In the 1970s a rising world population and the finite resources available to support it were hot topics. Interest faded—but it’s time to take another look

In recent decades there has been considerable discussion in academia and the media about the environmental impacts of human activity, especially those related to climate change and biodiversity, but far less attention has been paid to the diminishing resource base for humans. Despite our inattention, resource depletion and population growth have been continuing relentlessly.

The most immediate of these issues appears to be a decline in oil reservoirs, a phenomenon commonly referred to as “peak oil” because global production appears to have reached a maximum and is now declining. However, a set of related resource and economic issues are continuing to come home to roost in ever greater numbers and impacts—so much so that author Richard Heinberg speaks of “peak everything.” We believe that these issues were set out well and basically accurately by a series of scientists in the middle of the last century and that events are demonstrating that their original ideas were mostly sound Many of these ideas were spelled out explictly in a landmark book called The Limits to Growth, published in 1972.

… For those few scientists who still cared about resource-scarcity issues, there was not any specific place to apply for grants at the National Science Foundation or even the Department of Energy (except for studies to improve energy efficiency), so most of our best energy analysts worked on these issues on the weekend, after retirement or pro bono. With very few exceptions graduate training in energy analysis or limits to growth withered. The concept of limits did live on in various environmental issues such as disappearing rain forests and coral reefs, and global climate change. But these were normally treated as their own specific problems, rather than as a more general issue about the relationship between population and resources.

… There is a common perception, even among knowledgeable environmental scientists, that the limits-to-growth model was a colossal failure, since obviously its predictions of extreme pollution and population decline have not come true.But what is not well known is that the original output, based on the computer technology of the time, had a very misleading feature: There were no dates on the graph between the years 1900 and 2100. If one draws a timeline along the bottom of the graph for the halfway point of 2000, then the model results are almost exactly on course some 35 years later in 2008 (with a few appropriate assumptions).

… Thus a key issue for the future is the degree to which fossil and other fuels will continue to be abundant and cheap. Together oil and natural gas supply nearly two-thirds of the energy used in the world, and coal another 20 percent.

… The important remaining questions about peak oil are not about its existence, but rather, when it occurred for the world as a whole, what the shape of the peak will be and how steep the slope of the curve will be as we go down the other side. The other big question about oil is not how much is left in the ground (the answer is a lot) but how much can be extracted at a significant energy profit.

Charles A. S. Hall is a professor at the College of Environmental Science and Forestry of the State University of New York at Syracuse. John W. Day is a professor emeritus in the Department of Oceanography and Coastal Sciences of Louisiana State University. Both are systems ecologists with wide-ranging interests and experience in energy and resource management.