On Dec 12, 11:06 am, "[email protected]" <[email protected]> wrote: > ... > I believe that we have limited knowledge about past changes in > relative humidity. ... Indeed so, except for a few obvious bits: assume a great supply of CCNs (correct except possibly for the Southern Ocean and Antarctica). Then if relative humidity goes up, clouds form and the moisture precipitates out. If relative humidity goes down... So measure global precipitation; it hasn't changed much at all in over a quater century; ergo...
Now the GCMs do not assume a (nearly) constant relative humidity, but rather attempt to resolve the underlying physics of the atmosphere. Nearly constant relative humidity pops out of the runs. For a 2003 CE study of what more was needed at that time, see http://www.nap.edu/catalog.php?record_id=10850#toc My understanding is that most of those issues have been adequately resolved; the current pressing mattrs are aerosols and ocean heat uptake. As for the more general point about sudden changes, the situation in the arctic is certainly a reminder that the cryosphere is also currently poorly understood; Jeff Masters certainly has a point! -- 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
