JUST HOW far is the growing population to blame for the environmental problems we face today? A furious debate rages around this subject – and it is not just an academic sideshow. For it provides ammunition for and against the most contentious issue in development: family planning.
In one corner stand the neo-Malthusians, who blame most of the developing world’s ills on population growth. They include groups such as the Population Crisis Committee in the US and individuals such as Prince Philip. The basic logic is simple and apparently convincing: more people consume more of every kind of resource, from energy to land to minerals, and produce more waste.
In the other corner: anti-Malthusians, such as the environmentalist Barry Commoner and Frances Moore Lappe, an American writer on agriculture. They blame, variously, inappropriate technologies; overconsumption by the affluent; inequality and exploitation, which squeeze poor farmers onto ‘marginal’ land and ‘force’ them to overexploit it. They blame everything, in fact, but population growth.
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This highly polarised debate is not scientific, but ideological, fuelled by politics and religion. The Malthusian side provides support to those who favour drastic ‘population control’ programmes – as in India in the mid-1970s, which after a period of enforced sterilisations alienated people from family planning. The anti-Malthusian arguments back up those who wish to deny women the right to a free choice of family planning and other improvements in their position.
Neither side can win the debate because both arguments are oversimplified. Both sides must accept that population is one, but only one, of the factors that lead to degradation of the environment.
There are three key factors. The first is the level of consumption, determined by lifestyles and incomes. Second, the technology needed to satisfy that consumption, and dispose of the waste generated. These two factors together decide how much environmental damage is done per person. Multiply by the third factor, population, and you arrive at the total level of damage.
Take carbon dioxide, the most important of the greenhouse gases. Worldwide emissions rose from 2349 million tonnes in 1950 to 6793 million tonnes around 1985, an increase of 3.1 per cent a year. Over the same period world population grew by 1.9 per cent a year. Emissions per person rose by 1.2 per cent as a result of changes in technology and higher consumption of goods that involve production of carbon dioxide.
Population growth thus accounts for almost two-thirds of the increase in carbon dioxide entering the atmosphere between 1950 and 1985. Increases in consumption and in technology together account for a little over a third.
If present trends continue, the future impact of population growth on emissions of carbon dioxide looks alarming. If output per person in the Third World continues to grow at the same rate as over the past 40 years, the average person in the Third World will be producing 1.7 tonnes of carbon dioxide each year by 2025, more than double the current level of 0.8 tonnes. Meanwhile the number of people would have risen from 3680 million in 1985 to 7114 million. The population increase in the Third World alone would therefore produce an extra 5.75 billion tonnes of carbon dioxide – not too far short of the current world total of 6.8 billion tonnes.
In estimating the growth of the world’s population, the United Nations has made several projections, giving a low, medium and high figure for the year 2025. According to the low projection, world population will reach 6331 million, 783 million less than the medium projection. It is quite possible to achieve this lower figure: it would not require a rapid decline in birth rate of the type seen in China, Thailand or Cuba, but would require the more modest reductions achieved by countries such as Tunisia or Jamaica. Such reductions require a wide choice of freely available family planning methods. Perhaps even more crucial are improvements in mother and child health, female education and women’s status – all valuable measures in their own right.
Achieving the low population projection in developing countries would reduce annual carbon dioxide emissions in 2025 by 1330 million tonnes without reducing carbon dioxide output per person. This compares with some 1570 million tonnes currently produced each year as a result of tropical deforestation.
Slower population growth could make an even bigger contribution in the case of methane, another important greenhouse gas. About half of ‘man-made’ methane emissions come from decomposition in irri gated fields and the guts of livestock. These are not examples of wasteful consumption that could be cut back. The area of irrigated land and the number of livestock have expanded to provide livelihoods for growing rural populations, and to meet the world’s increasing demand for cereals and meat. The irrigated area has grown by about 1.9 per cent a year since 1970, about the same rate as the world’s population. The number of cattle has grown only about half as fast, averaging 0.9 per cent a year.
Livestock and irrigation will both continue to expand in line with populations in developing countries. Slowing the growth of the population is the only feasible strategy for reducing the increase in methane emissions from these sources.
Emissions of greenhouse gas are examples of something added to the environment. Deciding what ‘blame’ is due to population becomes more complicated when the environmental problem involves taking something away. Deforestation, loss of species, loss of soil fertility and erosion all come into this category.
Forests and woodlands in developing countries shrank by 125 million hectares in the 15 years to 1986, according to the UN Food and Agriculture Organization. The anti-Malthusians blame logging and ranching. But ranching has played a minor role outside Latin America. The area given over to pasture in the Third World increased by only 7.9 million hectares over this period – equal to about 6 per cent of the loss of forests. Latin America accounted for the lion’s share of this increase. In Asia the total area of pasture did not increase at all, and in Africa it shrank.
Increase in non-agricultural land, for dwellings, factories, offices, roads and so on, ate up some 58.7 million hectares over this same period – almost 600 square metres per person added to the population. As towns expand mainly in agricultural areas, not in forests or deserts, most of this increase will have been at the expense of agricultural land.
Despite this loss, the total area of farmland grew – by another 58.7 million hec tares. This means that farmland must have expanded, in all, by well over 100 million hectares, half of that simply to compensate for losses to non-agricultural uses. Most of this expansion will have been at the expense of forests and woodland. It probably accounts for more than 80 per cent of deforestation. The rest may be due to degradation through logging or overgrazing.
What share of the blame for the loss of forest to cropland is due to population growth? Between 1971 and 1986 cropland expanded by 0.51 per cent a year. Population grew by 2.2 per cent a year. Food consumption per person grew by 0.58 per cent a year. Technology change, in this case, improved yields so that the area of cropland needed per person decreased, by 2.3 per cent a year. So, of the two factors pushing for an expansion of cropland, population accounts for four-fifths of the effect, the increase in consumption accounts for only one-fifth. On this basis the rough calculation is that population growth was responsible for around two-thirds of deforestation in developing countries.
In recent years, the relative blame may have shifted in certain areas. In Southeast Asia, the pressure to earn foreign currency, and the lure to entrepreneurs of windfall profits from logging, carry much of the blame. Recent massive deforestation in Amazonia is more the result of government policies encouraging land clearance for ranching and farming, as an alternative to land reforms. But within the colonised areas, population growth will create pressures to clear more forest to provide land for the settlers’ children.
The population of developing countries should reach a plateau at around 9.1 billion towards the end of the next century. (It is 4.1 billion today.) The extra 5 billion people will need roughly an extra 280 million hectares of land for non-agricultural needs. This will be taken mainly from prime agricultural areas. Compare this with the total agricultural land of developing countries in 1986 of 675 million hectares. If improvements to agriculture – ‘intensification’ – do not keep pace, the amount of land given over to crops will have to increase to make good this loss, encroaching further on forest and pasture land. Slower population growth can make a sizeable contribution here too.
Soil erosion is a more contentious area. According to anti-Malthusians such as Lappe, inequality and cash cropping on large estates force the rural poor to farm dry, hilly or infertile areas. Because these are more vulnerable to erosion, the total amount of erosion increases. Piers Blaikie, a sociologist at the University of East Anglia, believes that exploitation by national and international elites, rich landowners, large companies and so on, pushes the poor below subsistence level. They are then forced to mine the soil – extracting fertility without restoring it – simply to survive.
Yet in most of West and Central Africa and South Asia it is population growth that fills up existing cultivated areas and forces new families to move out to more marginal areas.
Physically, soil erosion is a function of several factors. The more torrential the rainfall, the greater the erosion. Erosion is also faster if, for example, it has less organic matter to clump soil particles together. Erosion is greater on steeper or longer slopes, and where vegetation cover is thinner.
Population growth affects several of these factors. As human numbers grow, the area of open fields expands. This increases the length of any particular slope. As dense fallow vegetation declines, the overall vegetation cover becomes thinner. Expanding livestock herds help to thin the vegetation by grazing. Because of this, the amount of organic matter in the soil also declines.
This effect of population on erosion assumes that technology does not change. Conservation techniques can reduce the damage: terracing or contour hedging can reduce the length and degree of slope. Adding compost and mulch can increase its organic content. Feeding livestock in stalls can reduce grazing pressure. But there are few places where conservation techniques have kept pace with population growth.
Poverty, exploitation, misguided government policies and so on are significant here. But they affect erosion mainly through the technology factor. Poverty, or low farm prices, for example, would starve farmers of funds, prevent investment and slow technological change. Inequality in land ownership artificially confines the poor to smaller or more marginal areas. Within those areas, higher population densities will lead to greater erosion unless technology keeps pace.
Population growth increases many types of damage to the environment. Slowing that growth reduces the damage. But it may be 20 years before there is any noticeable effect. In the shorter term, other measures will have a greater impact: reducing consumption, shifting to sustainable technologies, halting deforestation, attacking poverty and inequality, introducing land reform.
But in the medium to long term, reducing population growth can have a very significant impact. To achieve this, governments, development agencies and donors of aid must focus their attention on enhancing the rights, education and health of women and children. This will improve both the health of people and the environment. And precisely because it takes so long, action must start right now.
Paul Harrison is the author of Inside the Third World (Penguin, 1987) and helped to research The State of World Population 1990, published by the United Nations Population Fund on 15 May.