Every person consumes resources and produces waste. The ecological footprint measures how much land and water area a population needs to produce what it consumes and absorb what it discards. It is expressed in global hectares, a standardized unit that accounts for different types of land: cropland, grazing land, forest, fishing grounds, and built-up areas. The concept was developed by Mathis Wackernagel and William Rees in the early 1990s.

Footprints vary enormously. A person in the United States uses roughly eight global hectares. A person in India uses about one. If everyone lived like the average American, humanity would need several Earths to sustain the demand. The global average currently exceeds what the planet can regenerate, which means we are drawing down natural capital. The gap is called ecological overshoot. Carbon emissions from burning fossil fuels make up the largest share of most footprints.

What the footprint includes

• Cropland for food and fiber.
• Grazing land for livestock.
• Forest for timber and carbon absorption.
• Fishing grounds and built-up land.

Critics note that the metric simplifies complex trade-offs. It treats all land as equivalent and does not capture water scarcity or biodiversity loss. Still, it gives a rough picture of how much nature our lifestyles require.