With the population doubling every couple of generations, and our petroleum-based food supply on the downward slope, things are about to get ugly unless we voluntarily start having one or fewer children immediately
“The greatest shortcoming of the human race is our inability to understand the exponential function.” Al Bartlett
Population overshoot occurs when a population temporarily exceeds the long-term carrying capacity of its environment. The result is a sudden, unexpected, population collapse or die-off.
Overshoot often occurs when a species’ natural predators are removed from the environment (think wolves and deer), causing the species to multiply rapidly, over-consume their food supply and then suddenly experience mass starvation.
Having eradicated the vast majority of our predators, humans may have outsmarted all other species on Earth, but can we outsmart Mother Nature?
Too smart for our own good?
For hundreds of thousands of years humans lived in balance with all the other lifeforms on Earth, until about 12,000 years ago… when we learned to cultivate grains and domesticate animals. The dawn of agriculture, represented the dusk of sustainable human existence.
Agriculture gave humans a false sense of food security — temporarily pumping out more food per acre — and encouraged us to go forth and multiply. But once we stripped the soil, we had to migrate farther and farther around the world, leaving deserts and collapsed civilizations in our wake.
The plow had already destroyed most of the Earth’s topsoil by beginning of the 20th century. If not for the Green Revolution — the innovation of using fossil fuel for fertilizer — many scholars believe the global human population already would have collapsed.
While petroleum has allowed the baby boomer generation to double a couple more times, the late physics professor Al Bartlett warned that once the fossil fuel runs out we will likely have no new technology in place capable of supporting the massive population it created.
In a famous lecture, he explained how the “smartest” species on Earth has overlooked a simple mathematical principle — exponential growth — that will likely lead to a massive population collapse — the sudden death of billions of people — in the next few decades:
The population bomb is ticking
The problem is people think of population growth in linear, rather than exponential, terms, he said.
Considering we’re living in the middle of the Earth’s sixth mass extinction crisis, most scientists acknowledge we have already far exceeded the Earth’s carrying capacity for humans. But Bartlett’s math should convince even those who believe the population can continue growing indefinitely.
If you’re one of those people, how many people do you think the Earth can support? Can we agree that 15 billion is too many?
(If not, let me quickly convince you that it is. In a little over a century, we’ve used up about half the Earth’s oil supply with a population less than half of that size, and modern agriculture is entirely dependent upon oil.)
Supposing we agree that 15 billion is too many, how long do you think it would take us to arrive at such a number if it were possible to continue at our current growth rate of 1.12 percent?
It’s taken us about about 12,000 years (since agriculture) to get to our present population of 7.5 billion. (We hovered at just over 5 million for hundreds of thousands of years before agriculture). Will it take us another 12,000 years to get to 15 billion?
No. If our current growth rate could continue, it would take us 50-60 years, or two generations.
This is because of the exponential function.
Are humans smarter than bacteria? Will we be the only species capable of anticipating and avoiding population overshoot and collapse?
Like humans, bacteria populations grow by doubling. Bartlett asked us to imagine we put one bacterium in a Petri dish at 11 am and the number doubled every minute. By noon the dish is full.
“At what point was the dish half full?” Bartlett asked.
The answer is not 11:30.
“If you were a bacterium,” Bartlett asked, “at what time would you realize you were running out of space?
If you were only half full at 11:59 and it took you almost an hour to get there, you might think you had another hour to figure things out, but you don’t. You have less than a minute, and you probably won’t realize that until a few seconds before noon.
Bartlett’s point was, by the time most species realize they’ve exceeded their environment’s carrying capacity, it’s too late. Their food supply is gone. The only way to correct the overshoot is collapse.
Just for fun, Barlett asked us to imagine it were possible for the bacteria to find three new Petri dishes full of sugar water (or in our case three new planets) to occupy just in the nick of time. What time would they be full? 12:02.
“Zero population growth is going to happen,” Bartlett said. It doesn’t matter if we like zero population growth or don’t like it. It’s going to happen.”
“Modern agriculture is the use of land to convert petroleum into food,” Bartlett said.
He was right. We are dependent on petroleum and petroleum bi-products not only for soil fertilization, but for ever aspect of food production and distribution.
Keeping this in mind, let’s talk about how soon peak oil is going to affect population.
“What time is it when the remaining reserve of oil is equal to what you’ve used in all of history?” Bartlett asked.
“One minute before 12.”
Peak oil in the US was in 1970, with a partial recovery from the Alaska pipeline near, which peaked in 1990, Bartlett said. By 2000, we recovered 3/4 of the recoverable oil that was ever in our ground. By 2003 we were in Iraq.
Bartlett estimated oil world oil would peak by 2010. According to the International Energy Agency, it did, in 2006.
Even if there were twice as much oil as estimated in the earth, which is unlikely, Bartlett said the peak would come by 2030.
What will life be like on this Earth when we have oil production declining in unison with population growing? Bartlett says not pretty.
A Pyschology Today article paints the picture with two gruesome examples:
In 1944, 29 reindeer were brought to St. Matthew Island. Initially food was abundant, and because there were no predators to keep it in check, the reindeer population increased dramatically.
In just 20 years, the population reached a peak of about 6000 and then collapsed. A sudden, massive die-off brought the population back down to 42. 99% of the reindeer died of starvation within two years of peak population.
In case you’re thinking humans are smarter, let’s look at what happened on Easter Island.
According to anthropologist and ecologist Jared Diamond, Polynesian agriculturalists overpopulated the island a few hundred years after arriving on it.
The first Polynesian explorers landed on the island around 700 CE. Deforestation and agriculture were well underway by 800 CE. Population is estimated to have peaked at around 20,000 around 1400 CE then and collapsed to less than 2000 by around 1700 CE. The survivors resorted to cannibalism and hiding in caves.
How can we avoid mass starvation and collapse globally? Stop having children now! Or at least no more than one child per couple on average!