Many people still suppose the world will wallow and drown in over-population, unable, Malthus-style, to keep pace with the footprint they will leave upon it. Population is my fifth good thing.
Some people in environmental lobbies seem to treat people as a kind of pollution. Although happy to see plants and other animals proliferate, they seem to regard humans as a kind of blot on an otherwise 'natural' landscape. Human beings affect the planet, and always have done. Our hominid ancestors undoubtedly caused mass extinctions with their efficient hunting techniques, and our predecessors changed the appearance of the planet as agriculture developed. More recently our industry and transport systems have changed it.
We are told by some that the Earth cannot support its projected population, having neither the food, the water, the energy or the space to sustain it. None of this is likely to be true. Just as the Green Revolution transformed agricultural output in the 20th Century, so can genetically modified crops transform food production in the 21st Century. New techniques for water purification are developed almost annually, and the Earth is not short of water to treat. Gas will supply abundant energy for decades, and following close behind it is the steady reduction in the cost of photovoltaic power. And human beings, though they are found in every habitat on the surface of the Earth, occupy only a tiny fraction of its area.
As nations become richer, their people no longer need large families to supplement the family budget and to support them in old age. Population levels off as the world becomes wealthier, and is unlikely even to approach the levels touted by alarmists.
In fact human beings are as asset, not a burden. Their creative intelligence has created opportunities for many people to live more rewarding lives well above the subsistence level that was the lot of their predecessors. Human ingenuity and technical skill have given us wonderful cities in which to interact and co-operate with our fellow humans. Their intellect and creativity have given us buildings that lift the spirit, literature that inspires, music that elevates the soul, and paintings that convey insights into the human condition.
Humankind has faced problems and has used its ingenuity to solve them. It finds ways to make resources go further, fields to produce more crops, engines that are cleaner, and advances in transport and communication that shrink the world and enable us to interact with more of our species. Julian Simon described the human imagination coupled to the human spirit as "The Ultimate Resource."