Dear Hank, A new voice is welcome. As a result I have signed up again. There is an almost conversational aspect to this forum which I find appealing - but there is a need to be polite and urbane.
Swanson and Latif are talking about a return to warming in a decade or 2. There are a couple of elements to understand. First of all the 'true' warming signal identifed by Swanson, and consistent with Latif, is about 0.1 degrees/decade. That is about half of warming between 1976 and 1998 was natural. I will copy a quote from Anastasios Tsonis on natural variability. http://www.wisn.com/weather/18935841/detail.html "But if we don't understand what is natural, I don't think we can say much about what the humans are doing. So our interest is to understand -- first the natural variability of climate -- and then take it from there. So we were very excited when we realized a lot of changes in the past century from warmer to cooler and then back to warmer were all natural," Tsonis said. "Tsonis said he thinks the current trend of steady or even cooling earth temps may last a couple of decades or until the next climate shift occurs." The lower rate of recent (reputed) anthropogenic warming has implications for 'average conditions' over the longer term - a much lower envelope of climate risk. This is the take away message - a lower average potential for global warming. I am not so sure, however, that 'average conditions' captures the true potential for abrupt climate change in a dynamic and complex nonlinear system. As Swanson says - 'there are no guarantees to how climate may respond.' I suppose both Swanson and Latif would find it difficult to state categorically that there is a risk that the planet will cool longer term - the debate is too heated and polarised. Regardless, climate reality is abrupt change rather than global warming. You are quoting words at me - but you need to understand the meaning of complex and nonlinear. There is a 2002 NAS publication: Abrupt Climate Change: Inevitable Surprises, which is worth a read. My political take on this is that any possibility of limiting carbon emmissions (of which I am in favour) in the near future has been lost as a result of scientific arrogance, political opportunism and green overreach. The majority of people are seeing no temperature rise and there remains the prospect of no temperature rise (minimum) for another decade or 2. A La Nina is on the way, the peak of solar cycle 24 around 2013 is being predicted by NASA to be the smallest since 1928 and the NOA has switched with a vengeance. I have been studying decadal changes in Australian hydrology for 20 years. When I realised 10 years ago that there were implications for decadal variations of global temperature, I rang up Australia's leading hyroclimatologist, Bruce (he is in the Philosophy Department of the University of Wooloomooloo) and asked him if I were going mad. It is perhaps true that I am mad but I was right. It is very cold comfort to make a bad pun. Cheers Robert On Jan 23, 4:01 pm, Hank Roberts <[email protected]> wrote: > Bzzzt!http://www.realclimate.org/index.php/archives/2009/07/warminginterrup... > The main post begins: > "A guest commentary by Kyle Swanson – University of Wisconsin- > Milwaukee > I am quite humbled by the interest that has been generated by our > paper “Has the climate recently shifted?” (Swanson and Tsonis, 2009), > and would like the thank the RealClimate editors for the opportunity > to give my perspective on this piece. ..." > and after a discussion of the paper, it ends: > "as the temperature anomaly associated with this jump dissipates, we > hypothesize that the climate system will return to its signal as > defined by its pre-1998 behavior in roughly 2020 and resume warming. > > What do our results have to do with Global Warming, i.e., the century- > scale response to greenhouse gas emissions? VERY LITTLE, contrary to > claims that others have made on our behalf. Nature (with hopefully > some constructive input from humans) will decide the global warming > question based upon climate sensitivity, net radiative forcing, and > oceanic storage of heat, not on the type of multi-decadal time scale > variability we are discussing here. However, this apparent impulsive > behavior explicitly highlights the fact that humanity is poking a > complex, nonlinear system with GHG forcing – and that there are no > guarantees to how the climate may respond." > ------------ > > > > > > > 2010/1/21 Robbo <[email protected]> > ... > > > But another expert, Professor Anastasios Tsonis, head of the > > > University of Wisconsin Atmospheric Sciences Group.... > > -- 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. 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