Climate impact of delayed carbon dioxide removal by a single emitting entity to compensate for their legacy emissions

Carbon dioxide removal (CDR) is increasingly recognized as a key component of climate strategies to offset unabatable residual emissions on the path to net zero. In recent years, corporations in particular have shown growing interest in using CDR to offset their historical or “legacy” emissions. However, the prevailing assumption that one tonne of CO 2 removed today cancels a tonne emitted in the past neglects the temporal mismatch between emissions and removals, during which CO 2 exerts a warming effect. This paper considers specific entities that emit a very small fraction of global emissions, have a net-zero carbon goal and pledge to compensate for their legacy emissions. It examines the effectiveness of such compensation through climate consequences of delayed CDR, arguing that a simple mass-balance approach may not be sufficient. Using a simplified linear climate model, we analyze the impact of the timing and rate of CDR deployment on two complementary climate metrics: peak surface temperature and abyssal ocean temperature anomaly, reflecting direct short-term and long-term cumulative impacts, respectively. Our results show that earlier CDR deployment, even at slower rates, yields a more favorable climate outcome than delayed, faster deployment. The analysis also reveals that removing more CO 2 than was originally emitted can help mitigate the effects of delayed action, particularly for long-term climate impacts. These findings highlight the importance of accounting for temporal dynamics in climate mitigation strategies. Our work aims to inform corporate climate policies and encourage further scientific discourse on the dynamic effects of legacy emissions and legacy removals.