Determining the Impact of Human Activity

More people are using more resources with more intensity than at any point in human history. Fresh water, cropland, forests, fisheries and biodiversity all show signs of stress at local, regional and global levels. Increasing pressure on the environment is the result of, on one hand, increasing affluence—that is, more consumption, pollution and waste, and on the other persistent poverty—that is, lack of resources and the technology to use them, and lack of the power to change these circumstances

Growing human numbers play a role in both scenarios. Global use of fuel-wood, for example, has doubled over the past 50 years; the Worldwatch Institute attributes this increase largely to population growth. But the six-fold increase in the use of paper since 1950 is ascribed mainly to rising affluence, and the multiple uses for paper products in an increasingly urban environment.

Population size, growth, distribution and movement help determine the relationship between people and their environments. Similar numbers of people can have very different impacts on the environment, depending on for example social institutions, means of production, property rules and forms of governance. Access to education, health and economic opportunity; consumption levels; and gender differentials (the "quality of human capital") all have an influence.

The most basic determinant of impact is scale. Thirty years ago Paul Ehrlich and J. Holdren described this relationship in the now-famous equation: I = PAT, meaning that people's impact on their environment (I) is a product of population size (P), affluence (A, representing output per capita or the level of consumption) and technology (T, representing the per unit output or efficiency in production).

Poverty and the Environment

Despite soaring global wealth, now estimated at $24 trillion annually, some 1.2 billion people across the world live on less than $1 a day—a condition classified as "extreme poverty" and characterized by hunger, illiteracy, vulnerability, sickness and premature death. Half the world lives on $2 a day or less.

More than a billion people cannot fulfil their basic needs for food, water, sanitation, health care, housing and education. Nearly 60 per cent of the 4.4 billion people living in developing countries lack basic sanitation, almost one third do not have access to clean water supplies, one quarter lack adequate housing, 20 per cent do not have access to modern health services, and 20 per cent of children do not attend school through grade five. Worldwide, 1.1 billion people are malnourished, unable to meet minimum standards for dietary energy; and protein and micronutrient deficiencies are widespread. Nearly 2 billion people in developing countries are anaemic

A breakdown of consumption patterns shows that the "ecological footprint" of the more affluent is far deeper than that of the poor, and in many cases exceeds the regenerative capacity of the earth.

Population growth is not necessarily detrimental to environmental sustainability but it does affect available choices and the prospects of any intervention. Although degradation invariably occurs initially as very low population densities increase, what follows depends on a confluence of factors. If investment needed to improve land is too expensive or the benefits too-long delayed, further degradation will almost certainly result as population rises. In other cases, where a higher population can result in a lower per capita charge for fixed investments (such as water harvesting technology), sustainability and productivity may actually improve in a supportive environment.

If developing countries with rapidly growing populations were encouraged and supported to adopt cleaner technologies, environmental degradation could be mitigated. At current levels of growth, Asia's greenhouse gas emissions are expected to triple in the next 20 years. Effective technology, if it were made affordable, could reduce the growth in emissions.

Source: The State of World Population 2001, Chapter 3: Development Levels and Environmental Impact

United Nations Population Fund (UNFPA).

http://www.unfpa.org/swp/2001/english/index.html