Sustainability implications of different carbon dioxide removal technologies in the context of Europe's climate neutrality goal

The role of carbon dioxide removal (CDR) is undoubtedly crucial in achieving the climate goals and end-ofcentury global warming target. Given its role as a leader in global climate actions, the European Union (EU) is expected to take a leading role in CDR developments: yet there is a lack of depth in the region's CDR strategy and deployment. A comprehensive CDR approach based on integrated assessment modelling for the EU is important to give valuable insights into optimal CDR-based mitigation pathways regarding scalability, technology readiness, trade-offs with the Earth system, and deployment strategies. Here, we have used the GCAMCDR v1.0 to model a diverse novel CDR portfolio of bioenergy carbon capture and storage (BECCS), direct air capture and carbon storage (DACCS), terrestrial enhanced weathering (TEW), and ocean-enhanced weathering (OEW) in a mid-century carbon neutrality target. We find that CO2 removal by BECCS scales quickly to gigatonnes of CO2 removal by mid-century, and DACCS is a latter-century mitigation technology in the EU's emission mitigation pathway. TEW will play a crucial role in achieving carbon neutrality in the EU if this climate goal is advanced by a decade. Modelled results show that achieving carbon neutrality through diverse CDR relies heavily on significant emission reductions in the industrial and hard-to-abate sectors. Finally, we observed that nuclear power will be an important energy resource for the energy-consuming CDR technologies in Europe. This study recommends that the EU carbon removal structure should not be limited to DACCS, but rather allow for innovations in carbon removal technologies. Synopsis: Achieving the EU's carbon neutrality targets requires a diversified Carbon Dioxide Removal (CDR) strategy, with BECCS identified as a scalable solution by mid-century and nuclear energy as a key support for energy-intensive CDR technologies.