## Humanitys Footprint

According to United Nations' statistics, there were, as of July 2007, some 6.6 billion people alive on Earth. It is perhaps worth seeing that number in all of its mathematical glory: 6,600,000,000. If the names of each of these people were written on individual sheets of paper, then the resultant book of humanity would be a weighty tome 660 km thick (assuming each page is one-tenth of a millimeter in thickness), and, of course, by the time the first few pages of this great book of life had been filled in, the book would already be out of date, since something like 100 people die naturally every minute of every day of every year at the present time. To counter-balance this sad but necessary and inevitable end of life, of order 240 new human beings enter, kicking and screaming, into this blooming and buzzing confusion of a world per minute. Indeed, the number of human beings is growing at a rate of about 75 million new mouths to feed per year.

In Table 3.2 it was revealed that the area of land where humanity might permanently live amounts to some 149 million square kilometers. Let us imagine that all of humanity decides, for no particular reason, to come together and form one giant group hug. What then might the size of the field required to accommodate all of humanity be (as of July 2007)?

This, in fact, is a very simple calculation. If we assume that each human being occupies a 1-meter square area, then to enact the group hug a total area of 6.6 billion square meters will be required. Converting the field area into square kilometers, all of humanity (with each person having 1 square meter of ground) could fit into a square field having sides of 81.2 kilometers—an area not much larger than greater London in the United Kingdom, or metropolitan New York in the United States! Humanity, in all of its bodily form, occupies an area of a mere 6,600 square kilometers. This is of order 0.004% of the Earth's landmass (or about 0.001% of the entire surface area of the Earth).

Thus, human beings as entities do not take up much room on the Earth; our literal footprint is very small. The problem, of course, with the calculation just performed is that human beings need more than 1 square meter of land upon which to live. The house in which this author lives, for example, is about 10-meters square, and this area is purely for moving about in. No food, electricity, or water is grown or generated within the house. Let us look at just one facet of what lies behind this great luxury.

The electricity consumed in the author's house is generated by SaskPower, a Saskatchewan Crown Corporation with assets amounting to some \$4.2 billion (according to its 2006 annual report). SaskPower employs in excess of 3000 people, operates three coal-fired power stations, seven hydroelectric stations, four natural gas stations, and two wind turbine facilities. A generating capacity of over 3000 megawatts is achieved, and power is supplied to more than 445,000 customers over a grand total of 155,000

kilometers of power lines. Now, clearly all this investment in generating electricity is not for the author's benefit alone, but it begins to give some idea of the massive infrastructure that surrounds the life of one person in one of the least populated provinces of Canada.

Although in Canada, the United States, and most of Europe people have great expectations and can simply assume that there will always be electricity, drinking water, sewage treatment, garbage removal, and food to buy in stores, the vast majority of people in the world have no such expectations or luxuries. This poverty reduces the impact of Homo sapiens collective footprint upon Earth, but nonetheless there is literally nowhere on Earth where the presence of humanity, either by alteration or habitation, isn't felt.

At the present time, something like 50% of humanity lives within the confines of large cities and sprawling urban areas of enhanced population density (measured as the number of people per square kilometer), and these regions alone cover about 1.5% of the Earth's landmass. This constitutes a staggering 2.2 million square kilometers of bustling roadways, industrial complexes, houses, hospitals, and humanity all compacted together in a syner-gistic frenzy of life, work, economics, and politics. Indeed, the area of this urban sprawl is 340 times larger than the entire human footprint area of 6600 square kilometers (our collective group hug number) derived earlier. On a geographical scale, the combined urban sprawl of humanity would just about cover the entire country of Algeria (see Figure 4.11). The hyperextended, metaphorical footprint of humanity is indeed, both very long and very broad.

Figure 4.11. Algeria is the eleventh largest country in the world, and has a surface area of 2.4 million square kilometers (about 3.5 times larger than that of Texas). If all of the world's cities and towns were joined together in one sprawling mass, they would cover an area comparable to that of Algeria, and in this region, half of humanity would be housed.

Figure 4.11. Algeria is the eleventh largest country in the world, and has a surface area of 2.4 million square kilometers (about 3.5 times larger than that of Texas). If all of the world's cities and towns were joined together in one sprawling mass, they would cover an area comparable to that of Algeria, and in this region, half of humanity would be housed.

At the beginning of the twentieth century, it is estimated that 10% of the world's population lived within large towns and cities. By 2020, it is estimated that 60% of humanity will live in urbanized areas. Although cities certainly provide people with many conveniences, such as jobs and entertainment, they produce none of the key elements, specifically food and water that human beings need

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Figure 4.12. ''Square Earth'' shows the relative proportions of land area to oceans and the relative area of cultivated land, extreme desert (unfit for producing food), and tropical rain forest. Water covers 70% of the Earth's surface, and of this 97% is within the oceans, with only 0.6% being in the form of drinkable water. The 1-unit side measure corresponds to a distance of 22,585 km.

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Figure 4.12. ''Square Earth'' shows the relative proportions of land area to oceans and the relative area of cultivated land, extreme desert (unfit for producing food), and tropical rain forest. Water covers 70% of the Earth's surface, and of this 97% is within the oceans, with only 0.6% being in the form of drinkable water. The 1-unit side measure corresponds to a distance of 22,585 km.

in order to survive. To feed the 6.6 billion peoples that presently reside on Earth, of order 22 million square kilometers of land (about 15% of the total land area available on Earth; see Figure 4.12) are estimated to be under continuous cultivation. This may seem to indicate that there is plenty of additional land that might be turned to food production, but this in fact is not the case. Much of the world's surface is completely unsuitable for growing crops of any kind. Extreme hot and cold deserts (i.e., the Sahara Desert and Antarctica) account for about 16% of the Earth's land area; rain forests account for another 15%, while boreal and temperate forests account for a further 25% of the area. Even if humanity was foolish enough to cut down and destroy all of the forests in the world, there would still be little hope of feeding the growing numbers of people that will be born in the next 40 years. Indeed, by 2050, it is predicted that the global human population will have swelled to some

9 billion people. The question that looms large and clear now is, ''Can the world support so many hungry mouths along with their bulging cities, extended agriculture, and the billowing smokestacks of their associated industry?''

The Reverend Thomas Malthus (1766-1834) was perhaps a rather pessimistic man, but he understood human nature. He is best known today for his An Essay on the Principles of Population Control, published in 1798. The Essay is primarily concerned with ideas surrounding ''the future improvement of society'' and Malthus is specifically writing at odds with many of his contemporaries who felt that there were no limits to what future societies might achieve. The problem as Malthus saw it was that ''the power of population is indefinitely greater than the power in the earth to produce subsistence for man.'' In this claim, Malthus is essentially saying that a population that keeps on growing will ultimately exhaust the capacity to feed itself, and that once the limit of the food supply is exceeded, then the population must plummet—a situation often described in prosaic modern-day language as a Mal-thusian meltdown. The problems associated with unchecked population growth are nontrivial, and are further discussed within Appendix 4 at the end of this book.

From a terraforming- or space-colony-living perspective, this question has very definite relevance, since these domains are, just like Earth, finite with respect to both size and resources. In his pioneering book The High Frontier, Gerald O'Neill argued that ''the population density in the space habitats will be governed by sheer economics____A key element in the humanization of space will be the unchecked continuation of the industrial revolution, the process by which average individual productivity and wealth increases.'' It is unnerving to realize how utterly wrong in thinking an otherwise far-sighted physicist can be. Current short-term economic practices and unchecked industrial growth will never provide a satisfactory platform for the human colonization of space— that is, if the colonization of the Solar System is to be for the greater good of all humankind. It is in this sense that we, all the peoples of Earth, had better learn how to live within the limits set by a finite system before the colonization of space and the terraforming of the planets begins. Before we terraform other planets, we will first have to transform ourselves.

It might well be that humanity's immediate future on planet Earth is looking decidedly bleak, but the key point is that we know what is happening, and we can potentially do something about it. It is our call. We know what might potentially happen in the future, and humanity does have the intelligence and hopefully the will to save itself. If we don't believe this then there really is no hope. Terraforming will eventually allow humanity to expand into the Solar System, but it is no quick-fix answer to the present-day problems of an overexploited Earth. Humanities' near-term goal must be to live within the finite limits set by its surroundings, and perhaps remarkably, to this end, there is hope for us.