Climate change is an impact category in Life Cycle Impact Assessment that represents the potential contribution of greenhouse gas emissions to alterations in the Earth's climate system. Within the LCA framework defined by ISO 14040 and ISO 14044, climate change is one of the most widely assessed environmental impact categories, reflecting growing concern about anthropogenic influences on global climate patterns.
In LCIA methodology, climate change impacts are typically quantified by converting various greenhouse gas emissions into carbon dioxide equivalents (CO₂-eq) using characterisation factors that reflect their relative global warming potential over a specified time horizon. The most commonly used time horizons are 20, 100, or 500 years, with the 100-year horizon being the default in most impact assessment methods. These characterisation factors account for both the radiative forcing efficiency of each greenhouse gas and its atmospheric lifetime.
The climate change impact category encompasses emissions of various greenhouse gases, including carbon dioxide (CO₂), methane (CH₄), nitrous oxide (N₂O), and fluorinated gases such as hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), and sulphur hexafluoride (SF₆). Each of these gases contributes differently to radiative forcing and persists in the atmosphere for different durations, which is reflected in their respective characterisation factors.
Climate change represents a midpoint impact category indicator that can be further linked to endpoint indicators reflecting damage to human health, ecosystem quality, and resource availability. At the endpoint level, climate change contributes to impacts such as heat-related mortality, changes in disease vector distributions, loss of biodiversity, sea level rise, and changes in agricultural productivity. These connections between midpoint and endpoint indicators are established through characterisation models that describe the cause-effect chain from emissions to ultimate damages.
The assessment of climate change in LCA is particularly important for comparing product systems with different energy sources, production processes, or transportation requirements, as these factors often drive significant differences in greenhouse gas emissions across a product's life cycle.
