Footprints and Handprints

Footprint figures are quoted constantly and almost never together with the accounting choice that produced them. The paper starts from that gap and works down from countries to individuals to single products, then looks at the ecological footprint and at the handprint, a newer concept that counts what someone changes at other people.

One country, four correct numbers

Ask how large Germany’s carbon footprint is per person and the published answers run from 6.8 to 10.4 tonnes a year. None of them is wrong. They differ in what they count: emissions inside the border only, or also the emissions caused abroad by goods bought in Germany; carbon dioxide only, or all greenhouse gases; and whether each resident is charged an equal share of roads, hospitals and public administration. The narrowest figure, territorial CO₂ only, is the one national climate law is written against. The widest, 10.4 tonnes, is what the German environment agency’s consumer calculator shows (UBA CO₂ calculator background report). Correcting for trade alone moves Germany’s figure from about 7 to about 9 tonnes of CO₂, so roughly three of every ten tonnes a German resident is responsible for are released outside Germany (Our World in Data, consumption-based CO₂).

A national total divided by the population is also a share, not a personal footprint. It hands everyone the same value, while in Germany the lowest-emitting tenth of the population sits near 7 tonnes and the highest near 17.7. Worldwide the spread between income groups is now larger than the spread between countries, and for the richest percentile most emissions come from what they own and invest in rather than from what they consume. A calculator that asks about flights, heating and diet therefore understates exactly the group with the largest footprint.

What sits inside a personal footprint

The consumer calculator is built in two ways at once. Whatever a person can report about themselves, kilometres driven, heating oil, electricity, flights, is calculated bottom-up with emission factors. Everything nobody can report, the emissions behind a shirt, a restaurant meal or a hospital, comes top-down from national sector totals divided by the population and scaled by the person’s answers. Nobody adds up the individual products they bought.

The categories are not where intuition puts them. The largest is general consumption, everything else bought together with the machines and factory buildings that made it. Household electricity is only about half a tonne, which is why a green tariff moves a personal total less than expected. And 1.2 tonnes are an equal share of public infrastructure that no personal decision can change.

How a product footprint is calculated

Two methods produce product footprints, and knowing which one was used explains most disagreements between published figures. Tracing a supply chain step by step is precise about what it includes but has to stop somewhere, usually before the factory building and the machines; that cut-off understates the total by 20 to 50 %, always in the same direction. Working from national input-output tables instead misses nothing, because every purchase between industries is recorded somewhere, but it treats everything within one industry as identical. Whether “the factory” is in a footprint therefore depends on the method: in the whole-economy method used by the German calculator it is counted, but spread across the whole shopping basket rather than attached to the product bought.

Green electricity is a boundary question of the same kind. Company reporting rules allow a contract-based electricity figure close to zero next to the grid-average one, without requiring that the purchase added any new renewable generation (GHG Protocol, Scope 2 guidance).

The ecological footprint is mostly carbon

The ecological footprint measures an area, the biologically productive land and sea a population needs, in global hectares. Its carbon component converts emissions into the forest area that would be needed to absorb them, a forest that does not exist. That component dominates: for Germany in 2023 it was 2.43 of 4.03 global hectares per person, about 60 % (Global Footprint Network data). Without it, what remains is close to what Germany’s own land and sea regenerate and has barely moved since 1961. The well-known “1.7 Earths” is therefore essentially a statement that humanity emits more CO₂ than forests absorb, which is true and already measurable in tonnes. Critics have argued for years that this makes the metric unsuitable for decisions (Blomqvist et al. 2013); its authors reply that it answers a different question (Rees and Wackernagel 2013). Both are right about different things: the area framing and Earth Overshoot Day communicate overshoot well, but for choosing between two options the conversion to area adds an assumption and no information. Overshoot Day is also recalculated every year, and in 2026 a revised ocean-uptake figure moved the date more than the real change did.

What one person can change

Reviews of individual climate actions rank living without a car, avoiding long flights, renewable electricity and a plant-based diet as the largest private levers (Ivanova et al. 2020, Wynes and Nicholas 2017). Those are medians for an average-emitting population. A saving is capped by what someone already emits in that category, so living car-free is worth nothing to someone without a car, and the switch to green electricity is worth at most the half tonne a German household uses. For a German resident, giving up animal products for a year is worth roughly one and a half to two return flights of about 1000 km. Taken together, the realistic private levers remove about five to seven of the 10.4 tonnes. The German environment agency puts a compatible level well below one tonne per person and year (UBA). What remains is the electricity grid, buildings, railways, freight and industrial heat, none of which is a consumption decision.

The handprint

The handprint counts what someone changes at other people: a landlord persuaded to insulate a building, an employer who puts solar on the roof, a council that changes a bus route. A personal footprint cannot show any of this. The concept was developed in Germany by Germanwatch with Brot für die Welt (Germanwatch). Unlike a footprint, it is deliberately not exclusive: when a tenant gets a block of ten flats insulated and five tonnes a year are avoided, the residents’ footprints fall by five tonnes in total, and the tenant can honestly claim the same five tonnes as a handprint. Adding both gives ten tonnes from an event that saved five. That is not an error, because the two numbers answer different questions, but it is why a handprint may be reported beside a footprint and never subtracted from it. Claims that slide between the two, “our product saved four million tonnes” against “we cut our emissions by four million tonnes”, are the standard shape of greenwashing.

What follows

Before comparing any two footprint figures, three properties have to be fixed: which gases, which boundary, and whether trade is counted. Where a decision depends on the answer, tonnes of CO₂e with a stated boundary is the defensible unit; the ecological footprint is useful to make overshoot visible and not to rank options. A personal footprint is worth computing once, to find the two or three levers that are actually large and to see the floor underneath them that only structural change can reach, which is where the handprint comes in.

The full paper, with all figures, the data behind them and every source, is the PDF on this page.