|South-East Asia's Environmental Future: The Search for Sustainability (UNU, 1993, 422 pages)|
|Part I - The driving forces of change|
|2. Population growth in south-east Asia: Pushing the limits|
A focus for discussing the impact of population growth is the expanding evidence about the association between increasing population densities and environmental degradation. Rapid population growth not only diminishes available dietary energy from food supplies on a per person basis but also jeopardizes the maintenance of present food-production levels. Brown and Postel (1987: 4) state: 'A frustration paradox is emerging.... Efforts to improve living standards are themselves beginning to threaten the health of the global economy. The very notion of progress begs for redefinition in the light of intolerable consequences unfolding as a result of its pursuit.'
There are specific examples of environmental deterioration in areas of rapid population gain. Nearly two-thirds of the 1.5 billion hectares of cropland worldwide has been brought into cultivation since the mid-1800s with a corresponding shrinkage in grasslands, wetlands, and temperate and tropical forests (Repetto, 1987: 14-15). Half of the globe's wetlands may have already been lost.
As population pressure pushes cultivation from plains and valleys into the hills, an estimated 160 million hectares of upland watersheds in tropical developing countries have been seriously eroded. On the island of Java, which contains some 60 per cent of Indonesia's total population, Birowo and Prabowo (1986) estimated that soil-erosion rates ranged from 3 to 20 or more times greater than in other parts of the country. Sediment concentration in the river basins has been assessed as from 2 to 10 times as great.
With population densities intensifying, cultivated areas tend to extend outwards and upwards-from the high-yielding lowlands into the less productive upland soils, formerly grazing or forest lands. Lower yields from these fields discourage investments in necessary conservation measures, such as check-dams or terracing. The situation is frequently aggravated by land fragmentation- another indicator of population pressure-which makes it difficult to co-ordinate conservation activities even within a single watershed. In poverty-stricken countries, public funds are spread thinly to provide services and employment for ever-increasing urban dwellers.
Pressure on Resources: 'Carrying Capacity'
Questions have been raised concerning the longer-term capability of resources within specific political boundaries to sustain present or projected population numbers. One approach-borrowed from the field of biology on the maximum population sustainable within a habitat is the concept of carrying capacity, that is, linking population with the local natural resource base. A very ambitious attempt (Higgins et al., 1984) to measure the carrying capacity of the entire developing world (except for East Asia) was undertaken by the Food and Agriculture Organization (FAO) in collaboration with the International Institute for Applied Systems Analysis (IIASA) and supported by the United Nations Fund for Population Activities (UNFPA). The study sought to estimate food-production potential in each soil/climate zone for 15 major crops at 3 different levels of farming practice: low-input, subsistence agriculture; intermediate agriculture, with the introduction of modern technology, conservation measures and improved cropping patterns; and high-level agriculture equivalent to farming practices in industrialized countries. The maximum population sustainable by each country's food output was established on the basis of average caloric and protein intakes, jointly recommended by the World Health Organization (WHO) and FAO in 1973. The projected age and sex distributions of the population at two time periods, 1975 and 2000, were not taken into account in calculating national requirements.
Such a study has several limitations (Hendry, 1988). First, the calculations were not based on economic analysis. Secondly, no allowance was made for cropland to provide livestock feed or to produce non-food cash crops. Thirdly, the elimination of inequities in intra-country food distribution, which would increase average food requirements, was not taken into account in the calculations. Lastly, no consideration was given to other national resources or to the potential role of trade. Brookfield (1992: 28) contends that despite the masses of data utilized, and given the considerable amount of resources available to it, 'the methodology differs little from that of the early carryingcapacity calculations of the 1960s.... As a statement about "carrying capacity", this one-based on a one-sector, closed-economy model-merely reveals the impossibility of determining or even conceptualizing what it is in a real, independent world.'
More intensive use of land and water resources to meet demands from rapidly swelling populations for heightened food production, manifold industrial purposes and diverse domestic uses carries implications for the sustainability of these resources. Evidence exists which points to the severe stress placed on resources needed for food production in many regions: advancing deforestation, soil degradation and desertification. Population increments are not the only cause-poor land management, poverty, inappropriate technologies and other factors also contribute. Blaikie and Brookfield (1987) showed that degradation can arise under both high and low population densities, and under both poverty and affluence, while restorative management can also occur in all these circumstances. According to Brookfield (1992), swelling numbers of people account for only a part of the damage now being perpetrated on increasingly larger portions of the environment. The greater mobility of people and their activities, their enhanced means of inflicting harm through simple innovations such as the chain-saw, as well as all the modern industrial tools, are also partly responsible. Brookfield contends that rising numbers constitute a major element in the damage, but do not form a sufficient explanation in themselves.
But population density is not always a reliable indicator of the pressure upon resources. While it may be true that increasing population pressures have contributed to the shortening of fallow periods and to the removal of forest cover, simply calculating the density per square kilometre does not explain the population-resources relationship sufficiently. Two factors may decide how much damage a person wreaks upon his environment. One is lifestyle: how much that person consumes. The other is the kind of technology used and how much damage or waste it creates. Population size fixes the number of persons and, thus, the total level of damage. To illustrate, population growth is responsible for a greater share of deforestation than commercial logging or ranching. Much of the forest that has been cleared in developing countries has become cropland for expanding populations that cannot be accommodated on existing farmland. These populations may be responsible for more than 80 per cent of the loss of forest cover.
Poverty, of course, is partly to blame for soil erosion. Poor peasants cannot buy fertilizers or pay for the conservation measures needed to protect the soil; and population growth forces farmers to exhaust the soil or to use marginal land. Unchecked soil erosion could cause a drop of close to one-third in food production from rain-fed cropland. This is clearly a direct danger to human life in developing countries.