The findings of atmospheric chemistry about the accumulation of anthropogenic gases in the atmosphere and their influence on ozone depletion and ultimately on the climate on our planet led to the adoption of the Montreal and Kyoto Protocols on Greenhouse Gases (GHG) and their mitigation and avoidance. As a result, the concept of the Product Carbon Footprint (PCF) evolved to determine the GHG emissions caused by a product and ultimately by an organization. Introduced at the beginning of the 2000s the GHG Protocol developed by WRI and WBCSD became the de facto standard therefor. Emissions are categorized into three scopes to give companies the opportunity to specifically quantify and mitigate their emissions. The Together for Sustainability (TfS) initiative is further developing and substantiating the GHG Protocol for the chemical and plastics industry with its complex value chains. The focus is on methodological approaches for the reliable and comparable calculation of the PCF in the context of a life cycle assessment (LCA) as well as for the verification of the results to make them reliably available and manageable for internal company measures as well as for use in the market and towards policymakers and regulators.