The Current Wisdom is a series of monthly articles in which Patrick J. Michaels and Paul C. “Chip” Knappenberger, from Cato’s Center for the Study of Science, review interesting items on global warming in the scientific literature or of a more technical nature. These items may not have received the media attention that they deserved or have been misinterpreted in the popular press.
Posted Wednesday in the Washington Post’s new online “Energy and Environment” section is a piece titled “No, Climate Models Aren’t Exaggerating Global Warming.” That’s a pretty “out there” headline considering all the evidence to the contrary.
We summed up much of the contrary evidence in a presentation at the annual meeting of the American Geophysical Union last December. The take-home message—that climate models were on the verge of failure (basically the opposite of the Post headline)—is self-evident in Figure 1, adapted from our presentation.
Figure 1. Comparison of observed trends (colored circles according to legend) with the climate model trends (black circles) for periods from 10 to 64 years in length. All trends end with data from the year 2014 (adapted from Michaels and Knappenberger, 2014).
The figure shows (with colored circles) the value of the trend in observed global average surface temperatures in lengths ranging from 10 to 64 years and in all cases ending in 2014 (the so-called “warmest year on record”). Also included in the figure (black circles) is the average trend in surface temperatures produced by a collection of climate models for the same intervals. For example, for the period 1951–2014 (the leftmost points in the chart, representing a trend length of 64 years) the trend in the observations is 0.11°C per decade and the average model projected trend is 0.15°C per decade. During the most recent 10-year period (2005–2014, rightmost points in the chart), the observed trend is 0.01°C per decade while the model trend is 0.21°C per decade.