Tsonis et al (2007) and Swanson and Tsonis (2009) results are not based on correlation. They used a relatively new network approach to analysing complex systems. They used 4 ocean/climate indices - the Pacific Decadal Oscillation (PDO), the North Atlantic Oscillation (NAO), the El Nin˜o/Southern Oscillation(ENSO), and the North Pacific Oscillation (NPO) and show that climate behaves on multidecadal timeframes as you would expect it to - as a complex system in terms of complex systems theory. Climate bahaves as a forced nonlinear oscillator at scales frome ENSO to ice ages and beyond. This supports your argument rather than otherwise. Small changes in initial conditions leading to large changes in climate.
See for instnce - Slowing down as an early warning signal for abrupt climate change - Vasilis Dakos*, Marten Scheffer*†, Egbert H. van Nes*, Victor Brovkin‡§, Vladimir Petoukhov‡, and Hermann Held‡: www.pnas.org/cgi/doi/10.1073/pnas.0802430105 The 2007 paper from Tsonis et al- A new dynamical mechanism for major climate shifts - is the more important in giving the background ideas. The 2009 Swanson and Tsonis paper is an update. There is no such thing as simple causality in climate - climate has many degrees of freedom that are dynamically interactive. There is no chicken and no egg - just a dynamically evolving system that includes both the PDO and THC as well as many other factors. The 10,000 years was eyeballed from the Vostok ice core data. Temp changes either way of up to 10 degrees over a few thousand years. The Bermuda-Labrador Basin Transport Index is down since early this century - there is a nice collection of ocean/climate data at http://ioc-goos-oopc.org/state_of_the_ocean/sub/berm_lab_trans.php - and it is très amusant to speculate that early in 1998 might have been the warmest point in the next 100,000 years. It is overwhelmingly probable that an ice age is around the next climate corner. That gives me an idea - use autocorrelation minima (slowing down in complex systems theory) on the Vostok data to predict initiation of the next ice age. I may be gone for some time. On Dec 30, 2:32 am, Eric Swanson <[email protected]> wrote: > On Dec 28, 2:31 am, Robbo <[email protected]> wrote: > > > > > On Dec 28, 10:22 am, Eric Swanson <[email protected]> wrote: > > > > I must strongly disagree with what you wrote. > > > > On Dec 27, 4:22 pm, Robbo <[email protected]> wrote: > > > > > Temperatures peaked (in every record of monthly temperature anomalies) > > > > in the big El Nino of 1998. A wider significance of this is addressed > > > > in the Tsonis et al and Swanson and Tsonis papers referenced - a > > > > sudden climate shift in 1998/2001. Climate seen as a nonlinear > > > > oscillator - a complex system in chaos theory. It seems possible that > > > > the current cool mode will persist for another decade or two - until > > > > the next multidecadal climate shift. New and startling science I know > > > > - but as implacably logical as the Special Theory of > > > > Relativity. > > > > There's another situation which may have impacted the climate of the > > > late 1970's. It was called The Great Salinity Anomaly and was a large > > > pool of relatively fresh water which circulated around the North > > > Atlantic Sub Polar Gyre. About the same time, measurements indicated > > > that the formation of bottom water in the Greenland Sea had ceased. > > > That's like what may happen if the Thermohaline Circulation (THC) were > > > to weaken or stop and most climate models coupled to dynamic ocean > > > models predict that the THC will stop as the climate warms. > > > >http://www.whoi.edu/oceanus/viewArticle.do?id=2344&archives=true > > > You complain about Christy in 2003 - but use a 1996 (non peer > > reviwed?) article on THC. If you had looked at the peer reviewed > > science I referenced you would know that climate shifts - mini climate > > tipping points - occur when global ocean states synchonise and then > > shift into a different state. > > > THC is one of many nonlinear components of climate that has the > > potential tobite us on the bum. > > I complained about your use of Christy's old PR data. You ignored the > fact that his latest data shows more warming. You commented about the > recent work from Swanson and Tsonis regarding the so-called Pacific > Decadal Oscillation and I pointed out that the Pacific is linked to > the North Atlantic thru the THC. The analysis of Swanson and Tsonis > is rather speculative and based on correlations. As anyone in science > knows, correlation is not causation. > > > > One area in the Western Greenland Sea has exhibited changes associated > > > with a reduction in THC in that area for the past two winters. The > > > same pattern appears to be repeating so far this winter. Note the > > > suggestion that the GSA was the result of increased flow of sea-ice > > > out of the Arctic in 1967. That outflow has happened again these past > > > few years. Only this time, it may not stop if the Arctic sea-ice > > > melts away and opens the floodgates... > > > Short term characterisation of ocean elements that have obvious > > decadal variability. THC in the Atlantic is one of those elements > > that may result in an extreme nonlinear climate shift - morphing into > > ice growth and an ice age over the next 10,000 years. Interesting - > > but what do you want me to do about it? I already agree that we > > should stop destabilising climate. > > Again, the change to Ice Age conditions may happen much sooner than > your projected 10,000 years. At the start of the present period of > Ice Ages some 3 million years BP, it appears that the North Atlantic > and the Arctic were much warmer than today. It's easy to speculate > that our increasingly warm conditions could bring on another period of > very cold conditions, i.e., a return of a real Ice Age. > > http://micropress.org/stratigraphy/papers/Stratigraphy_6_4_265-275.pdf > > > > > > > The current temperature trend is flat but any trend is masked by large > > > > interannual variation mostly due to ENSO - making it impossible to be > > > > definitive especially over shorter periods. Over longer periods of 50 > > > > or more years - the trend is about 0.1 degrees centigrade/decade. > > > > Using the period of recent warming - 1976 to 1998 - includes two > > > > periods of large climate fluctuation - the 1976/1977 'Great Pacific > > > > Climate Shift' and the 1998/2001 climate shift - and distorts the true > > > > rising trend. The other reference I cited was Thompson et al - who > > > > filtered ENSO, volcanos and 'dynamically induced variability' from the > > > > record. Reasonable estimates of the recent trend are about 0.1 > > > > degrees/decade. > > > > See above. The PDO may be associated with changes in the THC in the > > > North Atlantic. > > > As above - the PDO and the IPO (Interdecadal Pacific Oscillation - a > > Pacific wide phenomenon) - are probably an emergent global property of > > climate as a dynamically variable complex system. > > We know the THC varies and I pointed to data that showed it weakened > considerably during the 1970's. The PDO variations may not explain > the temperature changes, both may be caused by some other aspect of > climate. I think it's just as reasonable to conclude that the > oscillations in the PDO may have been the result of changes in the > THC. Chicken or Egg, anyone? > > E. S. > ---- -- 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
