Despite this rapid growth, greenhouse gas emissions from aviation are currently excluded from any restrictions under the Kyoto Protocol. (Domestic aviation is included in national emissions targets.)
The IPCC also reported that data from the International Civil Aviation Organization (ICAO) revealed that "aviation scheduled traffic (revenue passenger-km, RPK) has grown at an average annual rate of 3.8% between 2001 and 2005 despite the downturn from the terrorist attacks and SARS (Severe Acute Respiratory Syndrome) during this period, and is currently growing at 5.9% per year."[1]
The IPCC noted that Airbus and Boeing projected "passenger traffic growth trends of 5.3% and 4.9% respectively, and freight trends at 5.9% and 6.1% respectively over the next 20 or 25 years". It concluded that "these forecasts and others predict a global average annual passenger traffic growth of around 5% – passenger traffic doubling in 15 years – with freight traffic growing at a faster rate that passenger traffic, although from a smaller base."[1]
Modeling cited by the IPCC estimated that aviation emissions were approximately 492 million tonnes of carbon dioxide and 2.06 million tonnes of nitrogen oxide in 2002 and will increase to 1029 and 3.31 million tonnes respectively by 2025.[1]