports of which ironically include Thomas himself as an author!

In concluding, we note that the media frenzy that characterized the immediate aftermath of the publication of the paper of Thomas et al. is a ringing testament to the sorry fact that the more outrageous the false claims of IPCC functionaries and climate alarmists become, the greater is the publicity they tend to generate.  Be that as it may, the media outlets that continue to unabashedly promote such demonstrably false notions will ultimately find their credibility eroded beyond repair, as will the scientists who spawn such stories, for the truth cannot be continuously denied with impunity.  It will prevail, and to the ever-lasting regret of those who knowingly championed its opposite.

Sherwood, Keith and Craig Idso

Idso, K.E. and Idso S.B.  1994.  Plant responses to atmospheric CO2 enrichment in the face of environmental constraints: A review of the past 10 years' research.  Agricultural and Forest Meteorology 69: 153-203.

Idso, S.B., Idso, C.D. and Idso, K.E.  2003.  The Specter of Species Extinction: Will Global Warming Decimate Earth's Biosphere?  Center for the Study of Carbon Dioxide and Global Change, Tempe, Arizona, USA.

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.

Parmesan, C. and Yohe, G.  2003.  A globally coherent fingerprint of climate change impacts across natural systems.  Nature 421: 37-42.

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.

Root, T.L., Price, J.T., Hall, K.R., Schneider, S.H., Rosenzweig, C. and Pounds, J.A.  2003.  Fingerprints of global warming on wild animals and plants.  Nature 421: 57-60.

Thomas, C.D., Cameron, A., Green, R.E., Bakkenes, M., Beaumont, L.J., Collingham, Y.C., Erasmus, B.F.N., Ferreira de Siqueira, M., Grainger, A., Hannah, L., Hughes, L., Huntley, B., van Jaarsveld, A.S., Midgley, G.F., Miles, L., Ortega-Huerta, M.A., Peterson A.T., Phillips, O.L. and Williams, S.E.  2004.  Extinction risk from climate change.  Nature 427: 145-148.