Countries banking too heavily on future carbon dioxide removal (CDR) to meet climate targets could be violating international legal obligations, according to a new study led by University of Oxford researchers.
The paper argues that while CDR, which includes technologies and nature-based methods that remove CO2 from the atmosphere, will be necessary, treating it as a substitute for rapid emissions cuts risks breaching established legal principles.
The researchers highlight “legal guardrails” drawn from international law, including the harm prevention principle and due diligence standards clarified by the International Court of Justice’s 2025 climate advisory opinion. These standards, they say, require states to pursue deep, near-term emissions reductions and take a precautionary approach to the uncertainties surrounding large-scale CDR deployment. Overreliance on future removals could lead to dangerous overshoot of the Paris Agreement’s 1.5°C goal: something states are legally obliged to minimise.
“In an uncertain world, some states are gambling on the future deployment of CDR techniques to meet their climate targets in place of more ambitious near-term mitigation measures,” said professor Lavanya Rajamani of Oxford’s Faculty of Law. “Our findings emphasise that near-term emissions reductions and feasible CDR strategies are not only ethical imperatives; they are legal requirements.”
Co-author Rupert Stuart-Smith added that many national strategies rely on assumptions about technologies that may not materialise. “Legal guardrails are essential to avoid passing climate risks on to future generations and to ensure that CDR does not substitute for the emissions reductions urgently needed now,” he said.
The study distinguishes between substantive guardrails such as prioritising emissions cuts over removals, ensuring CDR approaches are technically and socially feasible, and limiting reliance on international credits and procedural ones, including transparency about emissions projections, CDR types and modelling assumptions. The authors conclude that many existing national plans fall short of these standards, and that international law already provides a framework to assess the credibility of climate strategies.
Published in Climate Policy, the research is a collaboration between Oxford, Imperial College London and other European institutions, and comes amid record global temperatures and growing debate over the role of carbon removal in net-zero pathways. The authors argue that aligning climate plans with these legal guardrails will require far greater emphasis on immediate emissions reductions and more realistic, transparent use of CDR.