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Palaeoecology Reveals Real-World Biotic Responses to Global Warming
Volume 15, Number 9: 29 February 2012

In an invited review paper in Quaternary Science Reviews, Vegas-Vilarrubia et al. (2011) state that palaeoecology "is able to provide relevant inputs for conservation science and ecosystem management, especially for issues involving long-term processes, such as ecological succession, migration, adaptation, microevolution and extinction," and they say that this discipline "has become widely accepted, especially in the frame of ongoing and near-future global warming and its potential biotic consequences." So what does their review of this field of endeavor reveal about these matters?

For starters, the four researchers suggest that "current extinction estimates for the near-future should be revised in light of palaeoecological information, which shows that spatial reorganizations and persistence in suitable microrefugia have been more common than extinction during the Quaternary." And as a result of this fact, they say that "an interesting consequence is the possibility of new unknown species combinations with no modern analogues."

A couple of phenomena that come into play in these ecosystem transformations, according to the Spanish scientists, are acclimation and adaptation, "with the first relying on phenotypic plasticity and the second involving genetic changes of potential evolutionary significance," which they say "have been proposed as two possible reactions to future global warming and as alternatives to extinction by habitat loss."

As a result of these and other considerations, Vegas-Vilarrubia et al. note that "some authors propose that spatial reorganizations without extinction will be the dominant biotic response to the near-future global changes." But they say "it is also possible that ecosystems never attain equilibrium," and that "transient states perpetuate because of the recurrent action of environmental change." In fact, they say that "one of the main lessons from this is that ecosystems may express their resilience when confronted with environmental shifts by attaining several possible equilibrium states, as manifested in changes in biodiversity and/or composition, without losing their ecological functions."

Focusing on the global warming that occurred at the end of the Younger Dryas (~13,000 to 11,500 years ago), Vegas-Vilarrubia et al. write that it emerges as one of the more powerful analogues of projected global warming "because both magnitude and rates of change parallel those predicted for the present century." And they say that this prior real-world transformation "seems to have consisted of ecological reorganizations and changes in community composition because of differential species migration patterns and rates," while noting that "so far, it has not been possible to associate large-scale extinctions to the Younger Dryas climatic reversal."

In concluding their review, the four researchers say that palaeoecology "is becoming an important and necessary discipline needed to properly understand subjacent ecological processes." And it would appear from their analysis of this "necessary discipline" that it is providing some encouraging insights into some of earth's possible biotic futures.

Sherwood, Keith and Craig Idso

Reference
Vegas-Vilarrubia, T., Rull, V., Montoya, E. and Safont, E. 2011. Quaternary palaeoecoloogy and nature conservation: a general review with examples from the neotropics. Quaternary Science Reviews 30: 2361-2388.