The twenty-ninth day

When I was in college the text book for my class on population dynamics began with the riddle:

A man has a lily pond in his garden which keeps getting more lily pads in it. Every day the number of pads doubles. The man knows from experience that in 30 days the pond will be full of pads, and he doesn’t like that so he trims it before it gets to that point, say when it gets about half full. So when will it be half full?

The answer, of course, is on the twenty-ninth day. In that last day the pond will increase by as much as it has increased in all days before that.

Our minds do not intuitively accept the dynamics of geometric growth. Somehow it seems reasonable that the pond should be half full on the fifteenth day. We intuitively feel that we will have plenty of time to deal with problems posed by population growth — because, well, we’ve been increasing our population for hundreds of thousands of years, surely we’ll have another hundred thousand or so before things get critical.

But that isn’t the way geometric increase works.

The sad thing about population crashes is that up to the last minute the culture appears to be flourishing. The population will be highest, and the ability to achieve results at its greatest right before the collapse. This is true for fruitflies in a glass bottle. It was true for humans on Easter Island.¹ It is almost certainly true for us now.

There are several ways a population can exceed the carrying capacity of an ecosystem. It can consume more resources than the ecosystem can supply, or it can produce more waste than the ecosystem can dispose of.

Around 1900 farmers were getting worried because the need for organic fertilizer was outstripping the supply. The invention of artificial fertilizer solved this problem — but the artificial fertilizers we make are based on non-renewable resources, and eventually we will run out. In a sense the global human population exceeded the earth’s carrying capacity about 100 years ago. We’ve been living on borrowed time since.

In 1858 the Great Stink almost closed Parlement, and forced London to stop dumping sewage into the Thames, and instead to pipe it into the estuary and the Atlantic Ocean. When our waste overcame the carrying capacity of the area, the solution was to dump it further afield.

As time progresses we find more resources that we absolutely need, and more wastes that we generate. As our population increases we touch more areas of the planet and there is no longer a safe place to dump our waste. Food remains a danger, especially as we now divert food production to biofuels. Energy has become a need, and the growing scarcity of oil is shown in the recent cost increases (and concomitant increases in the price of food as we try to grow more oil — to my mind a silly attempt that will do almost nothing for providing energy while destabilizing nations).

Our plastic throw-aways are destroying boobies on remote islands where man has barely set foot. Mercury is disrupting the ocean food chains. DDT has send many species to the brink of extinction. And we are slowly coming to see just how dangerous global warming will prove.

If there were only 1 billion of us, trying to live with technology of 1900 — and we didn’t increase that — we might survive. If there were only 50 million of us trying to drive modern cars we might survive.

But the horror of geometric increase is that it isn’t clear that there is a problem until it is far too late to do anything about it.

Then after the last day, when things really are unraveling, history suggests we will go to war over the last crumbs of resources, and by our own hands worsen the crisis we have imposed on ourselves.

We just are not willing, any of us, to reduce our consumption, nor to reduce our baby production, nor to commit suicide. Keeping the economy growing is the watchword of politics; even knowledge of contraception is considered immoral by far too many of us, and suicide is a sin.

We don’t know how quickly the damage we have done will destroy us. But there are so many ways we have damaged the world. And we aren’t addressing any of them effectively. Perhaps, as Kornell suggests, only Alaska will be habitable by 2100, or maybe 2050, or maybe 2150. Who knows when.

But soon.

And unavoidably something will collapse.

(I don’t see much point in voting tomorrow; I will, but nothing important can change)


¹See Jared Diamond’s Collapse: How Societies Choose to Fail or Succeed


One Response to “The twenty-ninth day”

  1. Adger Says:

    Analysis is right on the money. Population is and has been the key always. Pity we gave up on freaking out about it in the 1970s.
    But, if you don’t vote, you may not complain; I keep looking for anyone (even Ralph Nader) to say that overpopulation is THE problem. They’re all quiet. I’ll vote too, but I’m not excited.

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