James Croll (1821-1890) was a Scottish scientist and one of the key figures in the study of climate change and its relation to Earth’s orbital variations. He was born on January 2, 1821, in Little Whitefield, near Perth, Scotland.

Croll received only a limited formal education but displayed a remarkable aptitude for self-learning and scientific inquiry. He had a particular interest in natural philosophy (what we now call physics) and mathematics, which he pursued on his own.

His most significant contributions came in the field of geology and climatology. He worked as an assistant at the Perth Observatory, where he gained expertise in meteorology and astronomical observations. Later, he became a janitor at Anderson’s University in Glasgow, which allowed him access to scientific literature and resources to continue his studies.

Croll’s most influential work, published in 1864, was the book titled “Climate and Time in Their Geological Relations.” In this book, he proposed a theory explaining how changes in Earth’s climate could be influenced by variations in the planet’s orbit and axial tilt. He suggested that cyclic changes in Earth’s orbit and axial tilt, known as Milankovitch cycles (later named after the Serbian mathematician Milutin Milanković, who expanded on Croll’s work), could be responsible for triggering ice ages and periods of global warming over long geological time scales.

Croll’s ideas were groundbreaking and laid the foundation for future research into the astronomical theory of climate change. However, during his time, his work was met with mixed reactions and did not receive widespread recognition.

It wasn’t until the early 20th century, when Milanković further developed and refined the astronomical theory of climate change, that Croll’s contributions were more fully appreciated. Today, the Milankovitch cycles are widely accepted as significant factors influencing Earth’s long-term climate variations.

James Croll passed away on December 15, 1890, in Perth, Scotland. Despite facing challenges during his lifetime, his work has had a lasting impact on the study of climate change and our understanding of the long-term climatic history of our planet.