Professor Hansen came across as a scientifically minded Inspector Poirot, assembling the family in the library to explain how the murderer among them had hidden his crime. But within ten years, he had morphed into the hapless Inspector Clouseau. His own NASA weather satellites — the most accurate barometers of global temperature — showed that, despite his eschatological forecast, the Earth had warmed very little.
So little, in fact, that Hansen retracted his prediction in 1998, conceding that he’d failed to take into account that forests, the soil, and the ocean absorb significant amounts of carbon dioxide. “The forces that drive long-term climate change are not known with accuracy sufficient to define future climate change,” he acknowledged. In 2001, his U-turn was complete: Far from the ten degrees of change predicted, global temperatures would now rise by 0.7 degrees Fahrenheit, he wrote. Thus, the man who once urged an unimpressed Reagan administration to do its bit to “save the world” now stood against Kyoto because “it targets the wrong gas.”
There is nothing wrong with a scientist repeatedly changing his mind — that is part of the game — nor should America’s researchers apologize for repeatedly altering their predictions as new evidence comes to light. In fact, given the sheer size of the issue, such movement is inevitable. But it all gets rather tricky when massive government programs are promoted and adopted on the back of inconclusive evidence, and it gets especially tricky when the imprimatur of a well-respected organization such as NASA is dragged into the fray and deployed to lend unassailable credibility to nascent and unproven ideas. It is one thing for a scientist to cook up ideas with abandon, but quite another to do so with the papers stamped by the government.
In the words of this week’s strongly worded letter from 49 former NASA scientists and astronauts, publicizing the trial-and-error process in this way does “damage to the exemplary reputation of NASA, NASA’s current or former scientists and employees, and even the reputation of science itself.” When any respected organization takes “an extreme position” and includes “unproven and unsupported remarks” in its public utterances, it is gambling recklessly with fate — and the stakes in this gamble, it turns out, have often been described by Hansen in terms rather unsuitable for the head of a government agency, especially when the topic is as vast and uncharted as climate science. Yet, in 2006, Hansen called climate change “a moral issue on a par with slavery,” labeled coal trains “death trains,” and asserted that they would be “no less gruesome than if they were boxcars headed to crematoria, loaded with uncountable irreplaceable species.” Continuing the drama, Hansen was arrested last summer outside the White House for protesting the Keystone XL pipeline. It is unsurprising that many at NASA have criticized “ the GISS leadership” for overconfident pronouncements when, they point out, “the science is NOT settled.”
In response to such criticism, Hansen has often complained he’s been censored, noting that staff reviewed his work after an inflammatory lecture at the American Geophysical Union in San Francisco. But he appears not to grasp that having a platform such as GISS requires that you assume a corporate editorial responsibility. Nor does he see that government employment entails an implicit obligation to err on the side of caution. This, and not Hansen’s various scientific conclusions, is why New York Times columnist Andrew Revkin — who agrees with Hansen on the scientific questions — complained that “Dr. Hansen has pushed far beyond the boundaries of the conventional role of scientists, particularly government scientists, in the environmental policy debate” and why many more of those on his side of the fence seem to worry about his proclivities.
If this week’s letter from 49 former NASA scientists to the agency’s current head does nothing else, it should put paid to the popular lie that only rubes and antiscience types could possibly continue to question what is allegedly settled science. The world around us is extremely complex and our understanding of it limited. Professor Hansen is undoubtedly a talented scientist, and he is entitled to his conclusions; but it would behoove both his agency and his colleagues if he showed a little modesty. NASA’s reputation depends upon it.