AM0021 is a baseline methodology for the decomposition of nitrous oxide (N2O) from existing adipic acid production plants. This methodology, approved under the Clean Development Mechanism (CDM), aims to reduce greenhouse gas emissions by implementing N2O abatement technologies. Initially, it was applicable only to existing plants, but revisions have extended its applicability to new plants as well​ (CDM UNFCCC) (Zoro)​.