We Need the Largest Experiments on Earth to Achieve Our Climate Targets.

Natural Climate Solutions (NCS) are the climate mitigation sector with the largest potential, yet the least investment. A major barrier to scaling NCS is lack of evidence-based scientific learning at the scale of actual interventions. To overcome this gap, we propose the world's largest field experiments, supported by a global data-sharing platform and guided by a clear framework of ethical principles and guidelines for delivering robust NCS evidence. This involves consistently reporting outcomes in units of MgCO2e $-1 yr-1 while describing direct and enabling actor groups and their financial, policy, and information interactions.