Is the phrase, “we didn’t start the fire”, the title of a Billy Joel song from 1989, or a lesson in global climate change?

Since this is not a rock-and-roll blog, we’ll assume the later, for now.

Global Climate Change

In fact, scientific data suggest that humans may have started to modify global climate as early as 2,500 BC, or 4,500 years ago.

Maybe we didn’t start the fire – our ancestors did.

Data show that the human population was stable at about 3 million people until 6,500 years ago.

The change from hunter-gatherer to a farming lifestyle led to large-scale deforestation and animal domestication.

The agrarian lifestyle was extremely successful for humans, and by the time of the Roman Empire, there were 200 million people living on Earth (see Figure below).

The anthropological record shows that ancient people lived a lot like us (except for the internal combustion engine) and they ate a diet similar to ours.

Feeding the Masses & Methane Increase

In order to feed the additional 197 million people, vast fields were cultivated with grains, such as wheat, corn, and rice.

Paleoclimatologist, William Ruddiman, Ph.D. of the University of Virginia, and Jed Kaplan, Ph.D. of the University of Laussane in Switzerland cite the increase in atmospheric methane concentration about 5,000 years ago as evidence of how early humans not only modified the landscape but may have modified the atmosphere as well.