It is more involved than simply averaging over more than 30 years. This as stated gives the wrong answer. The average for a 20 to 40 year Drought Dominated Regime (DDR) is about 23% less than the 100 year average. Conversely, the average for a Flood Dominated Regime (FDR)is about 23% higher than the 100 year average. So to calculate the likely average rainfall over the next ten years - you first have to determine whether we are in a DDR or FDR.
We have entered a cool phase of the PDO - which is associated with more intense and frequent La Nina over 20 to 40 years. So Australia is in a FDR - but there are implications for global hydrology. The likelihood of more rain in the eastern hemisphere and less in the west over the next 10 to 30 years. ENSO of course also has implications for global surface temperature. I believe it might have something to do with global cloud cover changes due to changes in Walker and Hadley circulation - and the location of the intertropical convergence zone - as reinforcing mechanisms. I think it might be driven by changes in UV in the 22 year Hale cycle - feeding into downwelling in the Antarctic vortex - which in turn drives changes in cold sea surface currents moving up the Antarctic Penisula to South America. In turn, of course, driving the thermal evolution of ENSO. The cold water pool off South America can be seen: http://www.osdpd.noaa.gov/data/sst/anomaly/2010/anomnight.4.22.2010.gif A discussion of ENSO as a non-linear and non-Gaussian process can be found here: http://www.nonlin-processes-geophys.net/16/453/2009/npg-16-453-2009.pdf Regardless - the cool Pacific mode is associated with 20 to 40 years of a cooling influence on global surface temperatures. The 'cycles' that Judith Curry was talking about - linked to in the Swedish thread. It allows for a prediction of sorts - 20 to 40 years of a surface cooling influence from 2001. A decade of non-warming thus far not enough? 'This paper provides an update to an earlier work that showed specific changes in the aggregate time evolution of major Northern Hemispheric atmospheric and oceanic modes of variability serve as a harbinger of climate shifts. Specifically, when the major modes of Northern Hemisphere climate variability are synchronized, or resonate, and the coupling between those modes simultaneously increases, the climate system appears to be thrown into a new state, marked by a break in the global mean temperature trend and in the character of El Nino Southern Oscillation variability. Here, a new and improved means to quantify the coupling between climate modes confirms that another synchronization of these modes, followed by an increase in coupling occurred in 2001/02. This suggests that a break in the global mean temperature trend from the consistent warming over the 1976/77–2001/02 period may have occurred.' https://pantherfile.uwm.edu/kswanson/www/publications/2008GL037022_all.pdf Puting on a serious face - I don't really think it is a good idea to arbitrarily change the composition of the atmosphere but the lack of warming has real political consequences. Instead of insisting that it isn't happening - or is not meaningful as it is only 10 years thus far - you need to at least entertain the possibility of 20 to 40 years of cooling. On Apr 23, 8:45 am, "David B. Benson" <[email protected]> wrote: > And the problem if one doesn't use at least 30 years for > climate:http://BartonPaulLevenson.com/30Years.html > > -- > 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 > athttp://groups.google.com/group/globalchange -- 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
