Karl et al ‘Pause-buster’ Paper Debunked Again

In June 2015, NOAA NCEI Director Thomas R. Karl published a paper “Possible artifacts of data biases in the recent global surface warming hiatus” that concludes

Here we present an updated global surface temperature analysis that reveals that global trends are higher than reported by the IPCC, especially in recent decades, and that the central estimate for the rate of warming during the first 15 years of the 21st century is at least as great as the last half of the 20th century. These results do not support the notion of a “slowdown” in the increase of global surface temperature.

In addition to the several problems with the questionable data adjustments made by Karl et al that have been thoroughly documented and analyzed by Bob Tisdale, Anthony Watts, Judith Curry, Richard S. Lindzen, Arno Arrak, Ross McKitrick, Patrick J. Michaels, Paul C. Knappenberger, Christopher Monckton of Brenchley, S. Fred Singer, and others in the following articles to name a few:

Sheldon Walker has published a stunningly simple and brilliant analysis that blows a gaping whole in Karl’s outlier conclusions, and it succeeds in doing so even while using Karl’s highly questionable data-warming adjustments—which were nearly instantaneously incorporated into several of the alarmist-managed datasets around the world (NOAA, NASA, and others) in time for the Paris affair. Walker uses a very illustrative scatter plot graphing technique showing all temperature trends of various lengths.


The gist of Karl et al is that the decadal warming rate from 1950 to 1999 (using their cooked data) of 0.113ºC is nearly identical to the rate of 0.116ºC from 2000 to 2014, and therefore there is no pause. The problem with this simplistic argument is that these are cherry-picked endpoints for trend analysis, and the anthropogenic warming rate was by no means constant during this period. Indeed, from 1950 to 1974, there was very little anthropogenic warming, whereas from 1975 to 1999 there was significant anthropogenic warming. By erroneously conflating those two very different time periods, Karl et al  concludes there is no ‘pause’ or ‘slowdown’. In fact, when one looks at the trends in decadal temperature change from 1975 to 1999 versus 2000 to 2014 even using Karl’s cooked data, there is a substantial slowdown aka hiatus aka pause.

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