James Croll facts for kids
Quick facts for kids
James Croll
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| Born | 2 January 1821 Little Whitefield, Perthshire, Scotland
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| Died | 15 December 1890 (aged 69) Perth, Scotland
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| Nationality | Scottish |
| Occupation | Scientist |
| Spouse(s) |
Isabella Macdonald
(m. 1848–1890) |
James Croll (born January 2, 1821 – died December 15, 1890) was a Scottish scientist from the 1800s. He was also a Fellow of the Royal Society, a special honor for top scientists. He came up with an important idea about how Earth's climate changes. His theory was based on how our planet moves around the Sun.
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James Croll's Early Life and Work
James Croll was born in 1821 on a farm called Little Whitefield in Scotland. His parents were David Croll and Janet Geddes. He mostly taught himself what he knew, which is pretty amazing!
At 16, he started learning to be a wheelwright, someone who builds and repairs wheels. Later, because he wasn't well, he worked as a tea merchant. In 1848, he married Isabella Macdonald.
In the 1850s, James managed a hotel that promoted healthy living. After that, he worked as an insurance agent in different cities.
Becoming a Scientist
In 1859, James Croll got a job as a janitor at the museum of the Andersonian University in Glasgow. This job changed his life! He could use the university library to read many books. He taught himself physics and astronomy to develop his scientific ideas.
From 1864, Croll started writing to Sir Charles Lyell, a famous geologist. They discussed how ice ages might be linked to changes in Earth's orbit.
Croll thought that changes in Earth's orbit could make the Gulf Stream (a warm ocean current) move differently. This would bring less heat to the Arctic region. More ice would then reflect more sunlight, making the Earth even colder. This is called a "feedback loop." His ideas were published in a science magazine in 1864.
This important work led him to a new job. He became a map and letter keeper at the Geological Survey of Scotland in Edinburgh. The director there, Sir Archibald Geikie, encouraged his research.
James Croll wrote many books and papers that were very important in science at the time. One of his most famous books was Climate and Time, in Their Geological Relations, published in 1875. He also wrote to Charles Darwin about how rivers cause erosion.
In 1876, he became a Fellow of the Royal Society. This is a very high honor for scientists. He also received an honorary degree from the University of St Andrews. He retired in 1880 because he was not well.
James Croll's Theory of Ice Ages
Croll was a leading scientist who believed that changes in Earth's orbit caused climate change. This idea is now known as the "Astronomical Theory of Climate Change."
He used math from another scientist, Urbain Le Verrier, to figure out how Earth's orbit changes. Croll thought that less sunlight in winter would help snow build up. He was the first to connect this to the idea that ice and snow reflect sunlight (called albedo). This reflection would make the Earth even colder, making the changes bigger.
Croll also suggested that lots of snow would change wind patterns. This could move warm ocean currents like the Gulf Stream. He believed this could lead to a long-lasting ice age. He thought that when Earth's orbit was more oval-shaped (high orbital eccentricity), winters would be colder when Earth was farthest from the sun. He predicted ice ages would happen every 22,000 years and switch between the northern and southern parts of the world.
Croll's theory predicted many ice ages. It also suggested that the last ice age ended about 80,000 years ago. At the time, scientists were just starting to find proof of multiple ice ages. They were very interested in a theory that could explain this.
However, scientists couldn't accurately date how old sediments were back then. Also, measurements of how fast Niagara Falls was moving suggested the last ice age ended much more recently. This made some scientists doubt Croll's theory.
Even though his theory was questioned, Croll's basic idea was very important. The idea that changes in Earth's orbit affect temperatures is now known as Milankovitch cycles. This idea was further developed by Milutin Milankovitch and was finally proven correct in 1976.
James Croll's Writings
- 1857: The Philosophy of Theism
- 1864: On the Physical Cause of the Change of Climate During Geological Epochs
- 1867: On the Excentricity of the Earth's Orbit and its Physical Relations to the Glacial Epoch
- 1875: Climate and Time, in Their Geological Relations, a Theory of Secular Changes of the Earth's Climate
- 1885: Climate and Cosmology
- 1889: Stellar Evolution and Its Relations to Geological Time
- 1896: Autobiographical Sketch of James Croll, With Memoir of His Life and Work (published after he died)
Images for kids
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The Museum at the Andersonian University in Glasgow, where James Croll worked.
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The inside of the Andersonian University Museum.
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James Croll's family headstone at Cargill cemetery.
