«In comparison to our toy
model, a natural system, such as the atmosphere, a river
basin, etc.: (a) is much more complex; (b) has time - varying inputs and outputs; (c) has spatial extent, variability and dependence (in addition to temporal); (d) has greater dimensionality (virtually infinite); (e) has dynamics that to a large extent is unknown and difficult or impossible to express deterministically; and (f) has
parameters that are unknown.