The Royal Society Climate change: a summary of the science I September 2010
'In principle, changes in climate on a wide range of timescales can also arise from variations within the climate system due to, for example, interactions between the oceans and the atmosphere; in this document, this is referred to as “internal climate variability”. Such internal variability can occur because the climate is an example of a chaotic system: one that can exhibit complex unpredictable internal variations even in the absence of the climate forcings discussed in the previous paragraph. http://the-eggs.org/bookreviews.php?id=55 'The readers of Nonlinear Processes in Geophysics are well aware that the solutions to nonlinear deterministic-like equations governing weather evolution are most probably chaotic in space and time: a small scale truncation can in a finite time generate large-scale errors. This behaviour has been conjectured precisely, for the prototypical Navier-Stokes equations and is subject to a million-dollar Clay Mathematics Millennium prize. Without awaiting this mathematical conclusion, statistical theories of turbulence and corresponding stochastic models are already in constant use in a wide range of fluid mechanics applications. The book “Stochastic Physics and Climate Modelling” edited by Palmer and Williams (2010) pushes forward these ideas in an original manner to the even more challenging and wider theme of climate change, which has an estimated worth of one trillion dollars (Stern, 2006), as recalled by the editors in their breathtaking preface. This book indeed promotes the use of stochastic, or random, processes to understand, model and predict our climate system, and in particular to resolve the presently considerable uncertainty in global and regional climate predictions.' Irreducible imprecision in atmospheric and oceanic simulations James C. McWilliams 2007 PNAS - http://www.pnas.org/content/104/21/8709.full 'Sensitive dependence and structural instability are humbling twin properties for chaotic dynamical systems, indicating limits about which kinds of questions are theoretically answerable. They echo other famous limitations on scientist’s expectations, namely the undecidability of some propositions within axiomatic mathematical systems (Godel’stheorem) and the uncomputability of some algorithms due to excessive size of the calculation'. http://journals.ametsoc.org/doi/pdf/10.1175/2009BAMS2712.1 'There is a delicate web of interactions among the different components of the climate system. The interplay among the time scales is quite intricate, as the fast atmosphere interacts with the slow upper ocean and the even slower sea ice and deep-soil and groundwater processes. Spatial scales are tightly connected too, as small-scale cloud systems, for instance, affect the large-scale energy balance. Furthermore, everything is connected by water in its various forms. Water flows easily from place to place and exchanges energy with the environment every time it changes phase. Evaporation, condensation, freezing, and melting processes must be taken into account and evaluated as accurately as possible. The past 40 years of climate simulation have made it apparent that no shortcut is possible; every process can and ultimately does affect climate and its variability and change. It is not possible to ignore some components or some aspects without paying the price of a gross loss of realism.' The Navarra et al conclusion that “Such models have become the central pillar of the quantitative scientific approach to climate science because they allow us to perform “crucial” experiments under the controlled conditions that science demands” Nonetheless, the real pursuit of science is in theory and observation. 'In a truly nonlinear setting, indeterminacy in the size of the response is observed only in the vicinity of tipping points. We show, in fact, that small disturbances cannot result in a large-amplitude response, unless the system is at or near such a point. We discuss briefly how the distance to the bifurcation may be related to the strength of Earth's ice-albedo feedback.' Your reference - it doesn't mean that climate is linear - just that large change happens at tipping points. Duh. 'EBMs exhibit two saddle-node bifurcations, more recently called "tipping points," which give rise to three distinct steady-state climates, two of which are stable. Such bistable behavior is, furthermore, supported by results from more realistic, nonequilibrium climate models.' Neither the original or the original article is well founded in observation - a 2 or 3 state model can't be compared with multiple equilibria of the real climate system. http://isccp.giss.nasa.gov/zFD/an9090_SWup_toa.gif - you need to include clouds in the delicate web of interactions. I am seriously disturbed that don't think that this is a logical non sequiter - from linear to nonlinear - but still you think it makes a point? On Sep 27, 6:50 am, "David B. Benson" <[email protected]> wrote: > The abstract of > Zaliapin, I. and Ghil, M.: > Another look at climate sensitivity, > Nonlin. Processes Geophys., 17, 113-122, > doi:10.5194/npg-17-113-2010.http://www.nonlin-processes-geophys.net/17/113/2010/npg-17-113-2010.html > appears relevant to this discussion > (if we can call it that). > [Thanks to Chris Colose] -- 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
