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Contingencies and compounded rare perturbations dictate sudden distributional shifts during periods of gradual climate change.

ABSTRACT: Ecological responses to climate change may occur gradually with changing conditions, or they may occur rapidly once some threshold or "tipping point" has been reached. Here, we use a high-resolution, 30-year data set on the upper vertical limit of a high intertidal alga to demonstrate that distributional shifts in this species do not keep pace with gradual trends in air temperature or sea level, but rather occur in sudden, discrete steps. These steps occur when unusually warm air temperatures are associated with unusually calm seas and are contingent in the sense that neither atmospheric nor sea conditions by themselves were sufficient to generate the underlying physiological challenge. Shifts in the upper limit did not correlate with large environmental perturbations such as El Niños; rather, they appeared to be associated with stochastic departures from otherwise gradual environmental trends. Our results exemplify the view that multiple environmental factors should be considered when attempting to understand ecological responses to climate change. Furthermore, punctuated responses such as those we have identified urge caution when attempting to infer causal mechanisms and project future distributional shifts using data of limited temporal resolution or scope.

SUBMITTER: Harley CD

PROVIDER: S-EPMC2708713 | biostudies-literature | 2009 Jul

REPOSITORIES: biostudies-literature

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Contingencies and compounded rare perturbations dictate sudden distributional shifts during periods of gradual climate change.

Harley Christopher D G CD Paine Robert T RT

Proceedings of the National Academy of Sciences of the United States of America 20090617 27

Ecological responses to climate change may occur gradually with changing conditions, or they may occur rapidly once some threshold or "tipping point" has been reached. Here, we use a high-resolution, 30-year data set on the upper vertical limit of a high intertidal alga to demonstrate that distributional shifts in this species do not keep pace with gradual trends in air temperature or sea level, but rather occur in sudden, discrete steps. These steps occur when unusually warm air temperatures ar ...[more]

PMID: 19541649

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Contingencies and compounded rare perturbations dictate sudden distributional shifts during periods of gradual climate change.

Publications

Contingencies and compounded rare perturbations dictate sudden distributional shifts during periods of gradual climate change.

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