There is a lot of evidence for abrupt climate change - by definition change that is disproportionate to the forcing - a nonlinear response that is a characteristic of complex systems. There are several good resources - the NRC document Abrupt Climate Change: Inevitable Surprises I quoted in the beginning is a readable and accessable resource.
As for the distinction between weather and climate. I have quoted this before also. 'The global coupled atmosphere–ocean–land–cryosphere system exhibits a wide range of physical and dynamical phenomena with associated physical, biological, and chemical feedbacks that collectively result in a continuum of temporal and spatial variability. The traditional boundaries between weather and climate are, therefore, somewhat artificial. The large-scale climate, for instance, determines the environment for microscale (1 km or less) and mesoscale (from several kilometers to several hundred kilometers) processes that govern weather and local climate, and these small-scale processes likely have significant impacts on the evolution of the large-scale circulation. The accurate representation of this continuum of variability in numerical models is, consequently, a challenging but essential goal. Fundamental barriers to advancing weather and climate prediction on time scales from days to years, as well as longstanding systematic errors in weather and climate models, are partly attributable to our limited understanding of and capability for simulating the complex, multiscale interactions intrinsic to atmospheric, oceanic, and cryospheric fluid motions.' A UNIFIED MODELING APPROACH TO CLIMATE SYSTEM PREDICTION by James Hurrell, Gerald A. Meehl, David Bader, Thomas L. Delworth , Ben Kirtman, and Bruce Wielicki: BAMS December 2009 | 1819: DOI: 10.1175/2009BAMS2752.1 I don't know what to say about the last glacial max. Models with fixed ice sheets can't possibly be used for modelling glacial conditions. On Feb 2, 4:35 am, Phil Hays <[email protected]> wrote: > On Mon, 2010-02-01 at 02:48 -0800, Robert Indigo Ellison wrote: > > But a metaphor for what? I know that global warming is involved > > somewhere but I can’t quite make the connection. > > ... > > > There is a need to think in terms of total systems - difficult as > > there are so many gaps in understanding and lack of data - rather than > > trying to isolate a specific factor in a causative chain. It is > > useful to think in terms of climate shifts rather than global warming > > necessarily. I think it is helpful to have some understanding of > > complex systems theory - as a metatheory, an organising principle, for > > ideas about abrupt climate change. > > The connection is that both airflow over a wing is chaotic and climate > is chaotic, yet meaningful causal statements can be made about both. > > As far as I understand it: Climate is usually weakly chaotic. It is, > after all, just the average of weather. So there is clearly a limit to > the short term accuracy of predictions. However, there is a lot of > evidence that climate is not usually strongly chaotic, and thus longer > term predictions are more reliable. > > Airflow over wings is usually weakly chaotic. Even in ideal conditions, > 99% of the surface of the wing of the Wright Flyer had chaotic flow, aka > turbulent flow. And in cases flying in turbulent air, often the case > near the ground, 100% of the air flow on any wing can be turbulent. Yet > that doesn't mean that complex system theory is needed to design an > aircraft, or to fly one. > > > Although there are climate models their veracity has not been > > demonstrated – they are best described as plausible. The only > > reasonable confirmation is in comparison with an untuned reality. It's > > not looking real good at the moment. > > As for today's weather, exactly how closely could a climate model > predict this year's weather? Where is the boundary between climate and > weather? > > As for untuned reality, the cross check between models and the Last > Glacial Maximum seems to me to be a fair confirmation. > > -- > Phil Hays <[email protected]> -- You received this message because you are subscribed to the Google Groups Global Change ("globalchange") newsgroup. Global Change is a public, moderated venue for discussion of science, technology, economics and policy dimensions of global environmental change. Posts will be admitted to the list if and only if any moderator finds the submission to be constructive and/or interesting, on topic, and not gratuitously rude. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/globalchange
