Carbon Dioxide Removal (CDR) is essential to meet the Paris Agreement’s commitment to stay below a 1.5 degrees Celsius average temperature increase. To provide critical foundational support to the development, deployment, and scaling of CDR, certification of carbon removal is needed. The international community is developing rules for the functioning of carbon markets. To support that process, we explored open questions on four key themes in the development of standards and certification of carbon removal through an international multi-stakeholder consultation process hosted by the Global Carbon Removal Partnership, Arizona State University, and Conservation International. Categories of stakeholders included standard developing organizations, non-governmental organizations, governments, and academics. Discussions covered 1. the treatment of emission reduction, avoidance,and removal in certification, 2. the role of additionality in carbon removal, 3. the choice of certification instrument for carbon removal, and 4. the treatment of durability in certification. They revealed fundamental differences in viewpoints on how certification should work. We highlight areas of further exploration, concluding that providing transparency on assumptions made at the certification level will be crucial to progress and, eventually, the acceptance and success of carbon removal as a climate solution.