Darwin’s discovery of evolution by natural selection (and independently by Wallace) was the result of many years of meticulous observations of the natural world. In some ways it was even more brilliant because this discovery was made in the absence of any known basis for the variations in species (which are ultimately required by the theory).
It took a century to pass, with the discovery of DNA’s structure and processes, for scientists to understand how the shuffling and transposition of genes provided the underlying mechanism for the variations on which natural selection depends (along with the differentiation of environments that provides the selective pressures at the level of species).
While there continues to be a rich vein of discoveries in the exploration of this interplay between the genotype and phenotype, the underlying truth of Darwinian natural selection remains inviolate.
Similarly, through the statistical analysis of lung cancer rates, the link between smoking and lung cancer was clearly demonstrated in 1962 (Royal College of Physician’s report ‘Smoking and Health’), long before the underlying causative processes were understood (and these underlying processes could be argued to be very much still ‘work in progress’). No one seriously doubts the link, even though the tobacco industry tried for many years to claim that correlation does not prove causation.
In the case of man-made global warming (or ‘anthropogenic global warming’, AGW), the history of its discovery is in complete contrast to the above examples. With AGW we knew the essential underlying mechanism before, not after, the macro-scale phenomenon was even recognised as an issue!
By 1861, Tyndall’s experiments had demonstrated unequivocally that carbon dioxide was able to trap heat, and in 1896 Arrhenius had made the first calculations (laboriously by hand) of how variations in the concentration of carbon dioxide in the atmosphere would impact average global temperature.
Yet despite this, it took till 1938 before Callendar first published data to show that far from being a theoretical possibility, man’s emissions of carbon dioxide were indeed having a measurable influence on global average temperature.
Few scientists took this up as an issue at this time, or even as a research priority. Maybe in 1938 the world had some higher priorities to address, with the world already deep into the ‘dark valley’ and on the eve of World War II, but it is certainly true that there was not much interest in the topic even in academic circles.
Of course, over the years some did explore different aspects related to climate and related fields of enquiry, such as the study of glaciers, diverse isotopic methods, modelling weather and climate, and many more, but these were distinct fields which did not really converse with each other. It was really only in the 1970s that various seminal conferences took place that tried to piece together these disparate strands of evidence. This history is explored in meticulous detail in Weart’s ‘The Discovery of Global Warming’
Perhaps the most striking was the use of isotopes of oxygen measured in ice cores, acting as a proxy for temperature (because of the differential evaporation rates of water), which correlated strikingly with CO2 concentrations. As Weart notes:
“In the 1960s, painstaking studies had shown that subtle shifts in our planet’s orbit around the Sun (called “Milankovitch cycles”) matched the timing of ice ages with startling precision. The amount of sunlight that fell in a given latitude and season varied predictably over millenia. …
The new ice cores suggested that a powerful feedback amplified the changes in sunlight.
The crucial fact was that a slight warming would cause the level of greenhouse gases to rise slightly. For one thing, warmer oceans would evaporate out more gas. For another, as the vast Arctic tundras warmed up, the bogs would emit more CO2 (and another greenhouse gas, methane, also measured in the ice with a lag behind temperature). The greenhouse effect of these gases would raise the temperature a little more, which would cause more emission of gases, which would … and so forth, hauling the planet step by step into a warm period.
Many thousands of years later, the process would reverse when the sunlight falling in key latitudes weakened. Bogs and oceans would absorb greenhouse gases, ice would build up, and the planet would slide back into an ice age. This finally explained how tiny shifts in the Earth’s orbit could set the timing of the enormous swings of glacial cycles.”
These ice cores and associated methods were improved over several decades with the Vostok cores reaching back 400,000 years finally convincing many in the scientific community.
Only in the 1980s was AGW finally gaining recognition as a serious issue, and this led eventually to the formation of the IPCC in 1988, which is the internationally sponsored vehicle for assembling, reviewing and reporting on the multiple primary published research including interlocking streams of evidence and analysis.
There are some who argue against the much vaunted consensus on AGW (the 97% of climate scientists who agree that AGW is demonstrated).
I was at a meeting recently on science communication where someone from the audience objected to this 97% consensus saying “can we trust a science where so many are in agreement?” … he was pointing out that often in science there is a hotbed of debate and disagreement. Surely this 97% is evidence of some kind of group-think?
Well, of course, as Weart documents, at almost every step in the 200 odd years of science that has tried to explain the ice ages, and latterly global warming, there has been intense scientific dialogue that has been a million miles from group-think. The role of Milanovitch cycles, mentioned in the above quote, is just one example. The dialogue continues, for example, in relation to the so-called ‘hiatus’ and many other topics.
But these same combative scientists do not dispute the reality of AGW only the details, and particularly those relating to regional impacts. These will of course be the subject of intense research that continues as we as humans seek to mitigate where we can, and adapt where we must.
Let’s consider some possible examples of ‘group think’ in science:
- Ask 1000 biologists if they think Darwinian natural selection is true and I suggest over 97% would concur.
- Ask 1000 clinicians if smoking will greatly increase the risk of lung cancer and I suggest over 97% would concur.
- Ask 1000 physicists if they think the 2nd Law of Thermodynamics is both true, and will survive any revolution in science (even the changes that dark matter and energy no doubt presages), and I suggest that over 97% would concur.
Are these examples of ‘group-think’?
I would say, absolutely not! They represent a consensus informed by many decades of cumulative scientific endeavour that has stood the test of time and battled through many challenges and tests.
As we see from Weart’s history, the acceptance of AGW is not something the scientific community have jumped to in some rash, rush to agree; that’s not how science works. Rather, it has been a methodical, multi-disciplinary emergence of an understanding over many decades, which only quite recently (1980s) can be said to have reached a consensus.
The reality of AGW has survived many challenges and tests (mostly from within the scientific community, best able to frame challenging tests).
I think it is therefore a rather lazy and ill-informed viewpoint to characterise the consensus on AGW among scientists (and specifically climate scientists) as evidence of ‘group-think’.
Perhaps those determined to disagree with AGW should ask themselves whether in fact they are the real victims of ‘group-think’: a curmudgeonly kind of contrarian group-think from an increasingly marginalised section of the media.
EssaysConcerning 