The Daily Mail (UK) has reported on a study by Ross McKitrick of the University of Guelph in Canada that, yet again, resurrects the tired old “warming pause” meme. Climate Nexus notes that the study uses data endpoints specifically chosen to show no trend; ignores a large body of contradictory scientific evidence; and was published in a journal known to be a “predatory publisher.” McKitrick, a well-known antagonist to mainstream climate scientists, is using bad analysis to reach a pre-determined conclusion.
The following is a guest post from Climate Nexus (text in PDF format here):
Daily Mail Touts Study Using Cherry-Picked Data
to Question Climate Change
The Daily Mail (UK) has reported on a study by Ross McKitrick of the University of Guelph in Canada that, yet again, resurrects the tired old “warming pause” meme. The study looks at the change in average global temperatures over a narrow timeframe, and admits to “cherry-picking of endpoints” for the temperature data it analyzes. This is problematic in that short-term variability can affect the trend. For example, studies confirm that the oceans are absorbing an increased amount of heat, allowing surface temperatures to level off temporarily. Scientists agree that over the past 50 years, global temperatures have been rising due to human activity, and this rise is projected to continue.
- The study uses data endpoints specifically chosen to show no trend.
- The study ignores a large body of contradictory scientific evidence.
- The study was published in a journal known to be a “predatory publisher.”
The study cherry-picks data and makes trend observations that are not meaningful.
The study is not statistically rigorous, in that it simply uses a single starting point near the present, and works backwards in time to test if the sample period shows a trend. This doesn’t make a lot of sense as a way to test the accuracy of climate models, which are built to function on far longer timescales. It also isn’t even an effective way to prove a lack of trend. For example, the trend for the period McKitrick highlights is not quite statistically significant, but the confidence interval shows it is equally likely to be 0.19 ºC of warming per decade, as it is to be 0 ºC. That’s not the same as proving no trend.
One blogger even tried the same technique using simulated data that DID have a constant trend, and found that in 10% of cases McKitrick’s methods would still have shown a pause starting in 1995 or before.
The study ignores previous evidence showing that the pause may be exaggerated.
For example, Cowtan and Way found that significant under-sampling of the Arctic in the modern temperature record may have given a low bias to recent global average temperatures. If they are correct, the slowdown in surface warming may be half of what the HadCRUT data series (which McKitrick uses) shows.
There are also many contributors to the surface warming slowdown that are still consistent with long-term human-caused warming. One big factor is the deep oceans’ submergence of heat, which new research shows has increased in recent years (in both the Pacific and Atlantic). History tells us that this uptake is likely to eventually reverse, in turn causing surface warming to accelerate once again. Surface and ocean temperatures may seesaw, but the overall global temperature trend remains upward.
The journal that published McKitrick’s study is on a list of “predatory publishers.”
The number of predatory publishershas skyrocketed in recent years, growing from 18 in 2011 to 477 in 2014. These publishers rely on an open-access model in which authors pay the journal for publication, a process that critics say leads to corruptionand a lack of peer-review. The “Open Journal of Statistics” published the McKitrick study, and is under the Scientific Research Publishing imprint which appears on lists of predatory publishers.
McKitrick doesn’t have a pristine scientific record either. One of his most blatant mistakes was to measure angles in degrees instead of radians, a basic and extremely important distinction in units of measurement. He is also a well-known antagonist to mainstream climate scientists, inserting himself into the “Climategate” controversy in 2010 by alleging that scientists were “faking the match” between proxy and temperature data.
McKitrick’s study seeks to perpetuate a meme that has been refuted over and over. It uses poorly developed statistical techniques to prop up a pre-determined goal.
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