Navigating sustainability: a comprehensive guide to key terms
Published in 2025
Net-zero, carbon emissions, carbon-neutral – we hear these sustainability related terms everywhere: in politics, business, and daily life. Sustainability is critical to our global efforts to combat climate change, ensuring a healthy planet for future generations. Understanding sustainability terms and their distinctions is crucial to navigate this complex field. This knowledge helps us separate genuine impact from greenwashing, and fosters trust and meaningful change.
This blog article compiles key sustainability terms that are encountered daily, providing clarity.
Climate change
The term climate change refers to long-term alterations in temperature and weather patterns. These changes can occur naturally, however, the continuous increase in global warming since the 19th century is attributable to human activities. The burning of fossil fuels, deforestation, and industrial processes release greenhouse gases into the atmosphere. The high concentration of greenhouse gases is causing the Earth to heat up more and more, causing global warming. Today, the consequences of climate change include intense droughts, water scarcity, severe wildfires, rising sea levels, floods, melting polar ice, catastrophic storms, and biodiversity loss.1
Carbon emissions
Carbon dioxide (CO2) is a natural byproduct of cellular respiration in many living organisms. However, it is also produced during the combustion of coal, wood, and oil. Thus, carbon dioxide stems from a variety of sources, including transportation, energy production, agriculture, and industrial processes, making it a major driver of climate change.2 As a greenhouse gas, CO2 traps heat in the Earth’s atmosphere, maintaining temperatures suitable for life. However, excessive CO2 concentrations strengthen the greenhouse effect, accelerating global warming.3
According to the International Energy Agency, global energy-related CO2 emissions reached a new high of more than 37.4 billion tons in 2023.4
There are different ways to reduce carbon emissions: reducing activities that produce CO2, capturing and storing CO2 underground, or repurposing this ‘waste product’ into a valuable resource, such as a feedstock for renewable fuels.5
Carbon footprint
The carbon footprint is the amount of greenhouse gases, particularly carbon dioxide, that an individual, organization, product, activity, or process is directly or indirectly responsible for emitting into the atmosphere.6 It measures greenhouse gases caused by human activity, shows its impact on the environment, and is a central component of life cycle assessment or sustainability reporting. The Greenhouse Gas Protocol, a widely accepted standard, categorizes emissions into three different scopes: Scope 1, Scope 2, and Scope 3. Read more here.
Online carbon footprint calculators can help individuals and businesses estimate their impact.
Decarbonization and defossilization
Decarbonization and defossilization are two related but distinct concepts aimed at reducing the environmental impact of human activities, particularly in the context of addressing climate change.
Decarbonization refers to the process of reducing or eliminating CO2 emissions, specifically from various sectors of the economy, such as energy production, transportation, and industry. It involves shifting from carbon-intensive processes that include fossil fuels, coal, oil, or natural gas, to low-carbon or carbon-free alternatives.7 For example, shifting from vehicles with internal combustion engines to electric vehicles is a decarbonization strategy.
Defossilization is a more specific term that focuses on reducing reliance on and use of fossil fuels, which are carbon-rich energy sources derived from ancient organic materials, such as coal, oil, and natural gas. Thus, it involves the transition from fossil fuels to alternative renewable energy sources, such as wind, solar, and hydropower. In aviation, defossilization includes switching from fossil-based kerosene to sustainable aviation fuels that close the carbon cycle by emitting only as much CO2 as was used to produce them.
Carbon-neutral
The term carbon-neutral applies specifically to CO2 emissions. Carbon neutrality indicates that the carbon dioxide output has a net neutral impact on the environment, preventing further contributions to global warming.8 Technologies are considered carbon-neutral if they do not release any new CO2 into the atmosphere. Carbon neutrality can be achieved through emission reductions or offsetting strategies such as carbon capture and reforestation. Many companies and countries are setting carbon-neutral targets as part of broader climate commitments, often using carbon credits to balance unavoidable emissions. However, achieving true carbon neutrality requires careful verification to ensure that offsets are credible and lead to real, measurable emission reductions.
Climate-neutral
Climate neutrality encompasses all greenhouse gases, including CO2, methane, nitrous oxide, and industrial gases. Organizations, products, services, or individuals are only climate-neutral if they are not only greenhouse gas neutral, but also neutral with respect to all other human-induced changes that affect the climate.9 However, it doesn’t necessarily mean that emissions are completely reduced, or that there are no emissions initially generated. Climate neutrality also involves offsetting the greenhouse gases generated through financial support for climate and environmental protection measures, initiatives, and projects.10
However, the term climate-neutral often leads to accusations of greenwashing. A major challenge is that it does not specify how much of the emissions can be proportionally offset through financial participation in climate projects, and how much must be directly reduced. To use the term climate-neutral, organizations must only compensate for their own emissions, such as those from company vehicles or purchased energy, not taking into account their indirect emissions that occur throughout their value chain.
Net zero
Net zero goes one step further than carbon neutrality, and offsetting alone is not enough to achieve net-zero emissions. Put simply, net zero means reducing human-caused greenhouse gas emissions to as close to zero as possible. The remaining emissions must be re-absorbed from the atmosphere by natural sinks, like oceans and forests, or artificial sinks, such as carbon capture and storage technologies. Just like carbon neutrality, net zero refers only to human-induced greenhouse gas emissions.
Many countries, cities, businesses, and other institutions have pledged to achieve net-zero emissions by 2050. Among them are countries and regions with the highest pollution levels – China, the United States, and the European Union.12
Circular carbon economy
The circular carbon economy aims to manage carbon emissions to reduce carbon in the first place, to reuse and recycle carbon as a source for feedstocks and renewable fuels, and to remove excess carbon and store it. New technologies can support this cause by closing the carbon cycle for certain industrial processes where the generation of CO2 is difficult or impossible to avoid. These are, for example, technologies for carbon capture and storage, as well as technologies that can recycle and reuse CO2, such as for the production of renewable fuels.13
In an era where every individual, organization, and country plays a pivotal role in our shared quest for sustainability, understanding these terms acts as a compass guiding our actions. It empowers us to engage in meaningful dialogues, set clear expectations, and hold ourselves and others accountable in building a sustainable future.
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Sources:
[1] un.org/en/climatechange/what-is-climate-change
[2] goclimate.de/glossar/co2
[3] climatepartner.com/de/wissen/insights/scope-emissionen-reduzieren
[4] iea.org/reports/co2-emissions-in-2023
[5] wri.org/insights/6-ways-remove-carbon-pollution-sky
[6] firstclimate.com/was-ist-ein-co2-fussabdruck
[7] myclimate.org/en/information/faq/faq-detail/what-does-decarbonisation-mean
[8] global-climate.de/en/compliance-2/climate-neutrality-net-zero
[9] global-climate.de/en/compliance-2/climate-neutrality-net-zero
[10] weforum.org/agenda/2019/06/what-is-carbon-offsetting
[11] global-climate.de/en/compliance-2/climate-neutrality-net-zero
[12] un.org/en/climatechange/net-zero-coalition
[13] cceguide.org/de/guide
