James Croll

James Croll (2 January 1821 – 15 December 1890) was a Scottish physical scientist who was the leading proponent of an astronomical theory of climate change in the 19th century. The son of a stonemason and crofter from Cargill in Scotland, he started work as a millwright, but became caretaker at Anderson's College, Glasgow, in 1859. He was later appointed resident geologist in the Edinburgh office of the Geological Survey, where he remained until his retirement in 1880.

His insights into the interplay between astronomical and geological factors – into cosmic physics and climate dynamics -- were extremely influential. In 1875 Croll published his major book, ‘’Climate and Time’’, which came to have a profound influence on geologists around the world. The leading geologist of his day, Charles Lyell, revised his ‘’Principles of Geology.. in response to Croll’s theory. His view was notably by [[James Geikie in his pioneering work The Great Ice Age (1874–84),

In 1864, Croll published an article entitled “On the Physical Cause of the Change of Climate During Geological Epochs.” In it, he proposed that periodic variations in the earth’s orbit around the sun accounted for the periodic variations in climate evidenced by geological evidence of ice ages , and alternating cold and warm periods in each hemisphere (i.e. that ice ages in the Northern Hemisphere coincided with interglacials in the Southern Hemisphere. He proposed that feedback mechanisms, including the radiative effects of the ice fields, enhanced formation of cloud and fog, changes in sea level, and the mixing and redirection of warm and cold ocean currents enhanced the climatic changes initiated by the orbital changes. Because of uncertainties in the timing of ice ages, and because Croll’s theory predicted glaciation in only one hemisphere at, the theory was disregarded at first.

In 1876, Croll was elected as a Fellow of the Royal Society and was awarded an honorary doctorate from the University of St Andrews.