Climate is said to be a 'boundary value' problem - which relies on averaging over periods of 100 years or more. They are claimed to be accurate - although Don Easterbrook has written abour the potential for small errors in radiative forcing estimates, for instance, to propagate through the calculations to produce uncertainty bounds at 2100 of +/- 17 degrees C. Weather on the other is said to be an 'initial value' problem. Detailed knoweledge of initial conditions is required to define the evolution of weather over up to 10 days with reasonable accuraccy. After that calcultions diverge from reality.
There is an intermediate timeframe of slow oceanic changes on interannual to multidecadal timeframes. This in the interval where climate needs to be approached as an initial value problem like weather. No one has ever said that GCM are any good at all at the slow climate processes - which is an initial value problem. That is - climate models can and do diverge from reality over up to a couple of decades without being a theoretical problem. On Dec 28, 3:24 pm, James Annan <[email protected]> wrote: > Robbo wrote: > > Even such a seemingly simple question as to the rate of recent warming > > is subject to wide interpretation. Climate fluctuates strongly > > principally in line with ENSO. Large interannual and decadal changes > > in surface temperature makes the interpretation of trend sensitive to > > both the end points and to the length of the record. > > > Period Trend (degrees C/decade) > > > 1900 - 2008 0.07 > > 1945 2008 0.11 > > 1958 2008 0.13 > > 1979 1997 0.11 > > 1976 2008 0.17 > > > Table 1: A quick comparison of periods and temperature trends > > One interesting thing about that IMO is that despite the apparently wide > range of warming trends depending on endpoints, climate models manage to > match them all pretty well. > > James -- 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
