Carbon Footprint

The carbon footprint is a key indicator used to measure the total amount of greenhouse gases emitted into the atmosphere as a result of the activities of individuals, organizations, products, or countries, and to assess the scale of climate change. This measurement is typically expressed in tons of carbon dioxide equivalent (CO₂e). The concept of CO₂e consolidates not only carbon dioxide but also other greenhouse gases such as methane (CH₄), nitrous oxide (N₂O), and fluorinated gases—each with its own global warming potential (GWP)—into a single common scale. This allows the climate impacts of different gases to be compared.

The concept of carbon footprint emerged as one of the subcomponents of the “ecological footprint” approach developed by William E. Rees and Mathis Wackernagel in the 1990s. The term “carbon footprint” was first used in a 1999 BBC publication and gained widespread public recognition through a global advertising campaign launched by BP in 2005. Today, it is recognized as a critical indicator for monitoring, reporting, and reducing environmental impacts by policymakers, businesses, researchers, and individuals.

Sources of Carbon Footprint

The carbon footprint can originate from natural processes and human activities. Greenhouse gas emissions from natural processes—such as volcanic activity, oceanic gas release, decomposition of organic matter, or biological respiration—are largely balanced by natural sinks within ecosystems (forests, oceans, soils). However, emissions resulting from human activities have increased to a degree that disrupts this balance.

The main human-induced emission sources are:

• Energy Consumption: The majority of global greenhouse gas emissions arise from burning fossil fuels—coal, oil, and natural gas—for electricity generation, heating, and industrial processes. The energy sector contributes the highest share to the carbon footprint, both through direct CO₂ emissions and across the entire energy production chain.
• Transportation: Road, air, and maritime transport account for a significant portion of the carbon footprint due to their reliance on fossil fuels. Individual vehicle use, intensive air travel, and long-distance logistics activities increase per capita emissions.
• Industrial Processes: Heavy industries such as cement, iron and steel, and chemicals emit greenhouse gases directly through chemical reactions during production, in addition to energy consumption. For example, CO₂ is released during the calcination of limestone in cement production.
• Agricultural Activities, Deforestation, and Land Use: The agricultural sector is notable for methane emissions from livestock digestion and nitrous oxide emissions from fertilizer use. Deforestation increases atmospheric CO₂ concentrations by reducing carbon sequestration capacity.
• Waste Management: Organic waste decomposing under anaerobic conditions in landfills produces methane gas. The accumulation of waste in disposal sites rather than being recycled is a major factor contributing to the carbon footprint.

Systematic measurement of this indicator provides a fundamental basis for designing emission reduction strategies, formulating climate policies, and developing sustainable production and consumption models.

Types and Classification of Carbon Footprint

The carbon footprint is examined under various categories based on different sources and measurement scopes. This classification helps identify in detail which activities, processes, or production stages give rise to greenhouse gas emissions. Such differentiation enables understanding not only the total volume of emissions but also which sectors and operational steps are responsible.

For instance, direct emissions arise from activities under an organization’s own control, such as fuel consumption in its facilities or vehicles, while indirect emissions stem from the production of purchased electricity, heat, or steam. Broader indirect emissions encompass those generated throughout the supply chain, transportation, waste management, and emissions released during the product’s use phase.

Detailed classifications of this kind enable both organizations and policymakers to develop targeted emission reduction strategies. It also facilitates identifying where efficiency improvements can be made or where alternative technologies can be applied. Thus, comprehensive approaches can be developed for systematically monitoring and reducing the carbon footprint.

Primary and Secondary Footprint

The carbon footprint is analyzed under two main categories: direct and indirect emissions:

• Primary (Direct) Footprint: Includes emissions from activities under the direct control of an individual, organization, or entity. Examples include fossil fuel use for household heating, fuel consumption by company vehicles, or operation of small-scale generators. Carbon emissions resulting from direct energy consumption are among the key indicators in this category.
• Secondary (Indirect) Footprint: Represents greenhouse gas emissions associated indirectly with the entire life cycle of purchased goods and services. Emissions arising from energy use during production, transportation, storage, use, and disposal of products fall within this scope. For example, the energy consumed during the manufacturing of an imported electronic device or the carbon emissions generated from a food product’s journey from farm to table are examples of secondary footprint.

Classification by Scope (GHG Protocol)

The most widely used methodology for corporate carbon footprint calculations is the “Scope” approach defined by the Greenhouse Gas Protocol (GHG Protocol).

• Scope 1: Covers greenhouse gas emissions from sources directly controlled by the organization. Examples include exhaust emissions from company-owned vehicles and emissions from fuel combustion at operational facilities.
• Scope 2: Represents indirect greenhouse gas emissions resulting from the generation of purchased electricity, heating, cooling, or steam. For example, the CO₂ emitted during the production of electricity consumed by an organization falls under this scope.
• Scope 3: Includes all other indirect emissions occurring in the organization’s value chain that it does not directly control but that result from its activities. Examples include production processes in the supply chain, business travel, employee commuting, emissions from product use, and waste disposal.

Other internationally recognized classification and reporting methods, such as the ISO 14064 standard, also exist outside the GHG Protocol.

Calculation Methods

The carbon footprint is calculated primarily by systematically collecting data on activities that cause emissions and multiplying this data by relevant emission factors. Emission factors are coefficients that indicate the amount of greenhouse gas released per unit of a specific activity. For example, the amount of carbon dioxide (CO₂) produced by burning one liter of gasoline is determined through scientific studies using a specific emission factor. This approach enables emissions from different sources to be compared and measured consistently.

At the individual level, carbon footprint calculations typically consider household energy consumption, transportation preferences, types and distances of daily travel modes, dietary habits, and general consumption patterns. Such calculations are mostly carried out using online calculators or mobile applications, helping individuals better understand the environmental impact of their lifestyles.

Corporate carbon footprint calculation is a more comprehensive and multidimensional process. At this stage, Scope 1 (direct emissions), Scope 2 (indirect emissions from purchased energy consumption), and Scope 3 (broader indirect emissions from the supply chain, logistics, waste management, and product life cycles) are analyzed in detail.

The process does not end with data collection; it also includes reporting in accordance with international standards, particularly frameworks such as the Greenhouse Gas Protocol or ISO 14064. Therefore, many organizations hire expert consulting firms or use specialized software to ensure the accuracy of calculations and comply with regulatory expectations. This establishes a reliable data foundation for fulfilling legal obligations and developing long-term sustainability strategies.

Environmental Impacts of Carbon Footprint

An increase in the carbon footprint raises the concentration of greenhouse gases in the atmosphere, altering the Earth’s energy balance. Greenhouse gases (carbon dioxide, methane, nitrous oxide, fluorinated gases, etc.) allow shortwave radiation from the Sun to pass through but trap longwave infrared radiation emitted by the Earth’s surface. This process creates the “greenhouse effect,” which naturally maintains the planet’s temperature at habitable levels. However, the rapid accumulation of greenhouse gases due to human activities has intensified this natural mechanism, leading to a significant rise in global average temperatures compared to pre-industrial levels. Global warming and climate change bring about a series of interconnected and multidimensional environmental impacts:

• Increase in Extreme Weather Events: Energy imbalances in the atmosphere increase the frequency and intensity of storms, hurricanes, floods, excessive rainfall, droughts, and heatwaves. These events strain infrastructure systems, negatively affect agriculture and food production, and cause loss of life and property.
• Rising Sea Levels: Ice sheets in the polar regions and mountain glaciers are melting at an accelerated rate due to rising temperatures. Glacier melt and thermal expansion of seawater raise global sea levels, increasing the risks of flooding, erosion, and saltwater intrusion in coastal areas.
• Loss of Biodiversity: Habitat degradation, ecosystem fragmentation, and changes in temperature and precipitation patterns reduce the living areas of plant and animal species. This leads to species migration, population declines, and extinction of some species.
• Impacts on Food and Water Security: Agricultural production suffers yield losses due to rising temperatures, irregular rainfall, and extreme weather events. Declining water resources pose risks for both drinking water and agricultural irrigation. Marine ecosystems are adversely affected by ocean acidification and rising temperatures, potentially disrupting fisheries and food supply chains.

These impacts affect not only ecological systems but also economic activities, public health, migration patterns, and international security balances. Therefore, reducing the carbon footprint is recognized as one of the core objectives of global climate agreements such as the Kyoto Protocol (1997) and the Paris Climate Agreement (2015).

Methods to Reduce Carbon Footprint

Reducing the carbon footprint requires both individual lifestyle changes and structural transformations at corporate and policy levels. The primary goal is to reduce fossil fuel use and greenhouse gas emissions while increasing energy efficiency, promoting renewable energy use, and improving sustainable resource management.

At the Individual Level

• Transportation Choices: Prioritizing walking, cycling, and public transport for short distances; using electric or hybrid vehicles where possible; reducing air travel.
• Energy Efficiency: Improving home insulation, choosing high-efficiency appliances (Class A or higher), using LED lighting systems, and preventing unnecessary energy consumption.
• Use of Renewable Energy: Installing solar panels at the household level or sourcing electricity from renewable energy providers.
• Dietary Habits: Reducing red meat consumption, preferring locally and seasonally produced foods, and minimizing food waste.
• Consumption and Waste Management: Adopting the “reduce, reuse, recycle” approach, reducing plastic use, and separating waste at the source.

At the Corporate and Policy Level

• Energy Efficiency Programs: Implementing energy management systems in industrial facilities, commercial buildings, and public institutions, and promoting efficient production technologies.
• Investments in Renewable Energy: Encouraging the transition from fossil fuel-based energy production to low-carbon sources such as solar, wind, geothermal, and biomass.
• Sustainable Transportation Infrastructure: Expanding public transit networks, increasing bicycle lanes and pedestrian areas, and supporting electric mobility systems.
• Circular Economy Practices: Adopting production and consumption models that extend product lifespans and encourage repair and reuse.
• Protection of Natural Carbon Sinks: Preserving forests, wetlands, and marine ecosystems; enhancing carbon sequestration capacity through reforestation projects.
• Economic Instruments: Making low-carbon technologies more attractive through carbon taxes, emissions trading systems, and financial incentives.

These measures not only reduce the carbon footprint but also strengthen energy security, enhance economic efficiency, and support the sustainability of ecosystem services.