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-of-century 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 required to give valuable insights into optimal CDR-based mitigation pathways regarding scalability, technology readiness, trade-offs with earth systems, and deployment strategies. Here, we have used the GCAM-CDR 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 CDRs relies heavily on significant emission reductions in the industrial and hard-to-abate sectors. Finally, we observed that nuclear energy will be an important energy resource for these 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 The EU needs to develop a more comprehensive CDR strategy; with bioenergy and nuclear energy playing a vital role and DACCS developing later.