Friday, September 24, 2004

Malthus was right—repeatedly

For the critics of the idea that growth has limits, Robert Malthus has always been the ultimate example of the fallacy of limits. In his famous Essay on Population (1798), Malthus argued that unchecked population growth always exceeds the growth of means of subsistence. Actual population growth is kept in line with food supply growth by "positive checks" such as starvation, disease and the like. It is taken for granted that this argument is false since, in the two hundred years since he wrote it, population growth has exploded and technology—and the expansion of growing areas in North and South America—has been able to keep food production growing fast enough to prevent major famines. Many people conclude that there are few if any limits to growth, that technology will always keep food production ahead of population growth.

A look at history reveals that the Malthusian scenario has already happened repeatedly in history. Furthermore, there is a major factor that Malthus overlooked—every major advance in civilization and technology has resulted in a degradation of the environment that has inevitably lowered the ability of that civilization to feed its people. Thus, population overshoots are not a linear progression as Malthus projected, but the result of a scissors action where the total potential production continually declines due to environmental degradation, while the population growth inevitably overshoots the ability of the land to support it.

One of the first environmental changes that appeared with the introduction of the city state and empire was the deforestation of the surrounding region. Originally, wood was cut as a fuel source for the early city states, but with the coming of the Bronze Age, the demand for wood increased exponentially due to the smelting needs of the metal. Once of the earliest recorded myths, “Gilgamesh” records the cutting of the Lebanon Cedars, forests now lost to history. At the same time, the increasing demands for food lead to the development of massive irrigation systems which increased food production, but at the same time increased the salinity of the soil, and ultimately turned it into desert. Many of the regions where cities first appeared are today arid and sparsely vegetated. Gilgamesh’s city of Ur is now surrounded by a desiccated and largely deserted landscape.

Europe, in the late Middle Ages underwent a similar transformation. Spurred on by technological innovations brought back from the Crusades and the growth of the new wool trade, Europe underwent a major transformation. The period of rapid economic and population growth between 1050 and 1300 saw a transformation of the European landscape form one predominantly forested to one where forests were isolated an fragmented. Landholders encouraged their peasants to open new lands to agriculture that had been woodlands, marshes and moors. New towns and villages sprang up. Between 1100 and 1300, food supply was adequate, but by the early fourteenth century, with little new land available, the increase in production failed. After that, serious famine occurred every ten years or so. From 1315 to 1317 the Great Famine ravaged northern Europe. From the 1320s, crop failures struck Italy. Famine struck in 1329. Softened up by famine, the European population was decimated by the Black Death which struck between 1347 and 1351. For some parts of Europe, recovery was a long time in coming. In 1850, Tuscany still had two million fewer people than it did in 1300. Given its technological level, Europe had experienced a classic overshoot.

The Polynesian expansion onto the Pacific Islands provided some very dramatic examples of population overshoots. While some islanders learned to live within the limits of their island ecology, others destroyed their environment and suffered disastrous consequences. Pitcairn Island was abandoned while Easter Island was entirely deforested, and native species hunted to extinction, resulting in a disastrous loss of population. In parts of New Zealand, archeology has provided evidence of malnutrition and economic decline.

The industrial age has provided the greatest opportunity for population increase in history. The Green Revolution has fed billions of people. Technology has been so successful that Malthus has appeared to have become outdated. But recent years have brought evidence that Malthusian theory and the limits to growth, were only postponed, and not negated. Food production no longer keeps up with consumption. Water tables are declining steadily and deserts advancing. Energy supplies are straining to keep up with demand and show signs of going into decline. The past two centuries have seen the greatest economic expansion in history, but we are now faced with the possibility that the resulting population overshoot may also be the greatest in history. The twenty-first century may turn into a world wide version of the European fourteenth century.


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