Testifying at a meeting of the U. S. Senate Committee on the Environment and Public Works on March 21, 2007, Vice President Al Gore described global warming as “A true planetary emergency”. Neither I nor a majority of Americans agree with that, though I do not for a minute deny that Earth has been warming up.
I do agree, however, with Richard Heinberg, who wrote recently that “It’s not just climate change that threatens us, but depletion of resources including oil, natural gas, coal, fresh water, fish, topsoil, and minerals (ranging from antimony to zinc, and including, significantly, uranium; as well as destruction of habitat and accelerating biodiversity loss–which is exacerbated by climate change, but is also happening for other anthropogenic reasons. In essence, there are just too many of us using too much too fast.
“I would like to offer some perspective on how we have gotten to this point and what it might mean for our future, though I agree with Nassim Taleb that we are incapable of actually predicting the future. For the sake of argument, let’s assume that modern humans, Homo sapiens, can be traced back to an African origin around 160,000 years ago.
For most of those 160,000 years our ancestors lived in small groups as hunters and gatherers. Life expectancies were short and populations grew only very slowly. About 10,000 years ago humans started to practice rudimentary agriculture, mainly because global warming was already occurring as the most recent Ice Age was ending. As Jack Weatherford noted, “Around the world, humans seem to have switched from foraging to farming because of the whole set of changes produced by global warming.” Agriculture increased Earth’s carrying capacity for humans, and as crops and domesticated animals were improved and diffused around the world, population growth accelerated somewhat, but it was still, by modern standards, slow, and it was also sporadic. Populations grew when times were good, then declined when times were bad. Famines, diseases, and wars would take heavy tolls from time to time.By about one thousand years ago the human population had only grown to around 300 million, give or take perhaps 50 million. That is about the current population of the United States, but it represented the end result of 159,000 years of human population growth. Slow growth continued until the Industrial Revolution, which began in the 18th century, raised Earth’s carrying capacity again and set in motion a period of modern population growth that continues today, though at a rate that has slowed considerably from that in the late 1960s.
Around 1830, after 159,830 years, the human population reached its first billion. Since then, however, our growth has been unprecedented. During the 20th century the world’s population nearly quadrupled, from 1.6 to 6.1 billion, and since 2000 we’ve added another half billion or so to planet Earth, bringing our numbers to around 6.63 billion. Currently, we add close to another 80 million people each year.
We might describe this sudden and vast increase in human numbers as “irrational exuberance.” After tens of thousands of years, we suddenly, in less than two centuries, have increased our numbers more than six-fold. As Russell Hopfenberg (among others) has noted, “Increases in the population of the human species, like increases in all other species, is a function of increases in food availability.” As Descartes could have noted, “I eat, therefore I am.”
This rapid growth in our population could only have occurred with a vast and rapid improvement in productivity in agriculture. In turn those productivity increases have come almost entirely from our use of fossil fuels, primarily petroleum. If you looked at graphs of population growth and crude oil production side by side over the last 200 years, you would see enough similarity to convince you that it is not coincidence.
Our rapidly expanding numbers and use of fossil fuels have brought us to where we are today, and leave us wondering about the future. Even as we’ve substantially increased greenhouse gases in the atmosphere, including CO2 and CH4, we seem to have reached a broader threshold. Global warming; acidification of the oceans; overfishing; fresh water scarcity; accelerated species extinctions; disappearing wetlands, tropical forests, and other habitats; the growing possibility that we are at or close to a peak in world crude oil production–these may all be signs that humans have now reached or exceeded Earth’s carrying capacity for our species. As eminent ecologist Garrett Hardin warned us, “The universe may or may not be infinite, but prudence demands that we assume that the portion practically available to humankind is finite.” Iconoclastic economist Kenneth Boulding put it this way, “Anyone who believes that exponential growth can go on forever in a finite world is either a madman or an economist.” It may be time to see that our numbers, combined with our expanding affluence and constant need to consume more of everything, have become Earth’s real problem.