Perception Is Not a Science

Is your summer warmer than normal, or did your winter seem colder than in the past? We may perceive changes in weather patterns and draw conclusions, but personal experience is of limited value in science. It’s all about the data.

Dr. James Hansen, a senior NASA scientist and long-time global warming apologist, first achieved notoriety when he testified before Congress in 1988 about what he described as the catastrophic effects of anthropogenic climate change expected within the next 20 years. His testimony was based on computer projections using atmospheric concentrations of CO₂ to determine ambient temperatures. In retrospect, his predictions were wildly exaggerated.

Failed Logic Leap

Hansen has since slowly devolved from space scientist into space cadet and has become an embarrassment to NASA. On Aug. 6, Hansen released the paper “Perceptions of Climate Change” in the Proceeding of the National Academy of Sciences (PNAS). The National Academy of Sciences continues to “peer review” his work with a wink and a nod. The article purports to prove that “recent heat waves and extreme summers were likely caused by global warming in recent high profile heat waves, such as those in Texas and Oklahoma in the summer of 2011.” The data used to make the comparison and draw conclusions is limited to June, July, and August surface temperatures relative to a base period of 1951–1980, a period of relatively stable temperatures.

The analysis approach used by Hansen was to plot temperature observations as a bell curve, much like the sort that some teachers use to grade student work. The small percentage of students who earn an A are equivalent to “extremely hot” events. Hansen suggests that because the number of reported temperatures over the past 30 years fall with higher frequency in the “extremely hot” category compared to the base period, anthropogenic CO₂ emissions are to blame.

Hansen next “proves” the link between specific weather events and global warming in a most unscientific way, as the title of the paper implies: the proof is left to the reader’s perception. If climate change (average annual temperatures) doesn’t explain weather patterns, then what else could it be? As Dr. Martin Hoerling, a researcher with the National Oceanic and Atmospheric Administration (NOAA), noted in his review of Hansen’s paper, “Perception is not a science.”

Most appalling was Hansen’s use of “cherry picked” data that ignored temperature data from the warmer 1930s and the cooler 2000s that would have significantly altered his results. The shape of the bell curve flattens and widens at the bottom if an entire 100 years of temperature data are used, effectively quashing Hansen’s entire analysis. There are many other technical gaffes in Hansen’s analysis, like simplistically equating heat waves with droughts, but space prevents further discussion.

Hard Data Results

Dr. John Christy, distinguished professor of atmospheric science and director of the Earth System Science Center at the University of Alabama in Huntsville presented testimony on Aug. 1 to the Senate Environment and Public Works Committee about extreme temperature events. Dr. Christy’s expertise is remote satellite sensing of atmospheric temperatures. His conclusion, when studying the entire temperature data set, was that the data does not prove weather is becoming less extreme or colder but rather that “extreme events are poor metrics to use for detecting climate change.”

In his testimony, Dr. Christy noted that the 1930s temperature data set has twice as many daily maximum temperature records as the 1980s, 1990s, or 2000s; daily all-time high temperatures occurred more frequently before 1940 than after 1954; and more Midwest daily maximum temperature records were set in the heat waves of 1911 and the 1930s (the Dust Bowl era) than during the 2012 heat wave. Statistically, in any 100-year period, we should expect 10% of the worst temperature extremes to occur during any particular decade.

Christy also addressed other perceived effects of climate change. For example, the Palmer Drought Severity Index for the continental U.S. shows considerable interannual variability but shows no long-term trend from 1900 to the present, and the upper Colorado River Basin experienced more frequent multi-decadal droughts in the 19th, 18th, 17th, and 16th centuries than in the 20th century. Also, NOAA’s Climate Scene Investigators concluded that recent record snowfalls were not caused by human activity. In fact, the historical analysis found no evidence of any increase in snowfall.

True Motives Revealed

Hansen writes in his paper, “Although we were motivated in this research by an objective to expose effects of human-made global warming as soon as possible…” By his own words, Hansen has assumed the role of activist masquerading as a scientist. NASA continues to ignore the proclivities of its rogue scientist and refuses to rein him in.

One of NASA’s few recent achievements occurred during the early morning of Aug. 6, when the Mars Science Laboratory rover Curiosity successfully descended to the planet’s surface and began sending images back to Earth. The rover’s two-year plan includes studying the Martian climate and geology in preparation for a future manned mission.

Hansen carefully scripted the release of the paper for Aug. 6 to coincide with the nation’s celebration of Curiosity’ s successful landing. Bad science may be forgivable, but I suspect Hansen’s attempt to hijack the media spotlight from one of NASA’s few recent space triumphs is the NASA equivalent of the unpardonable sin.

— Dr. Robert Peltier, PE is POWER’s editor-in-chief.