James Croll: The Ice Age

In the mid-19th century James Cross, a Scottish scientist, suggested that variations in the earth’s direction near the sun was responsible for cooler time periods; however, this view wasn’t widely accepted.

In 1857, an independent scholar and self-taught astronomer, James Croll, argued that until we find the cause of the “Ice Age” we will not know the rest of the story. Making the assumption that the earth is warmed by the sun, Croll decided to calculate the variations of the earth’s orbit as well as its tilt. Due to the earth’s tilt the Northern and Southern Hemispheres receive varying amounts of direct sunlight and would contribute to hot-cold cycles. As part of his research, he plotted the data points of valleys and peaks over thousands of years. Without modern methods of dating Croll’s estimates could not be verified by the scientific community.

A few years later he developed a way to measure the earth’s temperature in any location and proposed that it was the tilt in the earth’s axis that was a contributing factor in the cause of the “Ice Age”. In addition, he learned that snow also plays a major role in reflecting solar energy from the earth’s surface; and concluded that changes in the earth’s orbit could cause climate changes. Upon further investigation he also discovered that climate changes amplified each other and this evidence led to what we now call the “Ice