How does rising atmospheric CO2 affect marine organisms?

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Will It Be Species Extinction or Species Persistence?
Denny, M.W., Dowd, W.W., Bilir, L., and Mach, K.J. 2011. Spreading the risk: Small-scale body temperature variation among intertidal organisms and its implications for species persistence. Journal of Experimental Marine Biology and Ecology 400: 175-190.

In introducing the rationale for their study, the authors write that "rising concentrations of atmospheric carbon dioxide and other greenhouse gases are currently" -- and we would here insert the words claimed to be -- "causing a worrisome increase in globally averaged air temperature (IPCC, 2007)," while noting that, as a result, "the scientific community has mobilized to predict the ecological effects of consequent climate change." And in this regard they indicate that "the intertidal zone of wave-swept rocky shores is a potentially useful system in which to monitor, experimentally manipulate, and possibly forecast the ecological consequences of impending changes in environmental temperature."

What was done
Working at Stanford University's Hopkins Marine Station in Pacific Grove, California, USA, Denny et al., as they describe it, "conducted intensive field experiments to quantify inter-individual variation in body temperature among organisms and surrogate organisms at a typical intertidal site," after which they used the data they collected "to characterize micro-scale variation in potential thermal stress," noting that "variegated topography and the ever-changing pattern of the tides can cause organisms in close proximity to experience dramatically different thermal environments (e.g., Harley and Helmuth, 2003; Denny et al., 2006; Harley, 2008; Miller et al., 2009)."

What was learned
In the words of the Stanford University scientists, they discovered that "the within-site variation in extreme temperatures rivaled (and in some cases greatly exceeded) variation among sites along fourteen degrees of latitude (1660 km of Pacific shoreline)," which observation suggests, in their words, that "small-scale spatial variation in temperature can reduce the chance of local extirpation that otherwise would accompany an increase in average habitat temperature or an increase in the frequency of extreme thermal events."

What it means
Denny et al. conclude that "by highlighting the important role of within-site variability (both of temperature and tolerance) in the persistence of intertidal populations," their study should "foster further research into the biophysical, physiological, behavioral, and genetic interactions underlying ecological dynamics on wave-washed shores" -- with analogous implications for most other ecosystems -- which approach to the subject is a far, far cry from the standard climate envelope approach that is typically used by the world's climate alarmists in drawing their chilling conclusions regarding the impending extinctions of a goodly portion of the planet's plant and animal species.

Denny, M.W., Miller, L.P. and Harley, C.D.G. 2006. Thermal stress on intertidal limpets: long-term hindcasts and lethal limits. Journal of Experimental Biology 209: 2420-2431.

Harley, C.D.G. 2008. Tidal dynamics, topographic orientation, and temperature-mediated mass mortalities on rocky shores. Marine Ecology Progress Series 371: 37-46.

Harley, C.D.G. and Helmuth, B.S.T. 2003. Local- and regional-scale effects of wave exposure, thermal stress, and absolute versus effective shore level on patterns of intertidal zonation. Limnology and Oceanography 48: 1498-1508.

IPCC. 2007. Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge University Press, Cambridge, United Kingdom.

Miller, L.P., Harley, C.D.G. and Denny, M.W. 2009. The role of temperature and desiccation stress in limiting the small-scale distribution of the owl limpet, Lottia gigantean. Functional Ecology 23: 292-302.

Reviewed 10 August 2011