  Unless there is immediate, unprecedented, reduction in global demand for
carbon-intensive energy and products, then capture and permanent storage of
billions of tonnes of carbon dioxide (CO2) annually will be needed before
mid-century to meet Paris Agreement goals. Yet competition from cheaper,
temporary, carbon storage means that permanent disposal remains starved of
investment, currently representing about 0.1% of Energy and Industrial Process
(EIP) emissions. This stored fraction must reach 100% to stop EIPs causing
global warming. Here we show that a cost-effective transition can occur by
mandating an increasing stored fraction through a progressive Carbon Takeback
Obligation (CTO) on fossil fuel producers and importers. Projected costs of
storage to the consumer are lower than pricing carbon emissions in conventional
1.5{\deg}C scenarios until the 2040s, and comparable or lower thereafter. A CTO
combined with measures to reduce CO2 production would deliver the lowest-risk
pathway to achieving net zero.
