IB Geography 3.1.2 Measuring Trends in Resource Consumption Notes

The Ecological Footprint Reports Area in Global Hectares of World-Average Productivity

Every consumption metric must define which resources it counts, whose consumption it attributes them to and which unit it reports.

1. A global hectare is a standardized unit representing one hectare with world-average biological productivity.
   1. It allows different types of productive land and water to be converted into a common unit for comparison.
2. Yield Factor
   1. This compares one country's land of a given type against the world average for that type, in world-average hectares per national hectare.
3. Equivalence Factor
   1. This converts a world-average hectare of one land type into global hectares, which gives cropland a larger factor than grazing land because cropland is more productive.
4. The accounts add six components: cropland, grazing land, fishing grounds, forest products, built-up land and carbon.
   1. Five of those are areas that supply something, such as the cropland behind a diet or the forest behind sawn timber.
   2. The sixth, the carbon footprint, is the forest area that would be needed to sequester the carbon dioxide from burning fossil fuels, so it is a disposal area rather than a supply area.

Biocapacity Is the Supply Side, and Its Difference from the Footprint Is a Deficit or a Reserve

1. Biocapacity is the capacity of a defined area's ecosystems to regenerate what people demand from them, measured in the same global hectares.
2. Global Footprint Network puts world biocapacity at 1.5 global hectares per person for 2025, from 12.2 billion hectares of biologically productive surface shared between 8.2 billion people.
3. Biocapacity minus footprint for the same population gives an ecological reserve where the answer is positive and an ecological deficit where it is negative, so a country with a large footprint still holds a reserve if its biocapacity per person is larger.
4. Canada, Brazil, Sweden and Gabon are among the countries Global Footprint Network's 2026 deficit-day page lists with no deficit day, because their biocapacity exceeds their footprint.

The World Footprint Divided by World Biocapacity Gives 1.73 Earths for 2026

1. Global Footprint Network's June 2026 release puts human demand 73 percent above what ecosystems regenerate and states this as 1.73 Earths, a unitless ratio of the world footprint to world biocapacity.
   1. The release calls it the highest level of global overshoot in human history, a ranking that holds inside the 2026 edition because each edition revises the whole series.
2. Global Footprint Network's 2026 country calculations put world biocapacity at 1.48 global hectares per person for the 2024 data year, the same measure as the 1.5 above at a different data year and rounding.

How Earth Overshoot Day Is Derived From the Same Accounts

1. Global Footprint Network computes Earth Overshoot Day as Earth's biocapacity divided by humanity's Ecological Footprint multiplied by 365, which writes that same ratio onto a calendar and moves the date whenever the accounts are revised.
2. Earth Overshoot Day 2026 fell on 30 July, six days later than the 24 July date published for 2025.
   1. Global Footprint Network attributes eight of those days to data revisions, chiefly an upward revision of the ocean's capacity to absorb carbon, and two days in the opposite direction to real growth in overshoot.

Two National Comparisons Exist, and They Put Ethiopia and the United States Days Apart

1. Country Overshoot Day
   1. This is the date Earth Overshoot Day would fall if everyone consumed like the residents of one country, computed as 365 multiplied by world biocapacity per person divided by that country's footprint per person.
   2. Global Footprint Network works the 2026 Swiss case as 365 times 1.48 divided by 4.15 global hectares per person for 2024, giving 11 May.
   3. On the same 2026 figures the number of Earths implied by living like one country's residents is 10 for Qatar, 5.1 for the United States, 4.7 for Denmark, 2.5 for China and 1.3 for Indonesia, all on 2024 data, while India at 75 percent of one Earth and Ethiopia at 60 percent sit below 1.48 global hectares per person and so have no country overshoot day at all.
2. Country Deficit Day
   1. This is the date a country's residents have used as much as that country's own ecosystems regenerate in a year, so the denominator is domestic biocapacity rather than the world average.

Why a Low Footprint Is Not Evidence of Living Within Limits

1. Ethiopia's 2026 country deficit day is 10 July.
2. The United States reaches its own on 2 July, eight days earlier.
3. Ethiopia reaches a deficit on a footprint below the world average because its own biocapacity per person is small.
4. India's 2026 deficit day is 17 April, so its ecosystems regenerate about 29 percent of what its residents consume.
5. The United Kingdom's falls on 19 April and Japan's on 26 February.

A National Footprint Splits into Production and Consumption the Way an Emissions Account Does

1. The accounts compute a country's consumption footprint as production plus imports minus exports, written EFC = EFP + EFI - EFE in the 2019 Working Guidebook.
2. Consumption-based greenhouse-gas accounting uses the same reassignment by subtracting emissions embodied in exports and adding those embodied in imports.
3. Carbon leakage occurs when territorial emissions fall because production moves abroad; the resource equivalent shifts cropland, water and ore into the producing territory without lowering demand in the consuming country.
4. Higher income raises the volume of goods bought, the floor area heated and the distance travelled, each of which converts into global hectares through the land and energy behind it.
   1. Trade then decides which country those hectares are booked against, so part of the relationship between income and footprint is an artefact of where production sits.

Personal Calculators Model an Individual from a Questionnaire and National Averages

1. Global Footprint Network's calculator at footprintcalculator.org asks about diet, housing, transport and consumption of goods.
2. It returns a footprint in global hectares, a personal overshoot day and the number of planets that would be needed if everyone lived that way.
3. A questionnaire cannot measure one person's share of shared infrastructure, so the calculator assigns national average values for roads, hospitals, schools and public services.
4. Collins and others (2020), in Environmental Research Letters, surveyed 4,245 calculator users, 2.2 percent of the 192,300 registered, of whom 62 percent had used the calculator within an educational context.
5. Those users returned a mean footprint of 4.6 global hectares per person, which the authors set against the world average biocapacity of 1.68 global hectares per person.
   1. Dividing 4.6 by that 1.68 puts the mean user at 2.7 Earths, which places a personal overshoot day on 13 May.
6. Only 23 percent of those users said the calculator gave them the information they needed to reduce their own footprint, though 91 percent found it valuable for generating knowledge.

The Water Footprint Measures Volume and Separates Green, Blue and Grey Water

1. Hoekstra and Mekonnen (2012), in the Proceedings of the National Academy of Sciences, put the global water footprint at 9,087 billion cubic metres a year averaged over 1996 to 2005, with agricultural production contributing 92 percent.
2. The green water footprint is consumptive use of rainwater held in the soil, which that study puts at 74 percent of the global total.
3. The blue water footprint is consumptive use of surface water and groundwater, at 11 percent of the total, which is the part irrigation and industry draw from rivers and aquifers.
4. The grey water footprint is the volume of freshwater needed to dilute pollution back to water quality standards, at 15 percent of the total.
5. Water embedded in traded goods is what Tony Allan named virtual water in 1993, credited in the Stockholm International Water Institute's citation for his 2008 Stockholm Water Prize.
6. The same study gives the average consumer in the United States 2,842 cubic metres a year, against 1,071 in China and 1,089 in India.
   1. Hoekstra and Chapagain (2006) attribute a national water footprint to consumption volume, consumption pattern, climate and agricultural water use efficiency, so income alone does not order the ranking.

Material Footprint and Domestic Material Consumption Weigh Mass and Disagree About Imports

1. Domestic Material Consumption
   1. The United Nations metadata for SDG indicators 8.4.2 and 12.2.2 defines it as domestic extraction plus physical imports minus physical exports, counting traded goods at the weight they cross the border.
2. Material Footprint
   1. SDG indicators 8.4.1 and 12.2.1 instead count raw material extracted anywhere in the world to meet a country's final demand, so imported laptops carry the ore and waste rock behind them.
3. The International Resource Panel's Global Resources Outlook 2024 records global material extraction rising from 30 billion tonnes in 1970 to 106 billion tonnes in 2020, and average material use rising from 23 to 39 kilograms per person per day.
4. The same report puts material use in low-income countries at about one sixth of the high-income level and the associated climate impacts at about one tenth.

Relative Decoupling Lowers Intensity While Absolute Decoupling Lowers the Total

1. Resource intensity is resource use divided by output, so a falling intensity is compatible with a rising total.
2. Relative decoupling means resource use or emissions grow more slowly than GDP, which lowers the intensity while the total still rises.
3. Absolute decoupling means resource use or emissions fall while GDP grows, which lowers the total itself.
4. Haberl and others (2020), in Environmental Research Letters, reviewed 835 peer-reviewed studies and found relative decoupling frequent for material use and for carbon dioxide and greenhouse gas emissions.
5. They found sustained absolute decoupling scarce, and concluded that large rapid absolute reductions cannot be achieved at observed decoupling rates.

The Footprint's Criticisms Concentrate on the Carbon Component and on Aggregation

1. Blomqvist and others (2013), in PLOS Biology, removed the carbon component and found global biocapacity about 45 percent above the footprint for 2008, concluding that virtually all of the ecological overshoot comes from carbon dioxide reframed as a hypothetical forest area.
2. Rees and Wackernagel (2013), replying in the same journal, put carbon at 55 percent of the total footprint in 2008 and at 7 percent of Tanzania's domestic footprint.
   1. The two percentages answer different questions, one a biocapacity surplus with carbon removed and the other carbon's share of the footprint, so neither refutes the other.
   2. Blomqvist and others answered again in the same issue, which closed the exchange unresolved.
3. The 2008 edition of the accounts dropped nuclear electricity, which had stood at about 4 percent of humanity's footprint in 2003, because Global Footprint Network found no scientific basis for treating its demands as equal to the carbon footprint of fossil-fuel electricity.

What the Accounts Leave Outside the Ledger

1. Global Footprint Network's FAQ states that freshwater is cycled through the biosphere rather than produced by biologically productive area, so water scarcity does not enter the footprint.
2. The same FAQ states that the Ecological Footprint is not an indicator of the state of biodiversity, and that minerals mined from below the biosphere carry no yield value.
3. Summing six unlike components into one total leaves the headline figure unable to say which pressure moved.

Ratios, Choropleths and Correlation Require the Right Inputs

1. Ecological footprint is an index and ratio, like the Gini coefficient, Human Development Index and dependency ratio.
2. Percentages and ratios turn one figure into another, so dividing a national footprint per person by 1.48 global hectares returns the number of Earths, as 4.15 divided by 1.48 does for Switzerland.
3. Choropleth maps carry a variable by area shading, so reading one for value requires a legend giving the class intervals, the variable and the data year.
4. A valid Spearman rank correlation requires two paired rankings; the country examples provide neither an income series nor enough footprint values.