Biocapacity represents the planet’s capacity to regenerate the natural resources that humans demand and to absorb the waste generated by those activities. It measures the amount of biologically productive land and sea area available to meet human needs. This ecological metric assesses global sustainability by measuring the environment’s ability to support life. The concept provides a framework for understanding whether human economies are operating within the regenerative limits of the biosphere.
Defining Biocapacity and Its Components
Biocapacity is derived from the productivity of several distinct categories of the Earth’s surface that possess the ability to renew biomass through photosynthesis. These biologically productive areas supply the materials and services necessary for human existence.
The largest component is often cropland, which accounts for the area used to produce food, fiber, and biofuels, with its capacity directly influenced by soil fertility and farming technology. Forest land supplies timber and other wood products, and also provides the service of absorbing carbon dioxide emissions. Grazing land is the pasture and rangeland area available to support livestock production, while fishing grounds represent water areas yielding marine and aquatic resources. Built-up land, which includes infrastructure like roads and buildings, is also counted because it permanently displaces the biological productivity of the land it covers. The total of these land types constitutes a region’s or the planet’s total biocapacity.
How Biocapacity is Calculated
To calculate biocapacity and allow for comparison across different land types and countries, a standardized unit of measurement is used: the global hectare (gha). A global hectare is defined as a hectare of biologically productive space with productivity equal to the world’s average for all such areas in a given year. This standardization is necessary because a hectare of highly fertile cropland is inherently more productive than a hectare of marginal grazing land.
The calculation for converting physical area into global hectares involves multiplying the physical area by two primary factors: the yield factor and the equivalence factor. The yield factor accounts for the difference in productivity of a specific land type in a given region compared to the world average for that same land type. For example, a country with highly efficient farming practices will have a higher yield factor for its cropland.
The equivalence factor is a scaling factor that converts different land types into the common unit of the global hectare, reflecting their inherent biological productivity. Cropland, which is very productive, is assigned a higher equivalence factor than forest land or grazing land. By applying both the yield factor and the equivalence factor to the physical area of each land type, researchers arrive at a total biocapacity figure expressed in global hectares.
Biocapacity vs. Ecological Footprint
Biocapacity is best understood when paired with its counterpart, the Ecological Footprint, which measures human demand on the environment. Biocapacity represents the supply side—the regenerative capacity available—while the Ecological Footprint quantifies the demand side required to support consumption and absorb waste. By comparing these two metrics, analysts determine whether a population is living within its ecological means.
When a population’s Ecological Footprint exceeds the available Biocapacity, the world is operating at an ecological deficit. This condition, known as Ecological Overshoot, means that natural resources are being consumed faster than ecosystems can regenerate them. The global community has been in a state of overshoot since the 1970s, depleting its natural capital instead of living off the annual ecological interest.
A biocapacity deficit is not sustainable because it is compensated for by liquidating the planet’s natural assets, such as overfishing, over-harvesting forests, and allowing carbon dioxide to accumulate in the atmosphere. Earth Overshoot Day marks the date when humanity’s demand for the year exceeds the planet’s biocapacity.