Slide 30: Linear and non linear responses
Many climatic responses to changing conditions are linear in nature (either logarithmically through feedback mechanisms or as a flat trend line).
However, palaeoclimatological evidence points towards a number of prehistoric periods of extremely rapid climate change.
This is typical of non-linear systems with multiple stable equilibria (as detailed in)(Lorenz, 1993).
In this situation, when conditions are pushed towards a "threshold value", the transition to a new mode of operation, or new equilibrium value, may be exceedingly rapid.
This has also been seen recently in changes in large scale circulation patterns detected by instrumental readings, and in contemporary observations of regional weather patterns. (Corti et al, 1999).
Thus, it is entirely possible that certain effects will not follow a linear trend, and we could see rapid shifting of some aspects of the climate, as detailed on the next slide.