Robert, The index to which you refer (the PEA) does not address the THC, only the surface and near-surface circulation, (as described in your quote), if I read it correctly.
> As for Atlantic currents the ‘transport index estimates the strength > of the baroclinic gyre circulation in the North Atlantic, or the > strength of the Gulf Stream and North Atlantic Current system. The > units (Mtons s-1) are within a few percent of the volumetric unit of > transport (Sverdrups = 106 m3s-1). It is calculated from the > difference of the potential energy anomalies (PEA) near Bermuda and in > the Labrador Basin (top two panels). [cut] > The NAO precedes the transport index by about a year – so expect > further decline in transport. This is an example – by the way – of > abrupt climate change on interaanual to decadal timescales. > > There is much better info on sea ice (and other things) from Prof Ole > Humlum – a glaciologist. > > http://www.climate4you.com/ > > ‘Based on these observational data, Polyakov et al. (2003) concluded > that the ‘examination of records of fast ice thickness and ice extent > from four Arctic marginal seas (Kara, Laptev, East Siberian, and > Chukchi) indicates that long-term trends are small and generally > statistically insignificant, while trends for shorter records are not > indicative of the long-term tendencies due to strong low-frequency > variability in these time series, which places a strong limitation on > our ability to resolve long-term trends’. Recent trends in Arctic sea-ice minimum at the end of the melt season are rather obviously negative. The decline appears to be occurring faster than the models' projections. http://s454.photobucket.com/albums/qq268/Know_body/?action=view¤t=sea-ice_ext.jpg > The key phrase is low frequency variability – again a decadal abrupt > shift – following closely from Arctic temperature and zonal SLP > changes and therefore also ocean salt and heat transport and deep > water formation. > > What does this mean for the future? Don’t look at me – I think we are > on the extreme warm climate ‘strange attractor.’ Much more likely to > shift to cooler mode. As much as a 10 degree cooling in a couple of > months to years is possible. What does this mean for the future? The Arctic sea-ice is melting. Must be getting warmer. 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
