Comparison of carbon management and emissions of universities that did and did not adopt voluntary carbon offsets

The urgent need to reduce greenhouse gas emissions, remove carbon from the atmosphere and stabilize natural carbon sinks has led to the development of many carbon management measures, increasingly including voluntary carbon offsets (VCOs). We studied carbon management in universities, institutions with large carbon footprints and considerable influence in climate science and policy fora. However, concerns that VCOs may deter adopters (including universities) from adopting other carbon reduction measures and limit emissions reductions, for example, through moral hazard, have been raised but understudied. We compared the carbon management characteristics (priorities, policies, practices and emissions) of universities that did and did not adopt VCOs. We found adopters measured carbon emissions for longer, and had set targets to reach net zero earlier than had non-adopters. Adopters of VCOs also undertook more carbon management practices in both 2010 and 2020 than non-adopters. We also found that both adopters and non-adopters significantly increased their carbon management practices over the decade studied, but with no difference between groups. Gross CO₂ emissions were reduced significantly over time by adopters of VCOs but not by non-adopters, whereas carbon intensity and percentage annual emissions reductions did not relate to adoption status. Consequently, our study showed no indication of mitigation deterrence due to adoption of VCOs at the universities studied. Rather, greater emissions reductions correlated with earlier net zero target dates, and a higher number of policies and carbon management practices. However, our study was constrained to universities that were affiliated with a national environmental network, so research beyond these organizations, and with individuals, would be useful. The survey was voluntary, exposing the study to potential self-selection bias so the findings may not be generalized beyond the study group. Finally, we found the carbon accounting method currently required of universities for scope 1 and 2 emissions may underestimate emissions reductions, particularly for adopters of VCOs. Augmenting the current location-based accounting method with market-based carbon accounts may overcome this. Adopters of voluntary carbon offsets (VCOs) undertook more carbon management practices than non-adopters. Evidence for mitigation deterrence was therefore not found (e.g. via moral hazard).Both adopters and non-adopters of carbon offsets used mitigation hierarchies found in carbon management literature (measure, reduce then offset). However, clarity on reducing emissions to as low as reasonably practicable is lacking in the literature.Reductions in scope 1 and 2 emissions may be underestimated, especially for adopters of VCOs who adopted more practices not included in current carbon reporting (e.g. purchasing renewable energy). This may be overcome by reporting market-based emissions alongside location-based emissions. Adopters of voluntary carbon offsets (VCOs) undertook more carbon management practices than non-adopters. Evidence for mitigation deterrence was therefore not found (e.g. via moral hazard). Both adopters and non-adopters of carbon offsets used mitigation hierarchies found in carbon management literature (measure, reduce then offset). However, clarity on reducing emissions to as low as reasonably practicable is lacking in the literature. Reductions in scope 1 and 2 emissions may be underestimated, especially for adopters of VCOs who adopted more practices not included in current carbon reporting (e.g. purchasing renewable energy). This may be overcome by reporting market-based emissions alongside location-based emissions.当前亟需减少温室气体排放、清除大气中的碳并稳定自然碳汇，这推动了诸多碳管理举措的发展，其中日益纳入自愿碳抵消（voluntary carbon offsets, VCOs）。本研究聚焦高校这类碳足迹庞大、且在气候科学与政策论坛中具备显著影响力的机构的碳管理实践。然而，学界已提出担忧：自愿碳抵消可能会阻碍包括高校在内的采用者采取其他碳减排措施，并通过道德风险等途径限制减排成效，但相关研究仍较为匮乏。 我们对比了采用与未采用自愿碳抵消的高校的碳管理特征（包括优先级、政策、实践与碳排放情况）。研究发现，采用自愿碳抵消的高校更早开展碳排放测量，并更早制定净零排放（net zero）目标。相较于未采用者，采用者在2010年与2020年均实施了更多碳管理实践。我们还发现，在本研究覆盖的十年间，两类高校的碳管理实践均实现了显著增长，但两组间并无显著差异。采用自愿碳抵消的高校的总CO₂排放量随时间显著降低，而未采用者则未出现此变化；不过碳强度与年度减排百分比与是否采用自愿碳抵消并无关联。 因此，本研究未发现所考察高校因采用自愿碳抵消而出现减排阻碍的迹象。相反，更早设定净零排放目标、制定更多政策与碳管理实践，与更显著的减排成效相关。但本研究的样本仅局限于隶属于国家环境网络的高校，因此针对其他组织乃至个人开展相关研究将具有重要价值。本次调查为自愿参与，本研究存在潜在的自选择偏差（self-selection bias），研究结论或无法推广至本研究群体之外。 最后，我们发现当前要求高校针对范围1和范围2排放（scope 1 and 2 emissions）采用的碳核算方法，可能低估了减排成效，尤其对于自愿碳抵消采用者而言。将基于市场的碳核算方法与当前的基于地点的核算方法相结合，或可解决这一问题。 自愿碳抵消采用者较未采用者实施了更多碳管理实践。因此，本研究未发现减排阻碍的相关证据（例如通过道德风险途径）。两类碳抵消采用者与未采用者均采用了碳管理文献中提及的减排层级：测量、减排再抵消。但现有文献尚未明确如何将排放降至合理可行的最低水平。范围1和范围2排放的减排量或被低估，尤其是采用了更多当前碳报告未涵盖的实践（例如采购可再生能源）的自愿碳抵消采用者。通过同时报告基于市场的排放量与基于地点的排放量，或可解决这一问题。 自愿碳抵消采用者较未采用者实施了更多碳管理实践。因此，本研究未发现减排阻碍的相关证据（例如通过道德风险途径）。两类碳抵消采用者与未采用者均采用了碳管理文献中提及的减排层级：测量、减排再抵消。但现有文献尚未明确如何将排放降至合理可行的最低水平。范围1和范围2排放的减排量或被低估，尤其是采用了更多当前碳报告未涵盖的实践（例如采购可再生能源）的自愿碳抵消采用者。通过同时报告基于市场的排放量与基于地点的排放量，或可解决这一问题。