As IATA has indicated, these figures represent costs of the same order as present environmental levies already in place in some countries, which IATA anticipates would be withdrawn when a global MBM agreement is in place. The results of the ICAO study have been corroborated by a further MMU CATE study that concludes MBMs are the quickest and most effective way to reduce aviation CO2 emissions (Lee et al. 2013b).