Carrying Capacity and the Ecological Footprint

In one line

Carrying capacity asks how many a place can support, and the ecological footprint asks how much land and sea a population's consumption actually requires.

In the wording a student can write in an exam: carrying capacity is the maximum population of a species that an environment can sustain indefinitely, given the resources available and the waste it must absorb. The ecological footprint expresses the demand a population places on the biosphere as the area of biologically productive land and water required to supply what it consumes and to absorb its waste, and compares that area with the biocapacity actually available.

Carrying capacity

In ecology it is the population of a species that a habitat can support without degrading the habitat's ability to support it in future. The definition contains the whole idea: a population above the carrying capacity does not merely go hungry, it reduces the capacity itself.

Applied to human beings it is much harder, for three reasons a candidate should give.

Human beings trade. A city's population is not limited by the resources within the city, because it imports. So the carrying capacity of a place is not determined by that place.

Human beings have technology. Yield per hectare, water use efficiency and energy conversion all change, so the capacity of a given area is not fixed.

Human consumption differs enormously. A hectare supports very different numbers depending on what those people eat, use and waste, so there is no single number even for a single place.

And so it is used comparatively rather than absolutely. The useful question is not "how many can India support" but "is this rate of extraction within what this system can sustain", which is exactly how the Supreme Court used it.

Carrying capacity in Indian law

Facts. Goa Foundation v. Union of India, Writ Petition (Civil) No. 435 of 2012 decided on 21 April 2014, concerned iron ore and manganese mining in Goa carried on after the leases had expired, outside lease areas and without clearances, at a rate unrelated to what the State's ecology could absorb.

Held. The leases had expired on 22 November 2007 and mining after that date was illegal. The Court capped annual extraction pending an expert study of carrying capacity, and directed that ten per cent of the sale proceeds be appropriated to a permanent fund for sustainable development and intergenerational equity.

That is carrying capacity operating as a legal standard. The Court did not decide how much ore Goa could yield; it constituted an expert committee to determine the ceiling and imposed an interim cap. The technique is available wherever extraction is measurable, and it is the fourth of the four techniques in the chapter on environment against development.