There seems to be a lot of discussion about an apparently simple question:
Can science be ‘certain’ about, well, anything?
If that meant not doing anything – not building a bridge; not releasing a new drug; not taking off for the flight to New York; not flying a spacecraft to Saturn; not vaccinating the whole world against polio; not taking action to decarbonise our energy supply; Etc. – then this lack of 100% certainty might totally debilitate a modern society, frozen with doubt and so unable to act.
But of course, we do not stop implementing solutions based on our current best knowledge of nature and the world, however limited it might be. We make judgments. We assess risks. We weigh the evidence. We act.
I think scientists often fall into the trap of answering a quite different question:
Do we have a complete and all encompassing theory of the world (or at least, ‘this’ bit of the world, say how black holes work or how evolution played out)?
And everyone will rush defensively to the obvious answer, “no”. Why? Because we can always learn more, we can always improve, and indeed sometimes – although surprisingly rarely – we can make radical departures from received bodies of knowledge.
We are almost 100% certain of the ‘Second Law of Thermodynamics’ and Darwin’s ‘Evolution by Natural Selection’, but almost everything else is of a lower order.
But even when we do make radical departures, it doesn’t always mean a complete eradication of prior knowledge. It does when moving from superstition, religious dogma, witch-doctoring and superstitious theories of illness: as when we move to the germ theory of disease and a modern understanding biology, because people get cured, and ignorance is vanquished.
But take Newtonian mechanics. This remains valid for the not too small (quantum mechanical) and not too massive or fast (relativistic) domains of nature, and so remains a perfectly good approximation for understanding snooker balls, the motion of the solar system, and even the motion of fluids.
In the following Figure, from her entertaining TEDxManchester talk The fascinating physics of everyday life, she shows how the physics of the every day applies over a huge range of scales (in time and space); bracketed between the exotic worlds of the extremely small (quantum mechanics) and extremely large (general relativity) which tend to dominate our cultural perceptions of physics today.
Want to build a bridge, or build a solar system, or understand Saturn’s rings? Move over Schrodinger and Einstein, come on board Newton!
And yes, if you want to understand the interaction of molecules? Thank you Schrodinger.
Want to predict gravitational waves from a distant galaxy where two neutron stars are collinding? Thank you Einstein.
That is why the oft promulgated narrative of science – the periodic obliteration of old theories to be replaced by new ones – is often not quite how things work in practice. Instead of a vision of a singular pyramid of knowledge that is torn down when someone of Einstein’s genius comes along and rips away its foundations, one instead sees new independent pyramids popping up in the desert of ignorance.
The old pyramids often remain, useful in their own limited ways. And when confronting a complex problem, such as climate change, we see a small army of pyramids working together to make sense of the world.
As one such ‘pyramid’, we have the long and tangled story of the ‘atom’ concept, a story that began with the ancient greeks, and has taken centuries to untangle. Building this pyramid – the one that represents our understanding of the atom – we follow many false trails as well as brilliant revelations. Dalton’s understanding of the uniqueness and differentiation of atoms was one such hard fought revelation. There was the kinetic theory of gases that cemented the atomic/ molecular role in the physical properties of matter: the microscopic behaviour giving rise to the macroscopic properties such as temperature and pressure. Then there was the appreciation of the nuclear character and the electronic properties of atoms, leading ultimately to an appreciation of the fundamental reason for the structure of the periodic table, with a large dose of quantum theory thrown in. And then, with Chadwick’s discovery of the neutron, a resolution of the reason for isotopes very existence. Isotopes that, with the help of Urey’s brilliant insight, enabled their use in diverse paleoclimatogical applications that have brought glaciologists, chemists and atmospheric physicists together to track the progress of our climate and its forcing agents.
We can trace a similar story of how we came to be able to model the dynamical nature of our weather and climate. The bringing together of the dynamics of fluids, their thermodynamics, and much more.
Each brick in these pyramids starting as a question or conundrum and then leading to decades of research, publications, debate and resolutions, and yes, often many new questions.
Science never was and never will be the narrative of ignorance overcome by heroic brilliance overnight by some hard pressed crank cum genius. Galilieo was no crank, neither was Newton, nor was Einstein.
Even if our televisual thirst for instant gratification demands a science with instant answers, the reality is that the great majority of science is a long process of unfolding and developing the consequences of the fundamental principles, to see how these play out. Now, with the help of the computational facilities that are part of an extended laboratory (to add to the test tube, the spectometer, x-ray diffration, and so much more) we can see further and test ideas that were previously inaccessible to experimentation alone (this is true in all fields). Computers are the microscope of the 21st Century, as one molecular biologist has observed.
When we look at climate change we have a subject of undoubted complexity, that is a combination of many disciplines. Maybe for this reason, it was only in the late 1950s that these disparate disciplines recognised the need to come together: meteorology, glaciology, atmospheric chemistry, paleoclimatology, and much more. This convergence of disciplines ultimately led to the formation 30 years later to the IPCC in 1988.
At its most basic, global warming is trivial, and beyond any doubt: add more energy to a system (by adding more infra-red absorbing carbon dioxide to the atmosphere), and the system gets hotter (because, being knocked out of equilibrium, it will heat up faster than it loses heat to space, up and until it reaches a new equilibrium). Anyone who has spent an evening getting a frying pan to the point where it is hot enough to fry a pancake (and many to follow), will appreciate the principle.
Today, we have moved out of a pre-existing equilibrium and are warming fast, and have not yet reached a new equilibrium. That new equilibrium depends on how much more fossil fuels we burn. The choice now is between very serious and catastrophic.
The different threads of science that come together to create the ‘climate of consilience’ are diverse. They involve everything from the theory of isotopes; the understanding of Earth’s meteorological system; the nature of radiation and how different gases react with different types of radiation; the carbonate chemistry of the oceans; the dynamics of heat and moisture in the atmosphere based on Newtonian mechanics applied to fluids; and so much more.
Each of these threads has a well established body of knowledge in its own right, confirmed through published evidence and through their multiple successful applications.
In climate science these threads converge, and hence the term consilience.
So when did we know ‘for certain’ that global warming was real and is now happening?
Was it when Tyndall discovered in 1859 that carbon dioxide strongly absorbed infra-red radiation, whereas oxygen and nitrogen molecules did not? Did that prove that the world would warm dangerously in the future? No, but it did provide a key building block in our knowledge.
As did the findings of those that followed.
At each turn, there was always some doubt – something that suggested a ‘get out clause’, and scientists are by nature sceptical …
Surely the extra carbon dioxide added to the atmosphere by human activities would be absorbed by the vast oceans?
No, this was shown from the chemistry of the oceans to be wrong by the late 1950s, and thoroughly put to bed when sufficient time passed after 1958, when Charles Keeling started to accurately measure the concentration of carbon dioxide in the atmosphere. The ‘Keeling Curve’ rises inexorably.
Surely the carbon dioxide absorption of heat would become ‘saturated’ (unable to absorb any more heat) above a certain concentration.
No, this was raised in the early 20th Century but thoroughly refuted in the 1960s. Manabe & Wetherald’s paper in 1967 was the final nail in the coffin of denial for those that pushed against the ‘carbon dioxide’ theory. To anyone literate in science, that argument was over in 1967.
But will the Earth system not respond in the way feared … won’t the extra heat be absorbed by the oceans?
Good news, bad news. Yes, 93% of the extra heat is indeed being absorbed by the oceans, but the remainder is more than enough to ensure that the glaciers are melting; the great ice sheets are losing ice mass (the loses winning out over any gains of ice); seasons are being affected; sea levels are rising inexorably; and overall the surface temperature is rising. No need for computer models to tell us what is happening, it is there in front of us, for anyone who cares to look.
Many pour scorn on consensus in science.
They say that one right genius is better than 100 fools, which is a fine argument, except when uttered by a fool.
Even the genius has to publish, and fools never will or can, but shout from the sidelines and claim genius. All cranks think they are geniuses, whereas the converse is not true.
Einstein published, and had to undergo scrutiny. When the science community finally decided that Einstein was right, they did so because of the integrity of the theory and weight of evidence were sufficient. It was not a show of hands immdiately after he published, but in a sense, it was a show of hands after years of work to interrogate and test his assertions.
It was consilience followed by consensus (that’s science), not consensus followed by consilience (that’s political dogms).
We are as certain that the Earth has warmed due to increases in greenhouse gases – principally carbon dioxide, arising from human activities – as we are of the effects of smoking on human health, or the benefits of vaccination, and much more. And we are in part reinforced in this view because of the impact that is already occuring (observations not only theory).
The areas of doubt are there – how fast will the West Antarctica Ice Sheet melt – but these are doubts in the particulars not in the general proposition. Over 150 years of accumulated knowledge have led to this consilience, and was until recently, received wisdom amongst leaders of all political persuasions, as important and actionable knowledge.
The same is true of the multiple lines of enquiry that constitute the umbrella of disciplines we call ‘climate science’. Not a showing of hands, but a showing of published papers that have helped create this consilience of knowledge, and yes, a consensus of those skilled in their various arts.
It would be quicker to list the various areas of science that have not impacted on climate science than those that have.
In the two tables appended to the end of this essay, I have included:
Firstly, a timeline of selected discoveries and events over a long period – from 1600 to nearly the present – over which time either climate has been the topic or the underlying threads of science have been the topic. I have also included parallel events related to institutions such as the formation of meteorological organisations, to show both scientific and social developments on the same timeline.
Secondly, I have listed seminal papers in the recent history of the science (from 1800 onwards), with no doubt omissions that I apologise for in advance (comments welcome).
When running workshops on climate fluency I used a 5 metre long roll – a handwritten version of the timeline – and use it to walk along and refer to dates, personalities, stories and of course, key publications. It seems to go down very well (beats Powerpoint, for sure) …
All this has led to our current, robust, climate of consilience.
There was no rush to judgment, and no ideological bias.
It is time for the commentariat – those who are paid well to exercise their free speech in the comment sections of the media, at the New York Times, BBC, Daily Mail, or wherever – to study this history of the science, and basically, to understand why scientists are now as sure as they can be. And why they get frustrated with the spurious narrative of ‘the science is not yet in’.
If they attempted such arguments in relation to smoking, vaccination, germ theory or Newtonian mechanics, they would be laughed out of court.
The science of global warming is at least as robust as any of these, but the science community is not laughing … it’s deeply concerned at the woeful blindness of much of the media.
The science is well beyond being ‘in’; it is now part of a textbook body of knowledge. The consilience is robust and hence the consequent 97% consensus.
It’s time to act.
And if you, dear commentator, feel unable to act, at least write what is accurate, and avoid high school logical fallacies, or bullshit arguments about the nature of science.
Richard Erskine, 2nd May 2017
Amended on 17th July 2017 to include Tables as streamed Cloudup content (PDFs), due to inability of some readers to view the tables. Click on the arrow on bottom right of ‘frame’ to stream each document in turn, and there will then be an option to download the PDF file itself.
Amended 31st October 2017 to include a Figure I came across from Helen Czerski TED Talk, which helps illustrate a key point of the essay.
TABLE 1 – Timeline of Selected Discoveries and Events (since 1600)
TABLE 2 – Key Papers Related to Climate Science (since 1800)
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