To the editor:
I am pleased to be able to respond to the Boggses’ letter to The Gazette (“Global warming a ‘theory, not a proven fact’,” April 15). The headline obviously reflects the authors’ misunderstanding of what is fact and what is theory in science.
Facts are data. In some cases, such as satellite microwave measurements, these data must be adjusted for many factors, including change of time of day the satellite flies over some location, and analysis is done to try to extract a temperature (in other words, this is not like a direct thermometer temperature measurement). If, for example, there are errors in calibration, this invalidates the data that result. In other cases, data can be gathered directly. After the required maneuvers to obtain these data, they constitute facts.
Theories are the highest form of human expression of our (limited) understanding of how nature works. Theories are built from data. As the famed physicist Henri Poincaré has written, “Science is built of facts the way a house is built of bricks; but an accumulation of facts is no more science than a pile of bricks is a house.” Hypotheses string facts together in ways that lead to predictions that can be tested. After many tests by many scientists over many years, if the various hypotheses that are tied together have not been disproven, we can call the result a theory. Of course, it is possible that an accepted theory is eventually disproven, in which case scientists must construct a new theory. That is the case with gravitation, when Einstein’s General Theory of Relativity replaced Newton’s theory of universal gravitation.
As to the methodology of the 97 percent figure, a paper published this week in Environmental Research Letters by John Cook et al., “Consensus on consensus: a synthesis of consensus estimates on human-caused global warming,” finds that the more expert the person, the greater the likelihood that they are part of the 97 percent to 99.9 percent consensus among climate scientists that humans are responsible for the current planetary warming. They write: “We have shown that the scientific consensus on AGW (human-caused global warming) is robust, with a range of 90 percent-100 percent depending on the exact question, timing and sampling methodology. This is supported by multiple independent studies despite variations in the study timing, definition of consensus, or differences in methodology including surveys of scientists, analyses of literature or of citation networks. … From a broader perspective, it doesn’t matter if the consensus number is 90 percent or 100 percent. The level of scientific agreement on AGW is overwhelmingly high because the supporting evidence is overwhelmingly strong.”
As I point out above, there is always the possibility that the best science we have at present is wrong or incomplete. This means that consensus does not guarantee correctness. Indeed, any given scientist can be wrong, as is Professor (John) Christy when he says that the IPCC’s predictions were off by a factor of two. The claim is laughably false because IPCC predicts future temperature anomalies based on many differing emissions models. Depending on what emissions model is used, a future temperature is predicted. IPCC quotes a range of temperatures coming from the group of emissions models and, going back to the first IPCC report, the current temperature anomaly is within that predicted range. I cannot determine what Professor Christy was referring to in his assertion.
Finally, in any case, it is a position of the Heritage Foundation (a denialist organization that receives a huge amount of funding from oil companies) that is being quoted without attribution in the Boggses’ letter, a position that ignores that 2015, 2014, 2010, 2005 and 2013 — in that order — are the world’s warmest years since at least 1880 and very likely since 1000 B.C. and that the months of December, January, February and March have all successively set global temperature records.
— Gordon Aubrecht
Delaware
