Our optimistic editor Joe Weisenthal just posted a chart that is supposed to calm anyone worried about global overpopulation.

Modern science has made agriculture so efficient, Joe points out, that corn crop yields per acre have soared 260% over the last 50 years.

The implication?

Our food production productivity is growing so much faster than global population that all the people fretting about over-population are just a bunch of ninnies.

Ah, but the devil's in the details.

Take a close look at that chart, and what you'll find is that the rate of growing productivity has slowed dramatically in the past couple of decades, to the point where it is closing in on the population growth rate.

This chart from Jeremy Grantham's treatise on how we're headed for a crisis of biblical proportions tells the real story. (This chart shows crop yields for a variety of crops, so it's possible that there's something special about corn. But I doubt it.)

It shows that the growth of crop productivity and the growth of population have gradually converged over the past few decades... and that the lines might be about to cross.

And you don't need to have a PhD to figure out what happens if they do cross.

On a finite planet, with finite supplies of fields and finite supplies of raw materials for fertilizers, we cannot continue to make enough food to feed an infinite population. So the only question about overpopulation being a problem is not if, but when.

SEE ALSO: GRANTHAM: We're Headed For A Crisis Of Biblical Proportions