After six years of back-and-forth negotiations, a global initiative to limit greenhouse gas emissions was recently agreed upon by the United Nations Aviation Agency. The plan, which is officially known as the Carbon Offset and Reduction Scheme for International Aviation (CORSIA), will require carbon-neutral growth for both commercial and cargo airlines beginning in 2021. Airlines whose emissions exceed 2020 levels will be forced to purchase carbon-offset credits to mitigate that increase. The plan was agreed upon by the 191-member International Civil Aviation Organization (ICAO). Voluntary implementation will begin in 2021, with 65 countries, including the United States and European Union, already agreeing to participate. Mandatory implementation will begin in 2028.