Volume 15, Number 24: 13 June 2012
In an impressive and enlightening review of the subject, Willis and MacDonald (2011) begin by noting that key research efforts have focused on extinction scenarios derived from "a suite of predictive species distribution models (e.g., Guisan and Thuiller, 2005)" - which are most often referred to as bioclimatic envelope models - that "predict current and future range shifts and estimate the distances and rates of movement required for species to track the changes in climate and move into suitable new climate space." And they write that one of the most-cited studies of this type - that of Thomas et al. (2004) - "predicts that, on the basis of mid-range climatic warming scenarios for 2050, up to 37% of plant species globally will be committed to extinction owing to lack of suitable climate space."
In contrast, the two researchers say that "biotic adaptation to climate change has been considered much less frequently." This phenomenon - which is sometimes referred to as evolutionary resilience - they describe as "the ability of populations to persist in their current location and to undergo evolutionary adaptation in response to changing environmental conditions (Sgro et al., 2010)." And they note that this approach to the subject "recognizes that ongoing change is the norm in nature and one of the dynamic processes that generates and maintains biodiversity patterns and processes," citing MacDonald et al. (2008) and Willis et al. (2009).
The aim of Willis and MacDonald's review, therefore, was to examine the effects of significant and rapid warming on earth's plants during several previous intervals of the planet's climatic history that were as warm as, or even warmer than, what climate alarmists typically predict for the next century. These intervals included the Paleocene-Eocene Thermal Maximum, the Eocene climatic optimum, the mid-Pliocene warm interval, the Eemian interglacial, and the Holocene. And it is important to note that this approach, in contrast to the approach typically used by climate alarmists, relies on empirical (as opposed to theoretical) data-based (as opposed to model-based), reconstructions (as opposed to projections) of the past (as opposed to the future).
And what were the primary findings of the two researchers?
As they describe them, in their own words, "persistence and range shifts (migrations) seem to have been the predominant terrestrial biotic response (mainly of plants) to warmer intervals in Earth's history," while "the same responses also appear to have occurred during intervals of rapid climate change." In addition, they make a strong point of noting that "evidence for global extinctions or extinctions resulting from reduction of population sizes on the scale predicted for the next century owing to loss of suitable climate space (Thomas et al., 2004) is not apparent." In fact, they state that sometimes an actual increase in local biodiversity is observed, the case for which we lay out in Section II (Physiological Reasons for Rejecting the CO2-Induced Global Warming Extinction Hypothesis) of our Major Report The Specter of Species Extinction: Will Global Warming Decimate Earth's Biosphere? Read it and rejoice!
Sherwood, Keith and Craig Idso
Guisan, A. and Thuiller, W. 2005. Predicting species distribution: offering more than simple habitat models. Ecology Letters 8: 993-1009.
MacDonald, G.M., Bennett, K.D., Jackson, S.T., Parducci, L., Smith, F.A., Smol, J.P. and Willis, K.J. 2008. Impacts of climate change on species, populations and communities: palaeobiogeographical insights and frontiers. Progress in Physical Geography 32: 139-172.
Sgro, C.M., Lowe, A.J. and Hoffmann, A.A. 2010. Building evolutionary resilience for conserving biodiversity under climate change. Evolutionary Applications 4: 326-337.
Thomas, C.D., Cameron, A., Green, R.E., Bakkenes, M., Beaumont, L.J., Collingham, Y.C., Barend, F., Erasmus, 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.
Willis, K.J., Bennett, K.D. and Birks, H.J.B. 2009. Variability in thermal and UV-B energy fluxes through time and their influence on plant diversity and speciation. Journal of Biogeography 36: 1630-1644.
Willis, K.J. and MacDonald, G.M. 2011. Long-term ecological records and their relevance to climate change predictions for a warmer world. Annual Review of Ecology, Evolution, and Systematics 42: 267-287.