To the Editor:
In the Fall 2016 Academic Questions (vol. 29, no. 3), Peter Wood’s “Books, Articles, and Items of Academic Interest” includes a section entitled “Sustainability.” In it, he references an article from the Science website: “Earth’s climate may not warm as quickly as expected, suggest new cloud studies.” The authors of this article suggest that Earth was perhaps cloudier in the past than originally thought, which in turn implies that the cooling effect of clouds―which reflect sunlight back into space―is not so different now than it was then. The upshot is that global warming may not be as sensitive to rising carbon dioxide levels as usually believed. Wood’s conclusion: “the ‘consensus’ climate models have wildly inflated possible global warming resulting from man-made pollution.” In the last paragraph of the article itself, Urs Baltensperger (one of the authors of the original papers, who was being interviewed), says, “[C]urrent best estimates of future temperature rises are still feasible, but ‘the highest values become improbable.’” Since these estimates are based, in part, on the effects of CO2 added to the atmosphere by humans, it is not clear to me how Dr. Wood got from “current best estimates of future temperature rises are still feasible,” to “‘consensus’ climate models have wildly inflated [the effect of] man-made pollution.”
In the next paragraph, Dr. Wood references another article: “Making Sense of the Early-2000s Warming Slowdown” (J.C. Fyfe et al., Nature Climate Change, vol. 6, March 2016, 224–28). Here, the authors take issue with an earlier study published in Science (Thomas R. Karl et al., “Possible Artifacts of Data Biases in the Recent Global Surface Warming Hiatus,” vol. 348, June 26, 2015, 1469–72). According to Wood, Karl et al. “tried to erase the near absence of global warming over the past eighteen years…by artificially resetting older ocean temperatures to make the planet seem cooler in the last century.” In fact, what Karl et al. were attempting to do was correct for earlier measurement biases (going back to around World War II), based on a better understanding of how different methods of measurement produce slightly different results. There’s nothing inherently “artificial” about trying to do this. As can be seen in one of the graphs in their paper, a series of corrections have demonstrated that the period from the late nineteenth to early twentieth century was a bit warmer than the contemporary measurements indicated, meaning global warming since then has been slightly smaller than the original data suggested; it therefore seems unlikely that this “correction process” is intended to make things look worse than they really are. Nowhere in the Fyfe et al. article is there any suggestion of a “problem” with Karl et al.’s corrected data―in fact, it’s presented as a graph in “Making Sense” without comment. What Fyfe et al. “repudiate” is the inclusion of data from the 1950s through 1970s (the “big hiatus”) in the baseline for comparison to more recent trends. They assert (properly, in my opinion) that it makes better sense to compare twenty-first-century measurements with more recent temperature records, from the early 1970s up to about 2000.
James H. Taylor
Associate Professor of Physics
University of Central Missouri
Response to Prof. Taylor
Editor’s note: Dr. Wood invited William Happer to reply on his behalf.
Dr. Wood’s statement, “the ‘consensus’ climate models have wildly inflated possible global warming resulting from man-made pollution,” could perhaps have been worded more carefully, since one would naturally assume that the “man-made pollution” Dr. Wood refers to is carbon dioxide, CO2. Huge amounts of the “pollutant” CO2 are released to the atmosphere due to respiration of living things—from microorganisms to humans. Human activities, most notably the combustion of fossil fuels, add a relatively small amount to this natural release of CO2. Nearly equal amounts of CO2 are absorbed from the atmosphere by photosynthetic living organisms on the land and in the oceans. Also, each human exhales about two pounds of the “pollutant” CO2 per day. The Earth’s 7.5 billion people therefore release 7.5 million tons of CO2 per day, an impressive “carbon footprint.” No wonder that many “saviors of the planet” want to reduce the human population dramatically, typically to around one billion people or less. Which of us is supposed to volunteer to vacate the Earth?
Fortunately, the alarmists are completely wrong. CO2 is not a pollutant, but a benefit to the Earth. Current CO2 concentrations in the atmosphere, about 400 parts per million (ppm), are much less than the several thousand ppm that prevailed over most of the geological history of the Earth. As far as plants are concerned, the Earth has been in a CO2 famine for tens of millions of years. Green plants are responding to increased CO2 levels with more vigorous growth, especially in arid regions of the globe. All plants grow better with more CO2, and especially “C3 plants,” which account for most agricultural crops, wheat, soybeans, rice, cotton, etc. But Dr. Wood’s main point, “climate models have wildly inflated possible global warming,” is fully supported by figure 1 from John C. Fyfe and his colleagues,1 one of the research groups Prof. Taylor cites.
Trends in global mean surface temperature. a, 1993–2012. b, 1998–2012. Histograms of observed trends (red hatching) are from 100 reconstructions of the HadCRUT4 dataset1. Histograms of model trends (grey bars) are based on 117 simulations of the models, and black curves are smoothed versions of the model trends. The ranges of observed trends reflect observational uncertainty, whereas the ranges of model trends reflect forcing uncertainty, as well as differences in individual model responses to external forcings and uncertainty arising from internal climate variability.Reprinted by permission from Macmillan Publishers Ltd: Nature Climate Change, John C. Fyfe, Nathan P. Gillett, Francis W. Zwiers, “Overestimated Global Warming over the Past 20 Years,” 3, 767–69 © 2013, doi:10.1038/nclimate1972, http://www.nature.com/nclimate/index.html.
Readers not used to seeing graphs should take a little time to study this important figure. The horizontal axis is labeled by warming per decade, and the gray bars are a histogram of the predicted warming by about 100 climate models. The cross-hatched bars (which appear in red in the online version of this letter) are the observed warmings. The panel on the left shows that the average predicted warming for the years 1993 to 2012 was about 0.3 °C/decade while the observed warming was about 0.14 °C/decade. So the models predicted a little more than twice as much warming than was observed, 100 percent too much warming.
The panel on the right shows the warming for the years 1998 to 2012, when chastened modelers had lowered their warming prediction to an average value of only 0.2 °C/decade, but when the observed warming also decreased dramatically, to only about 0.05 °C/decade. This near cessation of warming after 1998 is the celebrated “hiatus” mentioned by Prof. Taylor. After 1998 the models predicted about four times more warming than observed or 300 percent too much warming.
One hundred percent too much warming! Three hundred percent too much warming! What else can you call this if not “wildly inflated possible global warming”?
Cyrus Fogg Brackett Professor of Physics, Emeritus