The Seven Deadly "Sins of Omission" that Plague Projections of Future Spatial Distributions of Marine Life

Planque et al. (2011) state that the "projection of future spatial distributions of marine populations is a central issue for ecologists and managers," and they indicate that "the measure of projection uncertainty is particularly important, because projections can only be useful if they are given with a known and sufficiently high level of confidence." In this regard, therefore, they list seven types of uncertainty that need to be addressed in making projections of spatial redistributions of marine species in response to changes in atmospheric composition (such as CO₂ concentration) and climate (such as global warming). These uncertainties include those associated with (1) the observation process, (2 and 3) conceptual and numerical model formulations, (4) parameter estimates, (5) model evaluation, (6) appropriate consideration of spatial and temporal scales, and -- perhaps most importantly of all -- (7) the potential of adaptation of living systems.

To analyze and evaluate how these different types of uncertainty are currently being considered in marine research, Planque et al. conducted a survey of the relevant scientific literature that was published over the period 2005-2009; and based on the information contained in the 75 pertinent publications they selected for study, they calculated how frequently each of the seven types of uncertainty was considered.

The three researchers, as they describe it, found that "little attention is given to most sources of uncertainty, except for uncertainty in parameter estimates." And with respect to the all-important "adaptability of living systems," they say that "anticipated effects of perturbations on ecosystems are commonly derived from past observation of the effects of similar perturbations," but they are quick to note that "ecosystems are both complex and adaptive," and that "they present a high degree of non-linearity and a strong dependence on historical contingencies," citing the work of Levin (1998, 2002, 2005), all of which leads to their conclusion that "the assumption that future responses will resemble past ones is therefore unlikely to hold usually, at least beyond a certain time horizon."

In light of their findings, Planque et al. state -- with respect to projections of future ranges of marine plant and animal populations -- that "most current projections are expected to be far less reliable than usually assumed." In fact, they conclude that these assessments are so tenuous that "unless uncertainty can be better accounted for, such projections may be of limited use, or even risky to use for management purposes."

Additional References
Levin, S.A. 1998. Ecosystems and the biosphere as complex adaptive systems. Ecosystems 1: 431-436.

Levin, S.A. 2002. Complex adaptive systems: exploring the known, the unknown and the unknowable. Bulletin of the American Mathematical Society 40: 3-19.

Levin, S.A. 2005. Self-organization and the emergence of complexity in ecological systems. BioScience 55: 1075-1079.