How does rising atmospheric CO2 affect marine organisms?

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Surviving Global Warming Without Migrating Very Far
Seabra, R., Wethey, D.S., Santos, A.M. and Lima, F.P. 2011. Side matters: Microhabitat influence on intertidal heat stress over a large geographical scale. Journal of Experimental Marine Biology and Ecology 400: 200-208.

Working in the temperate-alpine zone near Furka Pass in the Swiss central Alps on three steep mountain slopes, Scherrer and Korner (2011) recently demonstrated how alpine plants can avoid extinction due to global warming by merely moving a few meters from one micro-habitat to another, since the heterogeneity of the landscape there provides temperature differences greater than IPCC warming projections for the next hundred years. Likewise, working within three different habitat types (woodland, heathland and grassland) in the United Kingdom, Suggitt et al. (2011) demonstrated that "thermal differences between habitats, and slope and aspects, were of the same order of magnitude as projected increases in global average surface temperatures," and they indicate that "in some cases, microclimate variation exceeded estimates of warming under all of the IPCC's emissions scenarios," suggesting that "populations may shift microhabitats (slopes, aspects and vegetation density) in response to inter-annual variation in the climate," including even the worst-case IPCC global warming projections.

What was done
In a study designed to explore the same phenomenon in a marine habitat, Seabra et al. (2011) examined the relative magnitudes of local-scale versus large-scale latitudinal patterns of the intertidal body temperatures of robolimpets: autonomous temperature sensor/loggers mimicking the visual aspect and temperature trajectories of real limpets, which were built as described by Lima and Wethey (2009). These temperatures were measured at thirty-minute intervals for recurring periods of 170 days at 13 exposed or moderately exposed rocky shores along 1500 km of the Atlantic coast of the Iberian Peninsula, where they were attached to steep rocky surfaces -- both north-facing (typically shaded) and south-facing (sun-exposed) -- at three different tidal heights covering the entire vertical range inhabited by real-life limpets.

What was learned
The "most relevant finding" of their study, in the words of the four researchers, was that "sunny versus shaded differences were consistently larger than the variability associated with [a] the seasons, [b] shore-specific characteristics (topography, orientation, wave exposure, etc.) and [c] shore level."

What it means
Seabra et al. say their findings emphasize the importance of analyzing temperature variability at scales relevant to the organisms being studied, "since the usage of sea surface temperature (SST) derived from remotely sensed data to model the distribution of intertidal species may be missing key environmental features," especially since their results "clearly show that other factors than SST play a much stronger role in determining the body temperatures of these organisms." They also suggest that "the observed temperature variability may explain the weak correlations found in many studies modeling the distribution of intertidal species using SST data (e.g. Lima et al., 2007b), which negatively impacts attempts of forecasting distributional changes in response to predicted climate warming."

Seabra et al. further state that "habitat heterogeneity as determined by surface orientation and, to a lesser extent, height on the shore may provide thermal refugia allowing species to occupy habitats apparently inhospitable when considering only average temperatures," and they state that "this may be important for understanding range shifts contrary to global warming predictions (e.g. Lima et al., 2007a, 2009; Hilbish et al., 2010)." Thus, they emphasize once again that "thermal heterogeneity within habitats must be fully understood in order to interpret patterns of biogeographic response to climate change." And if that is done correctly, it would appear that the "doom-and-gloom" predictions of the world's climate alarmists, as regards species extinctions in a warming world, may in reality be not all that "doomy and gloomy."

Hilbish, T.J., Brannock, P.M., Jones, K.R., Smith, A.B., Bullock, N.B. and Wethey, D.S. 2010. Historical changes in the distributions of invasive and endemic marine invertebrates are contrary to global warming predictions: the effects of decadal climate oscillations. Journal of Biogeography 37: 423-431.

Lima, F.P., Queiroz, N., Ribeiro, P.A., XSavier, R., Hawkins, S.J. and Santos, A.M. 2009. First record of Halidrys siliquosa (Linnaeus) Lyngbye in the Portuguese coast: counter-intuitive range expansion? Marine Biodiversity Records 2: 10.1017/S1755267208000018.

Lima, F.P., Ribeiro, P.A., Queiroz, N., Hawkins, S.J. and Santos, A.M. 2007a. Do distributional shifts of northern and southern species of algae match the warming pattern? Global Change Biology 13: 2592-2604.

Lima, F.P., Ribeiro, P.A., Queiroz, N., Xavier, R., Tarroso, P., Hawkins, S.J. and Santos, A.M. 2007b. Modeling past and present geographical distribution of the marine gastropod Patella rustica as a tool for exploring responses to environmental change. Global Change Biology 13: 2065-2077.

Lima, F.P. and Wethey, D.S. 2009. Robolimpets: measuring intertidal body temperatures using biomimetic loggers. Limnology and Oceanography: Methods 7: 347-353.

Scherrer, D. and Korner, C. 2011. Topographically controlled thermal-habitat differentiation buffers alpine plant diversity against climate warming. Journal of Biogeography 38: 406-416.

Suggitt, A.J., Gillingham, P.K., Hill, J.K., Huntley, B., Kunin, W.E., Roy D.B. and Thomas, C.D. 2011. Habitat microclimates drive fine-scale variation in extreme temperatures. Oikos 120: 1-8.

Reviewed 24 August 2011