1. Introduction

Since the United Nations Conference on Environment and Development in 1992, population growth and increases in consumption in many parts of the world have increased humanity's ecological burden on the planet, even though there has not been an equal corresponding increase in the Earth's bounty of natural resources. As stated in World Wildlife Fund: Living Planet Report 2000, total global consumption of natural resources has risen by fifty percent since 1970, while Earth's natural wealth has decreased by over thirty percent.

At the same time, although global environmental problems are typically considered part of national and international decision-making, it is now much more important to consider the environmental impacts of urban areas, because a rapidly growing proportion of the world's population lives in cities. According to the United Nations Population Division, 2.9 billion people or 47 percent of the earth's population lived in urban areas in 2000. In 2007, it is projected that the global urbanization rate will reach 50 percent, and in 2030 it should reach 60 percent. In other words, the world's population could increase by 2.2 billion people in 2030, with 2.1 billion of these people living in cities. Nearly all of this additional population growth is expected to occur in developing nations, and practically all of it will be concentrated in urban areas.

As a response to this, municipal decision-makers must be able to measure urban and regional ecological impacts to inform environmental policy at the local level. One way to do this is through ecological footprint analysis, which was invented in 1992 by Dr. William Rees and Mathis Wackernagel at the University of British Columbia. As an introductory report, this guide focuses on the applicability of EF analysis for cities and regions, and does not explain footprint calculation methodologies in detail.

2. What is an Ecological Footprint?

All of the resources which people use for their daily needs and activities come from somewhere, even if not from their immediate surroundings. Food, electricity, and other basic amenities for survival must be produced within the confines of nature, using raw natural resources. Based on this relationship between humanity and the biosphere, an ecological footprint is a measurement of the land area required to sustain a population of any size. Under prevailing technology, it measures the amount of arable land and aquatic resources that must be used to continuously sustain a population, based on its consumption levels at a given point in time. To the fullest extent possible, this measurement incorporates water and energy use, uses of land for infrastructure and different forms of agriculture, forests, and all other forms of energy and material "inputs" that people require in their day-to-day lives. It also accounts for the land area required for waste assimilation.

3. Scales of Measurement

Footprints can be measured at an individual level, or for cities, regions, countries, or the entire planet. Through specialized adjustments, EF analysis can also be used for specific activities, or to measure the ecological requirements of producing specific goods or services.

Analysts examine the quantity and different types of natural and manufactured materials and services used, and then use a variety of calculations to convert this into a land area. Footprints indicate how much "nature" is available for a defined population to use, compared to how much it needs to maintain its current activities. Obviously, the size of a footprint will vary depending on the volume and different types of natural resources consumed by a population, which will in turn depend on lifestyle choices, income levels, and technology. Therefore, footprints provide compelling evidence of the impacts of consumption.