At COP27, countries are supposed to agree on a high-level definition of greenhouse gas removals, including setting out provisions to address monitoring, permanence (whether the carbon is stored on a “permanent” basis), and reversals (when the carbon is re-released into the atmosphere, such as due to a forest fire). Non-permanence in land-based activities is particularly problematic. Institutional processes to try to address this, such as establishing buffer pools or insurance mechanisms, are either too short (for example, less than 100 years) or unrealistic (such as guaranteeing the existence and operation of a buffer pool for over 100 years), and sometimes both. Tonne-year accounting is a particularly dangerous idea whereby storing 100 tonnes for 1 year could create a credit equivalent to storing 1 tonne for 100 years. From a carbon-budget perspective, storing carbon for a short amount of time has no benefit. Storing carbon for a medium amount of time (several decades) could have benefits but should not be seen as equivalent with emission reductions. Tonne-year accounting must not be included as a possibility in the definition of removals in 6.4. The definition of removals to be agreed at COP27 will have significant implications for Article 6.4, and even beyond in terms of sending a signal to the voluntary carbon market. Therefore, it is crucial that countries properly define removals. A removal must: i) lead to a net reduction of GHGs in the atmosphere; ii) actually absorb carbon out of the atmosphere; iii) be comprehensively accounted for, including all emissions generated through the removal process; and iv) be stored for a climate-relevant timescale (at least 200-300 years). These are principles based on a paper by Tanzer and Ramirez.