CORSIA, the Carbon Offsetting and Reduction Scheme for International Aviation, addresses the increase in total CO2 emissions from international aviation above 2020 levels. 

CORSIA’s obligations have already started. As of 1 January 2019, all carriers are required to report their CO2 emissions on an annual basis.

The aviation industry is committed to technology, operational and infrastructure advances to continue to reduce the sector’s carbon emissions. Offsetting is not intended to replace these efforts. Nor would the CORSIA make fuel efficiency any less of a day-to-day priority. 

It is forecast that CORSIA will mitigate around 2.5 billion tonnes of CO2 and generate over USD 40 billion in climate finance between 2021 and 2035.

https://www.iata.org/policy/environment/Pages/corsia.aspx