I am a very staunch "pro-life" advocate, but the biggest threat to life on this planet is the over population of the human species. I just can't buy the argument that humans have some innate right to survival at the expense of all other species. Yes, our growth rate is slowing, but it's not enough.
There's an old example used to illustrate where humans are on our population trajectory. You've probably heard this before, but to review: you have a jar with two microbes, and the net growth rate of the microbes is such that the total number of microbes doubles every minute (factoring in both birth and death rates), and the jar is just big enough so that it will fill to the brim with microbes in one day. So you put the two microbes in the jar at midnight, and the jar is full at midnight the next day. The crux of the example is that at one minute before midnight, the jar is half full. Two minutes before midnight the jar is a quarter full, and three minutes before midnight the jar is only an eighth full.
Ok, it's not a perfect explanation - humans can not completely "fill up" the world and there are numerous other factors not taken into account. But most scientific interpretations of this scenario put our current "population time" at 11:55. Five minutes till midnight. Here is a graph that shows our historic worldwide population growth:
Humans were supposedly advised to "go forth and multiply". Some 2,000 years ago that was fair advice - but now we're killing the planet. We need to stop. Many projections say that the global population will level out at around 10 billion people, as we won't have enough food for any more. That's just great - we keep popping out babies until everyone is starving and in abject poverty. Swell.
The truth is, even if we managed to completely HALT the growth rate and maintain the current global population, we would continue to cause the extinction of many other species and eventually use up all the global resources we have become dependent on. We are poisoning the oceans, cutting down tropical rain forests at a dizzying rate, and drilling every last drop of oil we can find. And while farming technology has kept up with the population growth, and we can produce an amazing amount of crops per acre, we are also polluting the planet with petroleum based fertilizers and toxic insecticides.
Global population was a big issue in the 70's when it suddenly dawned on everyone that we are headed for disaster. Now it's old news and no one wants to hear it anymore. It's just another "unsolvable" problem like the national debt, which we will dance around forever because the solutions are very politically incorrect.