Definition and scope of carbon footprint
The carbon footprint is an indicator that compares the amount of greenhouse gases that an activity, product, company or country adds to the atmosphere.
To calculate it, the emissions of the entire life cycle, from production and supply chain to use and disposal, are added up.
It is generally expressed in tons of carbon dioxide equivalent (tCO₂-eq) per comparative unit, such as per year, per kilogram of protein or per kilometer traveled.
Methodologies such as the Greenhouse Gas Protocol, ISO standards, PAS and others include both direct emissions (scope 1) and indirect emissions (scopes 2 and 3).
For products and food, the carbon footprint comprises all stages of the chain, from land use change and agricultural production to processing, transportation, packaging and losses.
The impact varies greatly depending on the food: producing 100 g of protein from peas emits about 0.4 kg of CO₂-eq, while obtaining the same amount of protein from beef generates approximately 35 kg of CO₂-eq, almost ninety times more.
In transportation there are also significant differences: walking or cycling one kilometer produces between 16 and 50 g CO₂-eq, and train trips are generally more emissions efficient than private vehicle trips for medium to long distances.
Direct emissions (Scope 1) come from sources controlled by the organization or the individual, such as private vehicles or gas boilers.
Scope 2 indirect emissions are associated with the purchase of electricity, heat or steam.
While Scope 3 covers activities in the value chain, such as raw material transportation, product consumption and waste treatment. Understanding these scopes helps to identify the phases with the greatest impact and to devise reduction strategies.
On a global scale, the carbon footprint is used to compare countries: in 2014 the world average was about 5 tCO₂ per person, the EU average in 2007 exceeded 13 t and countries such as the United States, Luxembourg or Australia exceeded 25 tCO₂e per person.
Analyses indicate that, to stay within the target of limiting warming to 2 °C, the per capita footprint would have to be reduced to about 2-2.5 tCO₂e by 2050.
The GHG: Green House Gas Protocol / Protocolo de Gases de efecto Invernadero.
Among all the ways of measuring the carbon footprint, the Greenhouse Gas Protocol's Policy and Action Standard (public and free of charge) stands out, which expands on this vision.
Defines GHG assessment as the estimation of changes in greenhouse gas emissions or removals resulting from a policy or action.
Emissions are the releases of these gases into the atmosphere, while removals are the removals or capture of GHGs by sinks such as vegetation.
The standard specifies that not only carbon dioxide but also methane (CH₄), nitrous oxide (N₂O), hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), sulfur hexafluoride (SF₆) and nitrogen trifluoride (NF₃) should be considered.
These seven gases are listed in the UN Framework Convention and the Kyoto Protocol; the standard states that other gases recognized by the IPCC or the Montreal Protocol may be added.
The document recommends clearly defining sources (activities or processes that emit GHGs) and sinks (processes that remove GHGs) and developing a causal diagram showing how a policy or action leads to changes in emissions.
This approach helps to identify direct and indirect effects, within and outside the jurisdiction where the policy is implemented, and to distinguish between intended and unintended effects.
To quantify the effect of a policy, the standard requires that a reference scenario (without the policy) and a scenario with the policy be established, and that the difference between the two represent the net change in emissions.
In this way, emission reductions (or increases) can be attributed to a specific action and different interventions can be compared more rigorously.
In summary, the carbon footprint is a useful tool for measuring and comparing the climate impact of organizations, products, activities and policies.
Incorporating the guidelines of the Policy and Action Standard helps to consider all relevant greenhouse gases and to analyze the causes and effects of mitigation measures in greater detail.
ISO standards and their contribution to carbon footprint management (non-exhaustive)
On the other hand, the ISO standards expand the previous definition of carbon footprint with the contribution of the ISO 14064-1, 14064-2 and 14064-3 standards.
These standards are part of the ISO 14000 family and are designed to provide a harmonized framework for quantifying and verifying emissions, thus complementing the Greenhouse Gas Protocol (GHG Protocol):
The ISO 14064 series - developed by the International Organization for Standardization (ISO) - helps organizations to transparently measure, manage and report their greenhouse gas emissions and removals. It consists of three parts:
- ISO 14064-1 specifies the principles and requirements for the quantification and reporting of greenhouse gas emissions and removals at the organizational level. This standard guides companies in developing their GHG inventory and introduces principles such as relevance, completeness, consistency, accuracy and transparency. It defines how to establish the boundaries of the inventory - for example, which facilities are part of the organization - and distinguishes between organizational boundaries (identifying facilities under financial or operational control or according to shareholding) and operational boundaries (which activities are included). It also requires identifying the sources and sinks of GHGs under the organization's control and classifying emissions into direct (resulting from own activities, such as fuel combustion) and indirect (associated, for example, with purchased electricity or other processes outside direct control). For each source, data should be collected, emission factors applied and emissions consolidated so that the inventory can be audited.
- ISO 14064-2 establishes requirements for quantifying, monitoring and reporting emission reductions or carbon removal improvements at the project level. It is oriented to specific programs - such as energy efficiency or carbon sequestration projects - and provides a methodology for defining a reference scenario and calculating the reductions achieved against that scenario.
- ISO 14064-3 provides guidelines for validating and verifying emission declarations and reductions or removals achieved at either the organizational or project level. This standard sets out the principles that verification processes must comply with, including impartiality, ethical behavior, fair presentation and professional diligence, in order to ensure the credibility of GHG reports.
Overall, ISO 14064 offers a complementary regulatory framework to carbon footprinting: at the organizational level, it provides clear criteria to delimit the calculation scopes and ensure that all relevant sources and sinks are included in the inventory; at the project level, it facilitates the rigorous measurement of emission reductions; and through its third party ensures that reported data can be verified by third parties.
These standards, like the GHG Protocol, promote consistency, transparency and comparability of results, enhancing the credibility of carbon footprint claims.
Sources : Wikipedia. GHG Protocol, ISO Standards.
