IUCN - The World Conversation Union

The number of people on Earth, where they live, and how they live all affect the demands and pressures placed on the environment. However, the links between demographic change and the environment are more complicated than people once thought. Human population dynamics lead to environmental change and are in turn affected by it. Consumption patterns, development choices, wealth distribution, government policies and technology can mediate or exacerbate the effects of demographic change on the environment. The precise impact of a given change depends on the interplay among all these factors.

Human population dynamics include phenomena such as population size and rate of change, migration, age structure, household size and gender balance. At a very basic level, the size of the human population determines the total demand for food, water, shelter and other goods and services, which in turn require environmental inputs. Other demographic factors affect the composition of goods and services required, for example, the balance between education and health care in societies with a large proportion of children or elderly people. This in turn affects the structure of the economy and likewise the demands placed on the environment.

World population continues to increase, with the most rapid growth forecast to occur in developing countries. According to estimates by the United Nations, the population of developing regions is projected to increase from about 4.9 billion in 2000 to 8.1 billion by 2050, while that of industrialized regions, currently 1.2 billion, is expected to change little over the next 50 years. Areas experiencing rapid population growth are also those where the majority of the earth’s remaining biodiversity can be found. However, biodiversity conservation is generally considered a low priority compared with meeting the needs of a rapidly growing population for jobs, food, housing, health and education. This in turn reflects widespread misunderstanding of the important role of healthy ecosystems in sustaining a growing population.

Continuing population growth is difficult to reconcile with any practical vision of sustainable development. Among other changes, the shift to sustainability requires a demographic transition leading to stabilization of human population. Fortunately, we are seeing this trend taking place steadily around the world. The fertility rate has dramatically fallen in most countries, and globally it is now at half the rate of the 1960s. It is expected to drop below replacement level in the next few decades – a goal that has been already met in more than one-third of the countries of the world. Given the complexity of demographic phenomena, effective action on population issues from a sustainability perspective requires a sophisticated understanding of how changes in the size, composition and location of human populations affect the use of natural resources and environmental quality.

IUCN has expressed its concern on population and environment through a number of Resolutions. For instance, Resolution GA 15.03 of 1981 on “People, resources and environment” called for governments to develop strategies that inter-relate population control, production and consumption policies and sustainable use to conservation of the environment.

SPP has produced a series of practical, action-oriented tools for integrating population and natural resource dynamics in national and local planning processes. See Our People, Our Resources: Supporting Rural Communities in Participatory Action Research on Population Dynamics.

Read an article of IUCN's OMS office for Southeast Asia (SEARO) on the relationship among women, men and the environment, and the environmental impact of their different social roles.