Talk:Global hectare

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There are several revisions of this page referring to the Richmond Tiger football club. I think there is absolutely no relation with the term 'global hectare' and this first paragraph should be entirely removed, or better yet, the article should be reverted to the version of 1 May, before the page was perverted by local football club fans. 94.208.3.57 (talk) 18:13, 31 May 2009 (UTC)

No need to ask. Vandalism should be reverted or corrected without further process. Regards, ... PeterEasthope (talk) 14:41, 6 July 2022 (UTC)

Definition, in original sources

The article needs to present both a simple definition and a full definition. Intro now says,

• One global hectare represents the average productivity of all biologically productive areas (measured in hectares) on earth in a given year.

Productivity normally means "efficiency of production. A productivity measure is expressed as the ratio of output to inputs used in a production process, i.e. output per unit of input." It is not clear how a ratio can be measured in hectares.

The article does not say what biological production is measured: Total biomass? Net increase in biomass after considering deaths? Biomass used for human purposes?

The article cites "Living Planet Report 2004" but the link diverts to Living Planet Report 2016. The 2004 report defines a global hectare as

• a global hectare is a hectare whose biological productivity equals the global average p.10 http://awsassets.panda.org/downloads/lpr_living_planet_report_2004.pdf

The 2016 report says what a global hectare represents:

• global hectare (gha). One gha represents a biologically productive hectare with world-average productivity (Galli, 2015b).
• That citation is: Galli, A. 2015b. On the Rationale and Policy Usefulness of Ecological Footprint Accounting: the case of Morocco. Environmental Science & Policy 48 (21). Doi: 10.1016/j.envsci.2015.01.008., which is at https://www.researchgate.net/publication/271586101_On_the_rationale_and_policy_usefulness_of_Ecological_Footprint_Accounting_The_case_of_Morocco

This Galli 2015 paper also says what a global hectare represents:

• each global hectare (gha) represents the capacity of a hectare of land of world-average productivity (across all croplands, grazing lands, forests and fishing grounds on the planet) to provide ecosystem services useful to people through photosynthesis in a given year (Galli et al., 2007).
• That citation is: Galli, A., Kitzes, J., Wermer, P., Wackernagel, M., Niccolucci, V., Tiezzi, E., 2007. An exploration of the mathematics behind the Ecological Footprint. Int. J. Ecodyn. 2 (4) 250–257. which is at https://www.witpress.com/Secure/elibrary/papers/9781845646547/9781845646547023FU1.pdf

This Galli 2007 paper defines the actual calculation:

• The ecological production of global hectares is calculated by dividing the total ecological production of the Earth by the total biologically productive area available (~11.2 billion hectares). This gives an average productivity per hectare, which is set equal to one global hectare.

Galli's definition of the calculation (production divided by area) shows:

• A global hectare is a measure of sustainable production+waste assimilation, per unit area.
• Area is in the denominator, not the numerator.
• Global hectare is a metaphor, since its units are production+assimilation per unit of area, not actually area. Another metaphor might be "world-wide production per unit of area"
• The world total of global hectares equals the world total of production+waste assimilation.
• Global hectares per person equals production+waste assimilation per person.
• Consumption per person varies and is typically a multiple of production+waste assimilation, such as half, 1, 2, etc.
• Thus consumption per person can be labeled as half, 1, 2, etc. global hectares (meaning it is half, 1, 2, etc. times the "world-wide production per hectare")

The Living Planet 2016 report also addresses the definition of production:

• Conversion from actual land areas to global hectares is performed by means of yield factors and equivalence factors. Yield factors are country-specific and equivalence factors represent a global average, but both values vary by land use and by year (Borucke et al., 2013),
• That citation is Borucke, M., Moore, D., Cranston, G., Gracey, K., Katsunori, I., Larson, J., Lazarus, E., Morales, J.C., Wackernagel, M. and A. Galli. 2013. Accounting for demand and supply of the biosphere’s regenerative capacity: The National Footprint Accounts’ underlying methodology and framework. Ecological Indicators 24: 518-533. Doi: 10.1016/j.ecolind.2012.08.005. which is at https://www.footprintnetwork.org/content/images/article_uploads/NFA_Method_Paper_2011.pdf

This Borucke 2013 paper says that crops, forest, grazing land, and fishery area are added up with weights reflecting the average richness (suitablility) of the land, and assumes the richest lands are used for crops, the least rich are used for grazing, and forests are in the middle. Assimilation of CO2 is assumed to be done by forests. The total production+waste assimilation is this weighted total.

So a global hectare is an average, but is the ratio of the a fraction of the earth's production of

So one global hectare is the average amount of biological production and waste assimilation for humans, per hectare of biologically productive land and fishery (Galli 2007). It measures production and consumption of different products, not land area. It starts with the total biological production and waste assimilation in the world, including crops, forests (such as wood, and CO2 absorption), grazing and fishing (Borucke 2013). The total of these kinds of production, weighted by the richness of the land they use (Borucke 2013), is divided by the number of hectares used (Galli 2007). — Preceding unsigned comment added by Numbersinstitute (talk • contribs) 21:14, 2 March 2018 (UTC)

"... simple definition and a full definition."
I'd rather say an exact definition and a simple description.

Nothing wrong with multiple definitions but clarity of a definition is essential. A nebulous definition can not be a basis for a convincing discussion or conclusion.

Distinction of dimension and unit is lacking throughout the article. "Global hectare" suggests the unit hectare. Mention of ratio suggests a dimensionless number. Therefore a reader is left thinking: what exactly is a global hectare? A quantity which can be expressed in hectares? A dimensionless fraction? What?

More and more words won't help. A clear definition may help.

Regards ... PeterEasthope (talk) 15:20, 6 July 2022 (UTC)