“You cannot sustain population growth. It’s not debatable,” says University of Colorado Boulder Professor Emeritus Al Bartlett. “It’s based on arithmetic. It’s not debatable unless you want to debate arithmetic.”

In an educational video entitled “Population, Consumption, and Climate: A Conversation with Al Bartlett,” the professor reprises themes from his notorious talk on population. Bartlett came to CU-Boulder in 1950 to join the Department of Physics. In the 1950s and today, he notes society and governments view steady growth as the centerpiece of the global economy.

“I got to thinking about the fact that people didn’t really understand the arithmetic of steady growth,” he said. “So I put together a talk. I first gave it in September of 1969 on the arithmetic of growth.”

Bartlett has since delivered that well-known lecture more than 1,700 times to audiences worldwide. He often cites an analogy of human population growth and multiplying bacteria. Using an animation that shows bacteria doubling over a fixed period of time, the video illustrates the arithmetic of steady growth and how quickly resources are depleted as growth continues.

“There will be limits,” cautions Bartlett.

The world population topped 7 billion in March 2012, according to the United States Census Bureau. Bartlett explains that despite the fact that population growth rates in developing countries may be 3-4 times higher than the U.S. rates, a significant problem with population resides in the United States because of high per capita demand for energy and resources.

“The average child born in the United States will have, over its lifetime, 10-20 times the impact on world resources as a child born in an underdeveloped nation,” he says.  “So we’ve got to address the problem at home.”

In addition to the strain on the earth’s natural resources, excessive consumption contributes to climate change because resource extraction, manufacturing, and transportation produce a great deal of carbon dioxide. And, according to Bartlett, “if any fraction of global warming can be attributed to the actions of humans, that’s all the proof you need to say the human population today is greater than the carrying capacity of the earth.”

Population, Consumption, and Climate: A Conversation with Al Bartlett is part of a video series viewable at  Learn More About Climate, produced by CU-Boulder’s Office for University Outreach and Landlocked Films.

The Learn More About Climate initiative brings climate change-related information to communities across the state.The website is an online outreach tool that localizes climate change through interviews with leading scientists and everyday Coloradans to explain how climate change is affecting our state. The site also offers resources for teachers, students, policy makers, and community members who want to learn more about this critical issue.