The research data infrastructures in the Earth System Sciences (ESS) are highly diverse, featuring numerous data repositories and metadata aggregators with varying standards, which complicates the provision of essential cross-infrastructure services. The NFDI4Earth Label aims to enhance the interoperability and trustworthiness of these repositories by developing clear repository guidelines and a certification process tailored to the ESS community. Unlike existing certifications, the NFDI4Earth Label emphasizes ESS-specific metadata standards and is achievable for smaller repositories, ensuring relevance and practical applicability. Developed in collaboration with the ESS community and aligned with European Open Science Cloud (EOSC) initiatives, the NFDI4Earth Label seeks to foster a more integrated and trustworthy research data landscape in the ESS.