Airlines’ efforts to reduce their carbon emissions will be front and center at the UN aviation agency’s annual conference, which opened on Tuesday days before a major climate protest in Montreal to be attended by teen activist Greta Thunberg.

The International Civil Aviation Organization’s 193 member states will take stock of the implementation of a climate plan unveiled at its last general assembly in 2016.

Under the so-called Carbon Offsetting and Reduction Scheme for International Aviation (CORSIA), participating airlines are expected to stabilize their CO2 emissions by 2020, and buy offsetting credits thereafter if they exceed set limits.

Airlines and plane manufacturers had agreed in 2009 to cut emissions by 50 percent from 2005 levels by 2050.

The European Union wants to go further and blend CORSIA with its own regulations.

“Talks are likely to be tense,” a well-informed source told AFP on condition of anonymity.

For their part, airlines have called on governments to reaffirm their support for CORSIA during the ICAO meeting and to “make it a success.”

“We have seen perhaps the desperation of young people, we hear the calls to reduce air travel, even to stop flying. We say it is possible both to fly and reduce our carbon footprint,” Alexandre de Juniac, director general of the International Air Transport Association, told a news conference on Tuesday.

He cited better jet engines and improved air traffic controls, adding that the development of cleaner jet fuels could reduce aviation’s carbon footprint by up to 80 percent.

Coinciding with the ICAO meeting in Montreal, world leaders gathered in New York this week for a UN climate summit.

On Monday, Swedish teen Greta Thunberg — after sailing across the Atlantic to avoid flying — accused world leaders of betraying her generation by failing to tackle greenhouse gas emissions.

ICAO Secretary-General Fang Liu was open to a meeting with the 16-year-old activist, a spokeswoman for the institution said. But no meeting has been scheduled.

Aviation accounts for about two percent of global greenhouse gas emissions, according to the ICAO. Airlines transported 4.3 billion passengers in 2018 and air traffic is forecast to double over the coming 15-20 years.

During the two-week conference, ICAO delegates will also touch on air safety, although two Boeing 737 MAX crashes that killed 346 people and led to the grounding of the fleet is not on the agenda.

On Monday, the US Federal Aviation Administration’s new chief, Steve Dickson, briefed his international counterparts on the FAA’s process for certifying the MAX to resume flights.

Dickson said the decision to resume flights will be up to each country, an acknowledgement of a lack of consensus among international regulators on the MAX.