Preserving carbon dioxide removal to serve critical needs

Abstract

Carbon dioxide removal (CDR) is critical to most net-zero pathways, especially given challenges due to slow decarbonization, hard-to-abate (H2A) economic activities and non-CO2 GHGs. However, land-based CDR, which is the most widely deployed currently and in future projections, requires extensive land and water. Here we examine least-cost 1.5 °C overshoot pathways, finding that 78 of 81 scenarios would require all available sustainable CDR to compensate for H2A emissions and overshoot. Use of CDR to compensate for emissions from easier-to-decarbonize sectors such as electricity would leave less available to compensate for H2A emissions, increasing system-wide costs of net zero or rendering such goals impossible. Such usage, however, is allowed in many jurisdictions and is widespread in voluntary markets. We suggest that rapidly transitioning CDR usage to exclusively compensate for H2A emissions and overshoot is required to prevent lower costs for near-term actors leading to larger long-term system-wide costs. Land-based carbon dioxide removals are critical for meeting the low-warming targets, yet their availability is limited when avoiding excessive risks to sustainability. Scenario-based analysis suggests that they should only be used to compensate for emissions from hard-to-abate sectors and overshoot.