It’s the maximum number of individuals of a particular species that a given area can maintain indefinitely. When you calculate carrying capacity, you generally do it for a particular species–bear, cougar, salmon, fire ant, deer, human . . .

Does this concept apply to humans?

What did Thomas Malthus say? We’ll reach carrying capacity and then there will be a crash, because population grows faster than food. ‘Celibacy and moral restraint’ were the keys to avoiding this catastrophe, according to Malthus–have less sex, less kids.

Well, as we know, technology intervened. In many ways–birth control/contraception, food production technologies, high tech fossil fuel-intensive agriculture. And so we seem to be defying any limits that might be put on us by carrying capacity. According to some estimates, we are currently using resources at a rate that would require 3 planets to sustain us in the long run.

Bill Catton was a sociologist/human ecologist at Washington State University, who wrote a book in the early 1980s called Overshoot.

He contends that humans are not exempt from natural laws. Carrying capacity applies to us, too. So why hasn’t it been a problem, why haven’t we seen a major crash in the population? According to Catton, we should think of resources as ‘savings accounts’–if we draw them down at too great a pace, we eventually run out. Sort of like deficit spending, using your credit card without money in the bank.

Non-human species, without technology, aren’t able to defer the overshooting of their carrying capacity.Once, populations were restricted to the resources they could extract from their immediate environment, and if they lived beyond their means, they were likely to disappear. But that’s no longer the case-if it were, the U.S. and other countries couldn’t consume so much of the world’s ‘natural capital.’ Add to this the fact that humans are living longer lives, consuming more resources (than, say, 200 years ago, or even 50 years ago), and we have even greater levels of resource consumption per person per lifetime. Catton goes so far as to suggest that there are really two species of humans–one that consumes at a rate that is consistent with historical records, which we call Homo sapiens. The other is Homo colossus, who consumes resources at a vastly higher rate, and relies on an enormous number of technologies and technological systems just to get through the day. In other words, the difference between rates of consumption for people living in poor, agrarian countries and rich industrialized countries is so great, that we shouldn’t compare them as equals.

Consumption depletes supplies, leads to transformations that often pollute the environment. As Charles Darwin pointed out, when one species dominates, others’ numbers will decline. We have seen extinctions increase in the last century–habitat has decreased as human populations colonize the globe. Something has to give, some species have to pay the price. Here are some of the trends:

• Accelerated deforestation
• Tropics are more than trees–in some ways they’re the lungs of the earth, fixing carbon, yielding oxygen
• Accelerated fossil fuel consumption
• Depletion of reserves
• Accelerated greenhouse gas production
• Accelerated mineral extraction
• Drawdown of reserves (we’d better recycle … re-use … better yet, reduce)
• Accelerated appropriation of water resources

Catton says that humans have already overshot carrying capacity, and the only reason it hasn’t affected us yet is because we’ve been able to rely on resources that future generations would have used–largely non-renewable resources, such as fossil fuels and minerals, that won’t be available in the future to the same extent they are now. We are using up ‘ghost acreage.’ When a society can’t live within its environment, it can seek resources from other environments. Most of our resources we use here don’t come from La Grande, and many come from halfway around the globe. Some also come from ancient ecosystems–carboniferous forests that, through time and heat and compression, have become sources of petroleum. According to Catton, there are no guarantees that humans will stick around. They’ve only been here about 100,000 of the earth’s 6 billion years, after all.

In the great baseball game of life, maybe Mother Nature does bat last . . .