A prudent planetary limit for geologic carbon storage.

Geologically storing carbon is a key strategy for abating emissions from fossil fuels and durably removing carbon dioxide (CO) from the atmosphere. However, the storage potential is not unlimited. Here we establish a prudent planetary limit of around 1,460 (1,290-2,710) Gt of CO storage through a risk-based, spatially explicit analysis of carbon storage in sedimentary basins. We show that only stringent near-term gross emissions reductions can lower the risk of breaching this limit before the year 2200. Fully using geologic storage for carbon removal caps the possible global temperature reduction to 0.7 °C (0.35-1.2 °C, including storage estimate and climate response uncertainty). The countries most robust to our risk assessment are current large-scale extractors of fossil resources. Treating carbon storage as a limited intergenerational resource has deep implications for national mitigation strategies and policy and requires making explicit decisions on priorities for storage use.