Improving monitoring protocols for CO 2 geological storage with technical advances in CO 2 attribution monitoring

•Attribution techniques can confirm whether CO2 at surface is leakage or not.•Suspected leakage should not be quantified unless first confirmed using attribution.•Monitoring protocols either omit attribution or they suggest outdated methods.•CO2 attribution techniques have recently advanced from operational experience.•Monitoring protocols should include, update, and clarify attribution monitoring.