The United Nations Population Fund projected that the world population reached 7 billion people on Oct. 31.
In a world of shortages, violence becomes more prevalent as nations, or smaller groups, seek to provide for their own, Seat observes.
When I was born in 1938, the global human population was under 2.3 billion. So in my lifetime the population of the world has tripled, and then some.
Population Action International has an app on its website that calculates the world population on any given day in the past.
You can put in your birth date and quickly get the estimate of "your number" – the population of the world on your birthday. The link for "What's Your Number?" is here. (I was 2,267,750,937.)
It is estimated that the world's population didn't reach the 1 billion mark until 1804, just a little over 200 years ago.
By 1927, 123 years later, the population of the world became 2 billion. Then in just 33 years, in 1960, the number of people on earth climbed to 3 billion.
Since February 1967, the world population has doubled to reach the 7 billion mark. (Actually, the U.S. Census Bureau says that 7 billion won't be reached until February 2012.)
What will it be like, though, if the population doubles again in the same length of time?
That is unlikely to happen; estimates now indicate that even the 9 billion mark will probably not be reached until 2045 or later. Still, that is a number fraught with problems.
How many people can the earth sustain? It can be argued that the earth is not adequately sustaining its 7 billion people now. But the problem is largely a matter of distribution, not resources.
There is enough food for everyone, but some (particularly many Americans) eat far too much, and hundreds of millions, mostly in south Asia and Africa, have far too little to eat.
The growing population strains other resources, too. And, again, the United States, with only 5 percent of the world population, uses an extraordinarily large share of the world's natural resources.
As the population continues to rise above 7 billion, there will doubtlessly be more and more struggle for limited resources: fresh water, food, oil and the like.
As resources become scarcer, prices rise and more people face financial problems. More troubling, in a world of shortages, violence also becomes more prevalent as nations, or smaller groups, seek to provide for their own.
Population pressures and need for additional food and natural resources have been part of the cause of wars, large and small, through the centuries, and the likelihood of warfare increases as the population continues to increase.
In addition, the gap between the wealthy countries and the poor countries, or between the wealthy and the poor within countries, leads to various acts of revolutionary violence.
So the fact that the world population is now 7 billion and counting is not good news. But that is the situation we are in.
And it is a matter about which we all need to be concerned, supporting ideas and programs for dealing with the problem in constructive ways.
Leroy Seat was a missionary to Japan from 1966-2004 and is both professor emeritus of Seinan Gakuin University and pastor emeritus of Fukuoka International Church. This column appeared previously on his blog.