Alfred Wegener and continental drift: Crackpot or heretic?

It is not uncommon for writers who wish to disparage science to refer to Alfred Wegener and his theory of ‘continental drift’. People laughed at him, they say, and ridiculed his ideas, and they are not laughing now. The establishment saw continental drift as a crackpot theory, or a threat to some existing theory. He was a heretic against the scientific establishment, and did not live to see his ideas triumph. Here is another example of how science is only, or only a little better than, a set of opinions of scientists that can be overthrown at any time. What is called ‘science’ is just the opinion of the majority of scientists in a field, and a plucky loner (Wegener was not a geologist) may eventually overthrow the established opinion and receive the credit he deserves.

This view of science is particularly comforting to religious extremists, postmodernist philosophers and science-deniers of all stripes (climate change, AIDS, vaccines, and so on).

But it’s false (and could not be true in its full-blown postmodernist form in any case, because if it was true, why should the heretic be any more right than the established views?)

Quite recently, Matt Ridley, who used  to be an admired science writer in his own field of biology, invoked Wegener (amongst others) as an example of a heretic who was persecuted by scientists but eventually  triumphed. This is by way of lauding a ‘sceptic’ who Ridley thinks (without presenting any evidence) will one day show that humans are not causing  global warming.

Perhaps I’ll come back to Ridley later. For this occasion I want to comment on Wegener, and I’ll start by stating some facts.

  • Wegener’s theory was taken seriously by geologists, even though they were rightly sceptical.
  • Wegener was not a heretic, because he had nothing to be heretical against.
  • Wegener was not the father of plate tectonics, which is not the same thing as ‘continental drift’.
  • Science was working pretty much as it should in his case. (And I dare say this was probably the case for most of the ‘heretics’ Ridley mentions.)

Let’s consider the state of geology in Wegener’s day, around 1915-30. The world had been mostly mapped, and many geological structures around the world, particularly those of potential economic value, had been mapped too. The main geological periods had been identified, many rock strata had been placed in their correct order and some absolute dates had been obtained using radioisotopes, showing that the world was much older than previously thought, even though the dates were not as accurate as those we have now. The geological discoveries tied in with the paleontological (fossil) discoveries, which were explained by evolutionary theory.

But there were lots of puzzling observations of the earth that could not easily be explained. The apparent ‘fit’ of the outlines of some continents – and, particularly, the rock formations on each side – was just one of them, the one that engaged Wegener.  But there was much more.

  • Why were there mountains, if the earth is as old as was now known? It was known that the processes of erosion of rocks would remove mountain ranges in tens or hundreds of million years.
  • Why are the largest mountains in the huge Alpine-Himalayan and Andes-Rockies ranges?  Why are these ranges made up of sediments – as identified by the fossils in them – that had apparently been deposited in submarine trenches called ‘geocynclines’ tens of kilometres deep? And where are the geosynclines of the present day, and if there are none, why not?
  • Why are there volcanoes and earthquakes, and why are they located where they are?
  • Why do some rocks show glaciation in the tropics and others show tropical life in the polar regions? Did the rocks move, or did the climatic zones?

And so on and on. It’s important to remember that a lot of details we now know were not available then and did not become available till the 1950s and 1960s. One particularly important clue that was missing was that the ocean floors are very much younger than most of the continental rocks, less than about 200 million years old, and were formed by spreading from ridges of volcanic activity, such as the Atlantic mid-ocean ridge. Another important detail that needed to be understood is the structural relationship between the continental shields, the oceans and the mantle beneath  them.

There were actually many theories for some of the phenomena, but nothing that explained it all. In such a case, scientists are right to be sceptical. We tend to consider theories better if they bring together lots of isolated observations into one consistent body of explanation, as evolution does in biology and quantum theory does in physics and chemistry. There was no such thing proposed at that time for geology (evolution dates of course from Darwin’s time and the foundations of quantum mechanics were mostly laid in the 1910s/20s).

Some years ago I was on one of many field trips in the mountains of northern Oman. These offer some of the most spectacular (and visible, given the desert climate) geological displays in the world. Vast sheets of rocks, many of them from the bed of a long-gone ocean, and some of them from deep in the volcanic ocean crust, have been thrust far inland over an older land surface, in some places rucking up  the older rock into mountains thousands of metres high, like a vast carpet on a slippery floor. One of the other participants, an FRS in geology, commented that until the coming of plate tectonic theory the only available explanation for this, and all the rest of geology, was magic.

One thing to remember is that a theory must explain those observations that are, on the face of it, inconsistent with the theory. For example, ‘continental drift’ explains why some facing shorelines approximately fit (for example, eastern South America and south-western Africa) but what about those many shorelines that don’t fit?

Another thing that was missing was a mechanism for continental drift. To accept causal relationships, scientists want to know the exact mechanisms by which one thing causes or relates to another. In Wegener’s own field of meterorology, the underlying physical mechanisms of the weather were already known.  In the early 20th century, lots of fundamental work was going on into how chemical reactions occur (their mechanisms). Nowadays, there are scientists studying the mechanisms of genetics and how organisms develop. Wegener had nothing to offer on these lines regarding how continental drift occurred.

Crucially, there was at least one other theory that seemed to explain the observations and it was probably more acceptable at first than continental drift, although it faded as more evidence came in. That is, that the continents were originally connected, but that the land between them had foundered beneath the sea – perhaps more plausible, in the absence of relevant evidence, than moving continents!  This other theory eventually was disproved by the finding that the ocean floors are of very different material from the continental shelves.

There is a book reviewing the state of earth science around the time of Wegener’s death (J A Steers, The Unstable Earth, 3rd ed 1942, originally published 1932) which devotes many pages to discussing continental drift and the evidence relating to it. Clearly the theory had been taken very seriously but as it was incomplete and had at least one rival theory, geologists were right to be sceptical. In fact (as Karl Popper explained) it is right and proper to be as critical as possible of any theory, as it is the one that survives criticism the best that eventually prevails. No doubt Wegener experienced personal remarks and academic bitchiness, but he probably didn’t receive much worse than other proponents of conjectural theories receive. (Incidentally, the objections to Semmelweiss – another of Ridley’s ‘heretics’ – were probably much to do with his attitude and behaviour towards other physicans).

And what theories the Steers book contains! There are many, covering different aspects of geology, and some of them seem pretty strange to us now. For example, there was a theory that the earth had a tendency to collapse into a tetrahedral form, at the same time creating the force that pushed up mountains. This was based on the observation that the main continental shields of the earth form approximately the corners of a tetrahedron, which we now know (whether it is true or not) is no more than a coincidence and a red herring. Much of the theorising in the book  is based on the suggestion that the earth is contracting through cooling.

The book makes it clear that at that time the evidence was stacking up in favour of continental drift and the theory of land bridges was losing favour. Wegener’s theory is given at least the same prominence of that of a prominent expert on earthquakes, Harold Jeffreys, who proposed that the earth was undergoing thermal contraction.

The mechanism of what would later be called plate tectonics (attributed to Arthur Holmes) is also discussed in the book in rudimentary form – the idea that continental plates are mobile on the mantle beneath them.

Before plate tectonics, geology was a mass of unexplained and puzzling phenomena and various theories were widely debated. It was plate tectonics that brought them all together in one wide-ranging and unifying and satisfactory explanation. This happened in the 1950s and 1960s. I won’t go into it here as there are plenty of places where you can read about it. But plate tectonics is much, much more than just ‘continental drift’. Wegener made a contribution to our later understanding – which he did not live to see as he died on an expedition to Greenland studying Arctic weather (his own research field). But there is no reason to regard him either as a heretic or a victim of unreasonable doubt.

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Drama in the Karakoram

[BPSDB] A drama, largely unnoticed in the rest of the world, has been going on in the Hunza valley, in the beautiful and terrible mountains of northern Pakistan. In January, a large landslide in January killed about 20 people, cut off the Karakoram Highway between Pakistan and China, and blocked the Hunza river, creating a large lake which has been steadily growing in size.

Pakistan Army engineers have been trying to create a spillway to drain the lake, but overtopping of the natural dam seems imminent. There is a danger that the dam may give way, creating a flood that will threaten tens of thousands of people living downstream. The situation is made more dangerous by further rock falls and the summer melting of the snow on the mountains.

A number of bloggers have been covering events, including Dave Petley of Durham University: here and here.

The biggest control knob: Carbon dioxide in earth’s climate history

[BPSDB] By Richard B Alley of Penn State University.

This was the keynote lecture at the American Geophysical Union meeting (a vast conspiracy of scientists to find out all they can about how the Earth works) last year.

It’s a good summary of what we know about the role of CO2 in the Earth’s climate, a proof that climate scientists really do take into account all the climate changes that have happened over the Earth’s history, and why that knowledge is still bad news for us as we belch huge amounts of buried carbon into the atmosphere.

Vodpod videos no longer available.

more about “A23A“, posted with vodpod

Countering disinformation on climate

[BPSDB] In the wake of the latest outrageously dishonest headlines misquoting Phil Jones, the excellent  Open Mind blog presented a good account of the error, and also initiated a civilised and productive discussion on how to present the facts to the general public. I urge you to read it. I hope to post some thoughts of my own on this in the near future.

Why should I make the data available to you

[BPSDB] In many comments on the CRU hack I’ve seen it alleged that Professor Phil Jones of the University of East Anglia Climate Research Unit denied his data to another researcher with the words, “Why should I make the data available to you, when your aim is to try and find something wrong with it?”

Whenever I’ve seen it quoted, it’s implied that  Jones made the comment in one of the emails. I finally got around to looking for it, in the file FOIA.zip I downloaded soon after the hack was made public – and it ain’t there. Not perhaps surprising, as it really doesn’t sound like the sort of thing an academic would say, except jokingly or sarcastically.

Indeed, the words are there. In August 2007, a fellow researcher warns Jones that the words are being attributed to him by someone else. In October 2009, another colleague sends Jones a copy of the text of an article in the National Review of 23 September 2009. In this Patrick Michaels quotes Warwick Hughes as alleging that Phil Jones said, “We have 25 years or so invested in the work. Why should I make the data available to you, when your aim is to try and find something wrong with it?”.

So it doesn’t appear to be evidence that Jones actually wrote it.  Given the unreliability and political commitment of all the links in this chain, and that this was one of the main pieces of evidence for the supposed ‘conspiracy’, I think there is even less evidence of wrong-doing.

Conspiracy theories have a tendency to spawn new conspiracies: here’s a climate ‘sceptic’ who thinks the CRU staff may have leaked the emails themselves to make ‘sceptics’ look stupid. If so, they’ve succeeded.

Words: Correction, Compensation, Adjustment, Proxy, Trick

[BPSDB] Years ago, when I was a researcher, I used a technique called ‘infrared spectroscopy’ a lot.  It involves passing infrared radiation through a sample of a substance, then splitting the infrared radiation up into its various frequencies (a spectrum) and measuring which frequencies are absorbed by the substance. Most substances (though not all) absorb IR radiation.

The resulting pattern of peaks, called bands, can be used in analytical chemistry to identify compounds, if their IR spectra are known. Under favourable conditions, such as the vapours at low pressure I often worked with, you can get information that will help (along with other techniques) to discover the actual shapes of the molecules, and even to discover facts about the internal electronic structure.

So, in theory, all you do is pass the IR through the sample and record the spectrum, right? No. Between the lamp and the sample are other things that absorb IR. These could include the solvent (if you’ve had to dissolve the sample), but, in particular, there is carbon dioxide, which is a component of air that strongly absorbs IR. So your spectrum includes bands from the interfering substances, which will complicate matters and likely obscure details of the spectrum you want to see.

But there is a clever trick (that word came immediately to my mind writing this, in the sense of a clever thing to do). That is, you split the IR beam into two, and pass one half through the sample and the other through a path of the same length containing all the things (air, solvent, etc.) except the sample itself. Then you can electronically subtract the signal from the reference beam (the one without sample) from the signal from the sample beam. And you are left with the signal that comes from the sample alone. Clever, eh?

This is called correction or compensation. There is nothing dishonest about it. The result is a genuine spectrum. If anyone is being cheated, it is nature being tricked into giving up her secrets, as without the compensation or correction you would have much less, if any, information about the sample spectrum.

I mention this, as hordes of global warming ‘sceptics’ have been crying ‘fraud’ simply through seeing words like ‘correction’, ‘adjustment’ and even ‘trick’ in some otherwise unremarkable stolen emails containing informal correspondence between climate scientists. These words do not in themselves imply anything nefarious. Now there may have been improper behaviour on the part of the scientists, but that would require some contexts for these words, providing some actual evidence. But no evidence for serious wrong-doing (apart, apparently, from getting irritated with ignorant harassment) has been presented.

Corrections are not limited to the lab. Whenever you press the ‘tare’ button on a set of kitchen scales, you are making a correction, by subtracting the weight of the bowl from the flour you are weighing out. Without that correction you will have a less satisfactory cake. Corrections, or compensations, or adjustments, are an essential part of the tricks needed to extract real data from the raw data of the real world.

In science, most things are not measurable directly. Temperature is one of them. When you measure a temperature, you are actually measuring an electric current that changes numbers on a display or moves a needle on a dial. Or you are measuring the expansion of a liquid (alcohol or mercury) along a tube. Neither method measures temperature directly, which is, in fact, impossible. What you are measuring is a proxy for temperature: another measurable quantity that is related to temperature in a way that is known from theory and tested by practice. But the manufacturer still has to make corrections to ensure that the fixed points of the measuring device correspond to the fixed points of the standard temperature scale. Building these corrections in is called calibration.

Actual measurements of temperature, using thermometers, go back only a short time, at most a couple of centuries in relatively few places. That means that scientists trying to study temperature way back in history or beyond have to use proxies – whatever they can find, wherever they can find them. The proxies include annual tree-ring growth, ratios of isotopes of oxygen in ancient snow, and the patterns of annual deposition in lakes (varves). These may not vary in a straight line relationship with temperature. Also, nature may inconsiderately have placed the proxies in different places at different times, such as trees growing at different heights.

To try to make these separate items match up, you need to calibrate, or adjust, the data, so they represent the temperatures correctly. For example, you may need to allow for trees growing at different rates at different heights. You can imagine that a great part of research is given over to debate about these corrections. But there is nothing essentially dishonest about doing this. If you find that numerous different proxies, when compared over the same period of time, agree pretty well, then you can have reasonable confidence that the proxies are measuring the same thing. So it is with the so-called ‘hockey-stick’ graphs.