Self-educated ice sage James Croll cracked the conundrum of why Earth periodically freezes over. He was feted in his time, so why did the world forget him?

A genius who worked out the choreography of glaciers, James Croll was not a people person J. Campbell Irons

HE WAS the janitor who unlocked the secret of how ice ages happen. The sickly son of a poor Scottish farmer, James Croll left school at 13 and became an itinerant labourer and failed salesman. But decades of private reading and an astonishing capacity for original thought saw him soar to scientific stardom. Croll became the father of climate-change research, and corresponded as an equal with the science heavyweights of the day, including Charles Darwin, Lord Kelvin, Arctic explorer Fridtjof Nansen and geologist Charles Lyell. Yet you have probably never heard of him.

His star waned, and his insights about the cosmological causes of the great glaciations sank from view, until revived half a century later by Serbian mathematician Milutin Milankovitch, who took the plaudits. Croll died in penury, a footnote even on his own gravestone. Was he a victim of Victorian snobbishness? Or might he have fared even worse had he lived in the modern age?

Croll was born in 1821 and raised on a smallholding on moorland in rural east Scotland, land he worked from a young age. His sporadic schooling ended at 13, but by then he had stumbled across a copy of The Penny Magazine, the New Scientist of its day. He became hooked on science. By 14, he was reading the great science texts of the time. “At first I became bewildered, but soon the beauty and simplicity of the conceptions filled me with delight and astonishment,” he later wrote in an autobiographical sketch. “I …