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The global hectare (gha) is a measurement unit for the
ecological footprint The ecological footprint is a method promoted by the Global Footprint Network to measure human demand on natural capital, i.e. the quantity of nature it takes to support people or an economy. It tracks this demand through an ecological accounti ...
of people or activities and the
biocapacity The biocapacity or biological capacity of an ecosystem is an estimate of its production of certain biological materials such as natural resources, and its absorption and filtering of other materials such as carbon dioxide from the atmosphere. B ...
of the
Earth Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's sur ...
or its regions. One global hectare is the world's annual amount of biological production for human use and human waste assimilation, per hectare of biologically productive land and fisheries. It measures production and consumption of different products. It starts with the total biological production and waste assimilation in the world, including crops, forests (both wood production and CO2 absorption), grazing and fishing. The total of these kinds of production, weighted by the richness of the land they use, is divided by the number of hectares used. Biologically productive areas include cropland, forest and fishing grounds, and do not include deserts, glaciers and the open ocean. "Global hectares per person" refers to the amount of production and waste assimilation per person on the planet. In 2012 there were approximately 12.2 billion global hectares of production and waste assimilation, averaging 1.7 global hectares per person. Consumption totaled 20.1 billion global hectares or 2.8 global hectares per person, meaning about 65% more was consumed than produced. This is possible because there are natural reserves all around the globe that function as backup food, material and energy supplies, although only for a relatively short period of time. Due to rapid population growth, these reserves are being depleted at an ever increasing tempo. See
Earth Overshoot Day Earth Overshoot Day (EOD) is the calculated illustrative calendar date on which humanity's resource consumption for the year exceeds Earth’s capacity to regenerate those resources that year. The term " overshoot" represents the level by which ...
. The term "global hectar" was introduced in the early 2000s, based on a similar concept from the 1970s named "ghost acerage".Mathis Wackernagel, William Rees, ''Our Ecological Footprint: Reducing Human Impact on the Earth'' (1998), p. 49. Opponents and defenders of the concept have discussed its strengths and weaknesses.


Applications

The global hectare is a useful measure of biocapacity as it can convert things like human dietary requirements into common units, which can show how many
people A person ( : people) is a being that has certain capacities or attributes such as reason, morality, consciousness or self-consciousness, and being a part of a culturally established form of social relations such as kinship, ownership of prope ...
a certain region on earth can sustain, assuming current
technologies Technology is the application of knowledge to reach practical goals in a specifiable and reproducible way. The word ''technology'' may also mean the product of such an endeavor. The use of technology is widely prevalent in medicine, science, ...
and
agricultural Agriculture or farming is the practice of cultivating plants and livestock. Agriculture was the key development in the rise of sedentary human civilization, whereby farming of domesticated species created food surpluses that enabled peopl ...
methods. It can be used as a way of determining the relative carrying capacity of the earth. Different hectares of land can provide different amounts of global hectares. For example, a hectare of lush area with high
rainfall Rain is water droplets that have condensed from atmospheric water vapor and then fall under gravity. Rain is a major component of the water cycle and is responsible for depositing most of the fresh water on the Earth. It provides water f ...
would scale higher in global hectares than would a hectare of desert. It can also be used to show that consuming different foods may increase the earth's ability to support larger populations. To illustrate, producing meat generally requires more land and energy than what producing vegetables requires; sustaining a meat-based diet would require a less populated planet.


Hectare equivalents

On average, a global hectare can be produced in the area of a standard hectare. A
hectare The hectare (; SI symbol: ha) is a non-SI metric unit of area equal to a square with 100- metre sides (1 hm2), or 10,000 m2, and is primarily used in the measurement of land. There are 100 hectares in one square kilometre. An acre i ...
(; symbol ha) is a unit of area equal to (a square 100 metres on each side or 328 feet on each side), 2.471 acres, 0.01 square kilometers, 0.00386102 square miles, or one square
hectometre The hectometre ( International spelling as used by the International Bureau of Weights and Measures; SI symbol: hm) or hectometer (American spelling) is a unit of length in the International System of Units (SI), equal to one hundred metres and t ...
(100 metres squared).


See also


References

Ecology {{ecology-stub