How does rising atmospheric CO2 affect marine organisms?

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Climate Envelope Models of Plants and Animals
Nogues-Bravo, D. 2009. Predicting the past distribution of species climatic niches. Global Ecology and Biogeography 18: 521-531.

The author writes that climate envelope models (CEMs) -- which are often employed to predict species responses to global warming (and whether or not a species will be able to survive projected temperature increases) -- "are sensitive to theoretical assumptions, to model classes and to projections in non-analogous climates, among other issues." So how appropriate are they for this particular purpose, i.e., determining whether or not a particular species will be driven to extinction by hypothesized planetary warming?

What was done
In an exercise that addresses this important question, Nogues-Bravo reviews the scientific literature pertaining to the issue.

What was learned
In the researcher's own words, "the studies reviewed: (1) rarely test the theoretical assumptions behind niche modeling such as the stability of species climatic niches through time and the equilibrium of species with climate; (2) they only use one model class (72% of the studies) and one palaeoclimatic reconstruction (62.5%) to calibrate their models; (3) they do not check for the occurrence of non-analogous climates (97%); and (4) they do not use independent data to validate the models (72%)."

What it means
According to Nogues-Bravo, "ignoring the theoretical assumptions behind niche modeling and using inadequate methods for hindcasting," may well produce "a cascade of errors and na´ve ecological and evolutionary inferences." Hence, he concludes "there are a wide variety of challenges that CEMs must overcome [italics added] in order to improve the reliability of their predictions through time." And until these challenges are met, climate-alarmist contentions of impending species extinctions must be considered little more than guesswork.

Reviewed 23 December 2009