A Nonlinear Dynamical Perspective on Climate Prediction

A nonlinear dynamical perspective on climate prediction is outlined, based on a treatment of climate as the attractor of a nonlinear dynamical systemDwith distinct quasi-stationary regimes. The main application is toward anthropogenic climate change, considered as the response ofDto a small-amplitude imposed forcing f. The primary features of this perspective can be summarized as follows. First, the response to f will be manifest primarily in terms of changes to the residence frequency associated with the quasi-stationary regimes. Second, the geographical structures of these regimes will be relatively insensitive to f. Third, the large-scale signal will be most strongly influenced by f in rather localized regions of space and time. In this perspective, the signal arising from f will be strongly dependent ofD’s natural variability. A theoretical framework for the perspective is developed based on a singular vector decomposition ofD’s tangent propagator. Evidence for the dyamical perspective is drawn from a number of observational and modeling studies of intraseasonal, interannual, and interdecadal variability, and from climate change integrations. It is claimed that the dynamical perspective might resolve the apparent discrepancy in global warming trends deduced from surface and free troposphere temperature measurements. A number of specific recommendations for the evaluation of climate models are put forward, based on the ideas developed in this paper.