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The IPCC has drawn attention to an apparentleveling-off of globally-averaged temperatures over the past 15 years or so.Measuring the duration of the hiatus has implications for determining if theunderlying trend has changed, and for evaluating climate models. Here, Ipropose a method for estimating the duration of the hiatus that is robust tounknown forms of heteroskedasticity and autocorrelation HAC in thetemperature series and to cherry-picking of endpoints. For the specific case ofglobal average temperatures I also add the requirement of spatial consistency betweenhemispheres. The method makes use of the Vogelsang-Franses 2005 HAC-robusttrend variance estimator which is valid as long as the underlying series istrend stationary, which is the case for the data used herein. Application ofthe method shows that there is now a trendless interval of 19 years duration atthe end of the HadCRUT4 surface temperature series, and of 16 - 26 years in thelower troposphere. Use of a simple AR1 trend model suggests a shorter hiatus of14 - 20 years but is likely unreliable.

KEYWORDS

Global Warming, Trend, HAC-Robust, Trendless Subsample

Cite this paper

McKitrick, R. 2014 HAC-Robust Measurement of the Duration of a Trendless Subsample in a Global Climate Time Series. Open Journal of Statistics, 4, 527-535. doi: 10.4236-ojs.2014.47050.





Author: Ross R. McKitrick

Source: http://www.scirp.org/



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