Seven's a crowd

AS census month begins, looking at the extraordinary rate at which humans have increased throughout the planet during our 200 000-odd-year existence makes for a fascinating exercise.

If you thought that the current world population was bursting at its seams, just consider that, at this very moment, the number of people who have ever lived amounts to a confounding 56 billion, according to the thought-provoking blog, http://1000memories.com/blog, whose work has been featured by both Time and Forbes magazines in the past year.

That's eight times more than the total number of people who are living on the Earth right now ... yet 200 000 years ago, only 10000 people had ever lived - which just goes to show how our species has exploded in the blink of an evolutionary eye.

But it is since the advent of Christian times that the most rapid expansion in human numbers has taken place. Two-thousand years ago, the world population was only 300 million. By the turn of the 19th century it had already hit the one-billion mark. Just 200 years later - some time later this year, that is - a woman will give birth to the seven-billionth member of the current world population, according to the UN's Population Division.

As 1000 Memories blogger Jonathan Good puts it: "We know that this year the world population will tick past seven billion. We know that there are a whole billion more of us than there were in 1999, as if a new China has appeared out of nowhere." This means that one in eight people who have ever been born are alive at this very second.

"The world population is driven not only by more people having more children, but also the fact that we're living longer. Despite the fact that birth rates have been falling in recent decades, the population has continued to rise as those already on the planet lead longer, healthier lives, thanks to modern medicine and improved nutrition," Good points out. "Until very recently, life expectancy at birth hovered between 20 and 35 years, but now it has risen to 67 years."

But does the bursting world population and overall increase in global life expectancy mean that the planet is overpopulated? With some 50-million people now in South Africa, for instance, are there just too many of us?

Dr Bob Scholes is a CSIR fellow with a special interest in the effects of human activities on the global ecosystem. The global human population might have mushroomed in the last 2000 years, especially since the industrial revolution, but Scholes notes that, "contrary to conventional wisdom, the global population is no longer growing at exponential rates. Societies around the world are undergoing demographic transition, where the birth rate falls to match the death rate. Sub-Saharan Africa is, as yet, the exception, but will get there. The result is that the global population is expected to peak at nine to 10 billion people, around the middle of the 21st century".

That's not to say there's nothing to worry about. According to Scholes, while the global population is expected to level out, there is also a school of thought that claims our numbers are already outstripping the resources available to sustain us.

"Fundamental limits are emerging all over the place in the contemporary period - the capacity of the Earth's climate system to absorb greenhouse gases, the capacity of global soils to support agriculture, the water availability for human use," he says.

But it's also worth considering that it is comparatively small sections of the global population that have been blazing their way through the planet's bounty.

"The average American consumes about 53 times more goods and services than someone from China. The US contains 5% of the world's population but accounts for 22% of fossil fuel consumption. A child born in the US will create 13 times as much ecological damage over the course of his or her lifetime than a child born in Brazil. He or she will drain as many resources as 35 natives of India," Dave Tilford of the Sierra Club, one of the largest conservation organisations in the US, points out.

Perhaps it's the way we are consuming our resources, rather than how many people are consuming them, that is the problem. Perhaps it's not that we're unsustainable, simply that our habits are.

TELL US: Is overpopulation and its impact on the planet a myth? E-mail tiara.greenlife@gmail.com