Dette fremgår i en nylig utkommet artikkel fra McKitrick & Vogelsong:
HAC robust trend comparisons among climateseries with possible level shifts
Og legg merke til, forfatterne mener at denne artikkelen er så viktig at alle skal få lese den. Det er langt mellom hver Open Access i klimasammenheng!
Fra Abstractet sakser jeg:
“Our application builds on the literature comparing simulated and observed trends in the tropical lowertroposphere and mid-troposphere since 1958. The method identifies a shift in observations around 1977, coinciding with thePacific Climate Shift. Allowing for a level shift causes apparently significant observed trends to become statistically insignificant. Model overestimation of warming is significant whether or not we account for a level shift, although null rejections are much stronger when the level shift is included.”
Fra Conclusion sakser jeg:
“As our empirical findings show, the detection of a trend in the tropical lower troposphere and mid-troposphere data over the 1958–2012interval is contingent on the decision of whether or not to control for a level shift coinciding with the PCS. If the term is included, a timetrend regression with autocorrelation-robust error terms indicates that the trend is small and not statistically different from zero in eitherthe LT or MT layers. Also, most climate models predict a significantly larger trend over this interval than is observed in either layer. Wefind a statistically significant discrepancy between the average climate model trend and observational trends whether or not the mean-shift term is included. However, with the shift term included, the null hypothesis of trend equivalence is rejected much more strongly (at muchsmaller significance levels).”
Det er visst ingen ende på elendighetene til Klimamodellene.