ICAO Secretary General Raymond Benjamin says he's optimistic that a global accord will be approved by 191 member countries, setting the stage for a final vote before the 2020 implementation.
"I can assure you that we are totally confident that by the end of this assembly we will have reached a global accord on this question," he said at an opening news conference at the International Civil Aviation Organization headquarters.
Aviation accounts for two per cent of global man-made carbon dioxide emissions, but leaders want to restrict the environmental impact of an expected doubling of passenger demand by 2030. In 2009, the global aviation industry agreed to cap its net emissions from 2020 through "carbon-neutral growth'" and halve its net CO2 emissions by 2050, based on 2005 levels.
Efforts to achieve a global emissions resolution were dashed three years ago, setting the stage for the European Union to propose an Emissions Trading Scheme last year that was put on hold following threats of trade wars from unhappy governments.
"I think we are in a much better position this time than three years ago," said ICAO Council president Roberto Kobeh Gonzalez, referring to a draft resolution approved by the governing council.
Benjamin also told reporters that greater efforts must be taken to avoid terrorist acts at airports and in the skies, such as relying on more sophisticated equipment to detect plastic and liquid explosives.
He also supports a risk-based approach to airport security that would assess threat levels by travellers and cargo on an individual basis.
In a video address, United Nations Secretary General Ban Ki-moon told delegates that they were central to the world's climate change and sustainability agenda.
"Climate change is a threat to economies large and small, to the development and well-being of societies everywhere and to the health of the planet," he said, noting that he will convene a climate summit next year.
"The longer we delay, the greater the costs... I count on this meeting to explore how the aviation sector can limit carbon emissions and contribute to sustainable development."
Earlier, Canadian Transport Minister Lisa Raitt told the assembly that many of the issues on its agenda are "ambitious," particularly on controlling emissions.
"Many of the issues on this, the 38th assembly’s agenda, are not easy. Innovation rarely is," she said. "We must all strive to improve the already high standards in safety and security and to improve the economic viability of our sector in these challenging global economic times."
Raitt and Quebec Premier Pauline Marois also praised ICAO's decision to maintain its headquarters in Montreal at least until 2036 despite an effort by Qatar, since abandoned, to have it moved to the Middle East.