Monday, December 10th 2012, 5:40 PM EST
The apparent leveling of the global temperature time series at the end of the 1990s may represent a break in the upward trend. A study of the time series measurements for temperature, carbon dioxide, humidity and methane shows changes coincident with phase changes of the Atlantic and Pacific Decadal Oscillations. There are changes in carbon dioxide, humidity and methane measurement series in 2000. If these changes mark a phase change of the Pacific Decadal Oscillation then it might explain the global temperature behaviour
The apparent leveling of the global temperature time series(Brohan et al., 2006) at the end of the 1990s may represent a break in the upward trend. But the methodology is widely disputed. For example in a long editorial comment in the journal Climate Change, Terence Mills (Mills, 2010), a UK econometrician who has written at length on temperature trend analysis, concludes that “Statistical arguments alone are unlikely to settle issues such as these, but neither are appeals to only physical models or the output of computer simulations of coupled general circulation models….it is a case of you pays your money and you takes your choice”.
The approach adopted here is to look at the time development of global temperature and other atmospheric variables to see if there is supporting evidence of a significant change.
Further the Great Pacific Climate Shift (GPCS) (Mantua et al., 1997) of 1976-77 a part of the Pacific Decadal Oscillation (PDO) and the identification of a phase change in the Atlantic Decadal Oscillation (ADO) related to changes in the concentration of atmospheric CO2 (Wang and Dong, 2010), may offer a test bed of global indicators for the late 1990s. Thus atmospheric carbon dioxide (CO2), humidity and atmospheric methane are examined below using the Chow Break Test (Chow, 1960).
Click source to download paper in FULL from Tom Quirk
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