Global Warming Potential (GWP)
Global Warming Potential, GWP, is a measure of how much heat a greenhouse gas traps in the atmosphere over a specific time period (usually 100 years), relative to the same amount of carbon dioxide (CO2). It is way to compare the "warming power" of different gases. CO2 has a GWP of 1, while other gases like methane have much higher GWPs, meaning they trap significantly more heat than CO2 over the same timeframe.
In current LCA standards like EN 15804+A2 and the underlying EF 3.1 method a number of sub-categories of GWP is reported to provide more nuanced information about the sources of greenhouse gas emissions:
GWP total: refers to the sum of the global warming potential from all relevant greenhouse gas emissions throughout the life cycle of a product, typically over a 100-year time horizon (GWP100).
GWP fossil: This indicator accounts for the greenhouse gas emissions originating from the extraction and burning of fossil fuels (like oil, coal, and natural gas) and from materials containing fossil carbon. It also includes emissions from processes like calcination and removals from carbonation of materials
GWP biogenic:This indicator focuses on the impact of carbon dioxide (CO2), and methane (CH4) emissions and removals from biological sources (biomass), excluding native forests. It considers the CO2 absorbed by biomass during growth (a negative value, indicating removal from the atmosphere) and the CO2 released when the biomass is burned or decays (a positive value, indicating emissions).
GWP land use:This indicator assesses the greenhouse gas emissions and removals (including CO2, CO, and CH4) that result from changes in land use. This includes activities like deforestation, afforestation, or changes in soil carbon stocks due to different land management practices. It captures the impact of how human activities alter the carbon stored in vegetation and soil.
GWP GHG: This is calculated based on the standard set of greenhouse gases reported under international protocols like the Kyoto Protocol or IPCC, includes gases like carbon dioxide (CO2 ), methane (CH4 ), nitrous oxide (N2 O), and fluorinated gases (HFCs, PFCs, SF6). This indicator accounts for all greenhouse gases except biogenic carbon dioxide uptake and emissions and biogenic carbon stored in the product. As such, the indicator is identical to GWP-total except that the CF for biogenic CO2 is set to zero.This allows for comparison of results between comparable products in different EPDs without having to consider the biogenic content in product and packaging.