Do we have overpopulation, and can we bring our numbers down in a humane way--and on time?

[Daniel]

Every year, there are about seventy-eight million more people walking the streets and frequenting the food stores. Every week, a population the size of San Diego is coming online—once those who die are accounted for. Every four years, the equivalent of the entire United States population is added on.
Within a living system that has finite production capacities, it has always been a matter of what we indirectly force out of existence and of when much is too much. Do we really want to win the human race—a human habitat from sea to shining sea standing at the finish line with an unraveled, simplified planetary ecosystem tumbling about our collective ears? Under the already heavily degraded planet, short of reducing our numbers to under a few million, the question would become not whether our presence impinges on the planetary ecosystem but what is an acceptable degree of degradation.
I call on bringing our numbers down to 1 billion people--and I have a fairly good idea what it takes and how fast we can get there.
The short of it is this: Under a two child policy, we would be able to get there around 2175.