Flash Point: Hot It’s Not – Get Your Bias Right

Today we became aware of an academic paper by Dr. Ross McKitrick, an economist and statistician specializing in environmental science, titled HAC-Robust Measurement of the Duration of a Trendless Subsample in a Global Climate Time Series. (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.) From the abstract (emphasis ours): The IPCC has drawn attention to an apparent leveling-off of globally-averaged temperatures over the past 15 years or so. Measuring the duration of the hiatus -- Application of the method [described in the abstract but technically complex] shows that there is now a trendless interval of 19 years duration at the end of the HadCRUT4 surface temperature series, and of 16 – 26 years in the lower troposphere.

In other words, temperatures have not increased at the planet's surface for the last 19 years (since 1995). In the lowest layer of the atmosphere (the troposphere) the "hiatus"; – the term widely used to identify this period – may extend to 26 years. This is one of the principal data sets used by climatologists in building climate models. McKitrick's analysis and conclusions may only be challenged by persons able to understand his premises and follow his calculations. Few will be qualified to do this. So folks, global warming is on hold, or as the community says, in hiatus.

The Common Bias

The bias we wish to point out is the assumption we are in a warming trend and one that man's activity will cause to rise catastrophically. It is not the idea of a hiatus that we have a problem with but the underlying assumption of trend that it is applied to. If we look at the cyclical record of glaciation revealed in the data from the Vostok ice core (see the chart in Obama Declares War on Global Warming) we may infer that we are just off an interglacial peak temperature and are at the start of a cooling trend. In the context of the roughly 100,000 year glaciation cycle the current period of so-called warming is statistical noise. Indeed, this was a cover of Time magazine in 1977: Source: The Omega Letter Commentary. Generally, everyone discusses global temperature change in the context of a warming trend. Maybe we should switch back to the context of a cooling trend that the Time article was framed in terms of. At the least we should recognize we have a bias and that we are not trend neutral.