The forecast came at this week’s environment summit, held by the Air Transport Action Group (ATAG), in Montréal.
ATAG’s executive director, Paul Steele, said steps towards agreeing a worldwide “market based measure” could be announced at the International Civil Aviation Organization (ICAO) assembly later this year. A final agreement is then likely to be announced at ICAO's 2016 assembly.
The EU “stopped the clock” on its controversial Emissions Trading Scheme for flights into and out of Europe, giving ICAO until this September to show it had made “significant progress” towards a global solution.
The High-level Group on International Aviation and Climate Change (HGCC) met in March to work towards a deal and will meet again in June or July, ahead of ICAO’s assembly in September.
The HGCC is represented by 17 nations, including the US, the UK, Russia, China, and France.
Steele said the preferred scheme would involve airlines buying carbon credits to offset any emissions growth over and above 2020 levels.
He said environment would be “the key issue on the agenda” at the ICAO assembly.
He added: “It is certainly the most challenging as governments come together to address aviation emissions and craft a global solution.
“The big issue and the most divisive is this question of a market based measure.
“We have to remember that ICAO has 192 members states that must agree on a way forward.”
The alternative to a market based system would be that each state comes up with its own measures.
Steele said this would lead to a “patchwork approach” which would be “in no one’s interest”.
He said technology, low-carbon fuel and a market based measure should all play their part in reducing emissions.
Asked whether the progress announced in September would be enough to satisfy the EU, Steele said: “That’s the $64 million question. Europe needs to be given credit because they have raised this issue up the agenda.
“However, the fact that they extended the scope to include flights between Europe and other places – we don’t believe they did it in the right way.
“I would not share the view that ICAO has dragged its feet on this issue.”
In 2009, the global aviation industry agreed a set of ambitious targets to reduce its CO2 impact.
It will cap its net CO2 from 2020 through carbon-neutral growth and halve its net CO2 emission by 2050, based on 2005 levels.
About 200 delegates from 44 countries met in Montréal for ATAG’s Aviation and Environment Workshop.