Despite the urgent need for becoming more sustainable and enhancing sustainability reporting induced by, e.g., the Corporate Sustainability Reporting Directive effective from January 2024, there exists a lack in research and industry efforts for integrating sustainability metrics into business processes. One particular reporting requirement entails that large EU companies must disclose their sustainability metrics for greenhouse gas (GHG) emissions across their supply chains. To address this challenging task, this paper presents the Process Mining Guidelines for Greenhouse Gas Emission Management (PMG3), helping companies implement process mining to meet GHG emissions targets in production processes. Thereby, the PMG3 provides detailed steps for defining business and data requirements, analyzing inefficiencies, and formulating recommendations to enhance sustainability reporting. To validate PMG3, a detailed demonstration was conducted using real-world data from a business case in the production process within the consumer goods industry. The utility evaluation revealed high approval for the PMG3's usefulness, ease of use, and practitioners’ intention to use it in industry settings. Overall, this paper contributes a structured and applied approach for organizations to report GHG emissions and improve sustainability performance through process mining.