It is more complicated than this. However, the reason that we use rad forcing is that we generally assume that forcings can be added (as does IPCC). I have looked at this with forcings that are in the 21st century range. Within the uncertainties in calculating forcings for individual items, forcings can be added at least for global forcing. The uncertainties are such that it is impossible to disprove additivity. I suspect that additivity works less well regionally -- but the noise is greater so the task of disproving additivity is even harder here. I do not know anyone who has looked at this.
A more important issue is whether additivity works for responses (temp. precip. etc). We have looked at this extensively with many different forcings and forcing combinations. For most things, additivity holds (so the issue of forcing additivity becomes moot). There seem to be problems when trop. ozone is one of the forcings. Tom. ++++++++++++++++++++++ > You can of course add radiative forcing "linearly". (What other kind of > addition is there?) > > An important question is whether climate response to the sum of radiative > forcings is the same as the sum of the climate responses to individual > radiative forcings. > > The answer to this question depends on the size of the perturbation and > your > tolerance for approximation. > > Recall the maxim: "*To first order, everything is linear !!"* > > ( More strictly speaking, "*To first order, differentiable functions are > linear.*" ) > > > > On Wed, Dec 31, 2008 at 11:13 AM, Stuart Strand > <[email protected]>wrote: > >> >> Is radiative forcing additive linearly? >> >> = Stuart = >> >> Stuart E. Strand >> 167 Wilcox Hall, Box 352700, Univ. Washington, Seattle, WA 98195 >> voice 206-543-5350, fax 206-685-3836 >> http://faculty.washington.edu/sstrand/ >> >> Using only muscle power, who is the fastest person in the world? >> Flying start, 200 m: 82.3 mph! >> http://en.wikipedia.org/wiki/Sam_Whittingham >> Hour http://en.wikipedia.org/wiki/Hour_record >> 55 miles, upside down, backwards, and head first! >> >> >> > >> > > > > --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "geoengineering" group. 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/geoengineering?hl=en -~----------~----~----~----~------~----~------~--~---
