An environmental impact is an impact that an activity has on the environment through the emissions or use of resources that it causes. In the context of life cycle assessment (LCA), an environmental impact has been defined in EC-JRC (2011) as:
“Potential impact on the natural environment, human health or the depletion of natural resources, caused by the interventions between the technosphere and the ecosphere as covered by LCA (e.g. emissions, resource extraction, land use).”
Environmental effect, environmental damage, and environmental consequence are sometimes used as synonyms of environmental impact although they are located later in the causality chain that links an activity to its consequences. The activity (e.g., burning of fossil fuels) may cause an impact (e.g., increase of the concentration of the greenhouse gas carbon dioxide in the atmosphere) that leads to an effect (increased radiative forcing of the atmosphere) that as a consequence has an increased global average temperature in the atmosphere which as a consequence has sea level rise leading to damage to coastal land ecosystems Some confusion about the terms stems from the fact that the effect of one impact becomes in itself an impact with other effects and so forth along the cause-effect chain.
Impacts that are causally linked and contribute to a known environmental issue or theme are combined in an impact category, where they are represented by an impact indicator chosen somewhere along the impact pathway.
Understanding of the impact pathway is fundamental for deciding whether an impact belongs to the category and to know whether different impacts are complementary or just two different links in the same impact chain (i.e., one leads to the other).
For the use in LCA, several default lists of impact categories have been produced over the years. The latest authoritative list is from the European Commission’s ILCD Guidelines, and it operates with the following categories:
- Climate change
- Ozone depletion
- Human toxicity, cancer effects
- Human toxicity, noncancer effects
- Particulate matter/respiratory inorganics
- Ionizing radiation, human health
- Ionizing radiation, ecosystems
- Photochemical ozone formation
- Acidification
- Eutrophication, terrestrial
- Eutrophication, aquatic
- Ecotoxicity
- Land use
- Resource depletion, water
- Resource depletion, mineral, fossil, and renewable
Impacts on biodiversity are also a strong concern in times where the rate of species extinction is elevated high above previous levels. In the cause-effect chains, impacts on biodiversity are typically located toward the end, where damage on ecosystems and habitats occurs.
