I'll try to play nice
I'll agree that almost all of our problems are due to population. However, I'll also make the argument that the solution to those problems will come from our population "problem". How? Human ingenuity. More people equals more minds equals more human horsepower available to solve problems.
Now, of course we can't just breed like bunnies and assume everything is going to be rosy, people are going to have to be actively engaged in order to contribute to the solving of our problems (we can't have them eking out a life on a patch of dirt). Enter globalization and development. Take China and India as an example. There's 3.5 billion people that are entering the global community - this very well may be a watershed moment for the earth. Never before, and likely never again, will so many people become actively engaged in the global community at one time. These people, and their children will become educated and will help move our species forward. How many Hawking's, Einstein's or Newton's will we find in 3.5 billion people? I don't want the next Hawking to spend his/her life in a rice paddy. With all 6 billion souls (stabilizing at 9 billion) pushing the human race forward, I don't doubt that we can accomplish some amazing things.
Optimistic? No doubt.
Regarding the China quote
The only country that has successfully confronted the issue, the People's Republic of China, was universally condemned for doing so. And today is sitting on top of one trillion dollars in cash, a booming economy, and it should surprise no one.
You can't make the argument that reducing population is good for an economy (or at least use China as evidence of that). China has 1 trillion in reserves and a booming export economy because a dirt cheap labour pool of 1.3 billion people is being exploited, it has nothing to do with the 1 child rule. China is a whole whack load of agrarians moving to manufacturing labourers - so in a sense, manufacturing (which is what is driving China's success), is seeing a large increase in the population of available workers.
China's one child policy will come back to hurt them - but it will be in a generation. China realizes this, and they even have a name for it. Google the "4-2-1" problem, where 1 child will need to support 2 parents and 4 grandparents. Some real significant issues come along with that. This is also the reason why the scaremongers have got it wrong in regard to some hypothetical West/China armed conflict. China can't afford to lose it's young - they're too valuable.
