We propose a one–band XCO₂ retrieval technique which uses only the 2.06 µm band measurements from the Orbiting Carbon Observatory–2 (OCO–2) satellite. Compared to the current state–of–the–art three–band retrievals, XCO₂ retrievals using only the 2.06 µm band have similar retrieval accuracy, precision, and data yield. For future missions it may be better to replace the O₂ A band with measurements that have larger information content on aerosols, like a multi–angle polarimeter (MAP).