(This is Part 3 of a series. Go back to Part 2.)
1a. Human population growth
Following the growth of the human population on planet earth is an interesting exercise. To make the numbers and times easier, the following statistics are approximate only, but they are also roughly correct:
For endless millennia we existed like ants upon the seashore, a few forms scattered here and there amidst seemingly infinite tracts of jungles and forests. To reach 250 million people took the human race until roughly the time of Christ in the 1st century AD.
From there, doubling to 500 million people took another 1500 years,to about 1500 AD. To double from there to about 1 billion humans took another 300 years, to about 1800 AD. The next doubling, to 2 billion, only took another 130 years and took place around 1930. We added another billion by 1960 and another by 1974 to reach 4 billion people. Then we added 2 more billion by 1999 and half a billion since then to reach our present level of 6.5 billion.
For countless eons we could be as rapacious as we pleased towards nature and still live "lightly upon the earth," because our numbers were too small to make any difference. But since the Industrial Revolution in 1750 or so, not only has our population been growing exponentially but our economic activity per capita has also been growing at a rapid rate.
The combination, occuring in just the last few generations, has meant that for the first time in history the human species has become a major impact upon the planet.
As just one example, we're now pumping 7 billion tons of carbon into the atmosphere each year. That is significant enough that the density of carbon in the atmosphere has increased from 280 parts per million (ppm) in the pre-industrial era to 380 ppm today.
Moreover, the human population is calculated to grow to 9 billion by 2050. This statistic takes into account the fact that birth rates are falling in developed countries. However, that is more than overwhelmed by the continuing high birth rate, well above the replacement rate, occurring in developing countries.
Thus, while the population of developed countries in 2050 will be about the same as it is now—about 1.2 billion people—the population of poor countries will have increased by some 2.5 billon—from 5.3 billion to 7.8 billion—for a total of 9 billion people on the planet in 2050.
Now consider that the U.S., which consumes about one-quarter of the fossel fuel in the world and creates about one-quarter of the greenhouse gases, has 148 million cars at present, while China has 19 million and India has 9 million. What happens by 2050, when China is projected to have 514 million cars and India is projected to have 610 million?
Answer: A devastated planet, if we stay on current trends. And that's just in one area. As developing countries like China and India and others, with some justification, demand to industrialize to the same extent as the West, the amounts of various metals and toxins in our rivers, lakes, oceans, soil and so on are projected to double or even triple from here by 2050.
Meanwhile, our pumping of carbon into the atmosphere is projected to double to 14 billion tons annually, taking the density of carbon in the atmosphere to about 550 ppm, about double the pre-industrial density. Not coincidentally, that is the realm where scientists' various climate models begin to predict non-linear and catastrophic consequences.
(This is the end of Part 3. Go to Part 4.)
—jim sloman, 11.29.06
|
