I too am an optimist. I believe in the capacity of the human species to answer the call of necessity with ingenuity and compassion. But I am also a realist. And as I watch the children of Nadi village play soccer in the Pacific twilight, I acknowledge sadly that their future is already heavily mortgaged, their freedom of action already constrained by the mathematics of population growth. For while we may have slowed the population snowball somewhat, it is still rolling, and as it rolls, it grows larger and more threatening, augmenting its mass and potential impact even as it seems to grind to a standstill statistically.
Numbers are one thing, quality of life is quite another.
On the environmental level, we have yet to feel the full effect of past population growth, much less of our efforts to curtail it. We are already consuming half of all accessible fresh water on Earth. We are already farming most of Earth's available farmland. Land under cultivation is increasing, but only one-eighth as fast as population, and barely enough to compensate for land lost to exhaustion or desertification. We are still emitting greenhouse gases at an alarming rate.