The Janitor Who Cleaned Up an Ice Age Mess

Paterze glacier. The longest glacier in Austria.

There are times when ennui leads one to do something out-of-the-blue. For example, a bored cat may decide that you need a weekly offering of half-dead prey into your life for the simple reason that it has no other cat things to do. Back in Roman times, Caligula may have been bored by the irksome rabble of the senate which led him to elect Incitatus, his darling steed, as consul. A spur of the moment decision which bothered the neighbourhood, and a truly effective effort to push the senators off their high horses.

Sometimes, habitual and listless repetition of work inspire these instantaneous and spontaneous acts of abandon. In most cases, to an extent that some do things that are completely alien from their assigned tasks. That’s what the janitor of the University of Strathclyde did. The menial tasks of cleaning corridors and classrooms were just too boring. There were other areas that needed immediate remedy. Especially the ice age theory of climate change. And so this janitor cleaned up the mess by adding strength to the theory using astronomy and mathematics that he had just picked up by himself. His name was James Croll (1821-1890).

443px-James_Croll.jpgJanet Ellis, the wife of stonemason David Croil, just gave birth to a baby boy. It was just a day after the small Scottish hamlet of Little Whitefield celebrated new year. Perhaps the sound of celebration and merriment urged the curious foetus to peek out of the womb but then inevitably triggered a series of labour pangs that became uncontrollable. In any case, James Croll was born in 1821 January 2.

Life was hard for the family. So were the rocks that David struck, which yielded little profits despite the heavy hits. As a result, they chiefly relied on whatever bounty their small homestead blessed them with. Which was not much. Meager, but not to the point of destitution. Thus, Croll and his other siblings couldn’t enjoy full formal education. Time spent inside the classroom was better spent tending the crops and running errands. Money spent for their education was better spent on food and shelter. But in 1932, Croll’s days of lethargic labour came to a brief interregnum when, by chance, he stumbled upon an issue of Penny Magazine – the journal of The Society for the Diffusion of Useful Knowledge.  The society successfully lived up to its name.

The magazine welcomed the young Croll into the world of philosophy, science, and scholarship – he has never looked back since. A lifelong interest in philosophy and science ensued, and he was adamant to follow its course. The obvious handicap of having little to no formal education was not to stop him from pursuing academics.

Only the harsh circumstances of life did.

Croll had to find other ways to help the family, since their small croft didn’t turn up much. A saga of tiresome but unrewarding events commenced: he first worked as a millwright at the age of 16; then moved on to the peculiar Victorian profession of being a house joiner; after an accident ended further activities, he tested the waters of commerce as a tea trader; when that became financially futile, he decided to open up a temperance inn; that also didn’t work out well, so he tried his luck as an insurance salesman; which ironically failed to ensure a better future for him, leading him to his next and final stop in this series of hapless happenings, the doors of Strathclyde University.

At the age of 38, Croll was hired as a university janitor. A wonderful opportunity for sanitation and self-education. Under the pretence of cleaning, he would spend hours and hours of study inside the library after all the students and personnel had gone home. He would copy data, equations, notes, and other things scribbled on classroom blackboards before he swiped them clean. Croll also acquainted himself with the intellectual giants of his time and sent them inquiries for data, correction, and critique, as well as informing them of his own thoughts. He was very well positioned in the academe, though his job wasn’t entirely complimentary.

Croll’s main scientific area of interest was in the patterns of glaciation across the earth’s history. The Swiss science superiore Jean Louis Rodolphe Agassiz, or more popularly known as Harvard’s Louis Agassiz, proposed in 1840 that a period of global glaciation happened in the earth’s past in a paper titled Études sur les glaciers (Studies on Glaciers). According to Agassiz, this ice age was so widespread and massive that it stretched from the north pole down to the Mediterranean, with large swathes of land and life (some leading to extinctions) being buried under ice in the process.  Agassiz’s radical proposal explained two phenomena that geologists at that time failed to explain: 1.) the presence of large rocks, called erratic blocks, in surprising places – large drifting glaciers carried these rocks and laid them in their current positions as the ice melted; and 2.) glacial marks, or etchings left on rocks as moving glacier rubbed against it – sure, a fire can burn and leave marks, but passing blocks of large cooled objects also left distinctive scars.

Agassiz’s ideas were largely borrowed from other sources. It wasn’t originality that brought him to the forefront of this cool new idea, but it was his persuasiveness and zeal in bringing this idea to the spotlight of science. But despite his unrelenting energy, the theory of ice ages was thawing. No one could give a precise explanation of how and why it happened. “This frozen earth theory,” the scientists said, “we should let it go.” It was only in 1864, when the Philosophical Society published an article titled On the Physical Cause of the Change of Climate During Geological Epochs that the theory stood on solid frozen foundation.

The author of that paper was James Croll.

“No fact in geological science is better established than that in former periods of our earth’s history great changes of climate, in so far at least as the northern portions are concerned, must have taken place,” starts Croll. He then outlines his addenda to the theory, making two linear points that posited a possible explanation for global glaciation. First, he forwarded the idea that little perturbations in the earth’s astronomical cycle around the sun can cause temperatures to change drastically, as well as decrease the amount of sunlight reaching earth to melt ice. When the earth’s orbital cycle is stretched by the gravitational pull of other planets, its elliptical trajectory is elongated in a way that its time away from the sun is lengthened. Leading to Croll’s second important point in the paper and developed further in his later publications, that of “positive feedback”. As the earth moves further and further from the sun, it starts to get cooler. Since it also spends more time away from the sun than near it, it will then maintain a longer period of cold in its orbit, thus adding to the cooling effect brought by its distance away from the sun. This leads to the formation of ice and more ice. As ice sheets spread across the earth, this creates a wider reflective surface that blocks much of the sun’s incoming rays, ricocheting them back to space (owing to the high albedo of white objects, or simply their high reflectivity). Which ultimately means that the amount of energy from the sun bombarding the earth, already decreased by the earth’s distance away from the sun, is further reduced by the ice’s reflective properties – thus, little ice is melted, and more ice is made.

Of course, Croll’s theory was incomplete, and some of his conclusions were wrong (like his insistence that the last global glacial event was more than 100,000 years ago) – we now know better. He had to make do with the resources and materials at his disposal, which weren’t much compared to sophisticated equipment and techniques employed by today’s climate scientists. But Croll was in the right ball park, and his snowballs hit the target. His astronomical theory of climate change was later found to be correct and improved by the Serbian climatologist Milutin Milanković. The importance of positive feedback was in-itself revolutionary – way ahead of its time. Both ideas are now fundamental in climate science.

Surprisingly, posterity seems reluctant to afford Croll a positive feedback.

The astronomical events and factors that lead to drastic climatic changes were not named after him, even if he was the one who pioneered that view. The modern form of Croll’s ideas are named Milanković cycles, after the Serb who worked on and made them more cohesive. His name is also almost always absent in discussions about great pioneering scientists. Even if the world’s most immediate scientific concern at the moment – climate change – stands on the firmament of his work. No one knows exactly why he has faded from the popular and public sphere. Or perhaps not a lot can be bothered to know.

After all, students who enter clean classrooms don’t really appreciate the work of janitors the night before. They will, though, if they slipped on icy and wet surfaces that weren’t cleaned up.

Thinning polar ice caps due to global warming trying their best to reflect the sun’s rays.


Fleming, James Rodger. (2006). James Croll in context: the encounter between climate dynamics and geology in the second half of the nineteenth century. History of Meteorology. 6. 43-53

Sugden, David. (2014). James Croll (1821-1890): ice, ice ages and the Antarctic connection. Antarctic Science. 26(6). 604-613

4 thoughts on “The Janitor Who Cleaned Up an Ice Age Mess

  1. P.S. The Wikipedia article on Croll notes that he worked in the Edinburgh office of the Geological Survey of Scotland, was elected Fellow of the Royal Society, and awarded an honorary degree by the University of St Andrews — facts that you intentionally left out because they don’t fit your “lowly janitor cleaning up science” motif.

    Liked by 1 person

    1. Thank you for the comments! Mind pointing out where being “clever” got in the way of substance?

      Sure! They were intentionally left out because the point of the article is to highlight the event when he forwarded the radical astronomical cause of climate change. Him receiving those accolades comes only AFTER the fact.

      Also, him being awarded all that doesn’t automatically mean that he escaped his sorry lot. He failed in mathematics and English composition when he took the Civil Service exam, thus he couldn’t enter the Geological Survey of Scotland. It was only when Lord Kelvin and his other friends intervened that he got appointed as member. His election to the ranks of the Royal Society was largely thanks to his 1875 book Climate and Time in Their Geological Relations – a book written in ill health, thanks to the years of hardship that followed his childhood (he had developed a debilitating migraine as a young man and it worsened throughout the years, probably because of having failed to secure healthcare). He also turned down an invitation to do a lecture for the Royal Institution as he still saw himself as this “lowly janitor” who preferred doing science in the background. In his last years, he was suffering from a developing heart ailment and relative poverty, as he saw his pension from his survey work largely reduced. So If I mentioned these, it would just strengthen my initial point. And there’s no need for that.


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