Reaching climate neutrality and limiting the global average temperature increase to 1.5 °C, which are the main targets of the Paris Agreement, requires both mitigation measures and offsetting. Despite existing standards to ensure the credibility and effectiveness of carbon offsets, they face challenges associated with their quality. Incorrect replacement factors or baseline values used for the calculations can lead to credits being overestimated. The quality of carbon offsets and its assurance through offsetting standards are addressed in many publications that provide quality criteria that should be fulfilled. However, the abundance of studies and the unclear consistency of quality criteria for carbon offsets make it difficult to draw generalized conclusions. The fragmented understanding of offset quality and its contribution to climate neutrality requires a comprehensive analysis to identify prevailing consensus and areas needing further research. The paper aims to fill this gap by synthesizing existing criteria through a qualitative meta-analysis of the current literature. Consensus and discrepancies in the carbon offset quality criteria and the ratings of the offsetting programs were identified providing a holistic overview. While only the criteria 'additionality' and 'permanence' are consistently addressed in all publications, their definitions and associated aspects vary. Although consensus exists for the criterion 'ex-post', it only appears in 57% of the publications. Differences in definitions are not reflected in the program ratings. The analysis has several challenges, such as accommodating varying study scopes and methods. However, the results highlight the need for a common understanding and provide a baseline reference to enhance the quality assessment of offsets to effectively contribute to climate neutrality.
Keywords: Carbon offset; Climate neutrality; Offsetting programs; Offsetting quality; Qualitative meta-analysis; Quality criteria.
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