International aviation produced more than 492 million tonnes of CO2 in 2014. Credit: Tyrone Turner/National Geographic Creative

A United Nations panel has proposed the first global greenhouse-gas emissions standard for aircraft.

The draft rule, released by the International Civil Aviation Organization (ICAO) on 8 February, applies to most commercial and business aircraft, including designs already in production. It would require minimal changes to aviation design over the next 12 years, and many environmentalists say that the proposal is inadequate to combat climate change.

The plan — which would take full effect in 2028 — could decrease fuel consumption by new aircraft at cruising speed by an average of 4% compared with the current level, according to the International Council on Clean Transportation (ICCT), a non-profit research group based in Washington DC. The ICAO is expected to adopt the CO2 standard later this year.

But many environmental groups found the UN panel’s action wanting. ”We think that this is just woefully insufficient,” says Vera Pardee, a lawyer with the Center for Biological Diversity in Oakland, California. She calls the requirements for new aircraft weak, and notes that the plan would not require any changes to aircraft that are already flying. “ICAO is not proposing to do anything about the existing fleet, and it could,” she says.

Daniel Rutherford, programme director for marine and aviation at the ICCT in San Francisco, California, agrees that the ICAO could have been much more aggressive. An ICCT study released last December found that manufacturers could reduce fuel consumption in new aircraft by 25% in 2024 and by 40% in 2034 in a cost-effective manner. These efficiency gains would come from improvements in engine technologies and aerodynamics, as well as reductions in aircraft weight.

Nonetheless, Rutherford says, the new ICAO standard is a step forward. “These standards do tend to matter over time as you update them and make them more stringent,” he adds.

Looking ahead

The ICAO process was designed to plug a gap in the UN climate agreement signed in Paris last December. That agreement did not address growing emissions from international aviation or shipping, which together account for more than 3% of humanity’s CO2 output. In addition to the CO2 standard, ICAO is working on a market-based offset mechanism that would levy a fee on international flights.

In the meantime, individual countries are free to implement more-stringent standards for aircraft emissions, and environmentalists are gearing up for a fight. For instance, lawsuits from environmental groups helped to push the US Environmental Protection Agency (EPA) to begin developing its own greenhouse-gas standards for aircraft.

Although the EPA has said that it is waiting to see what the ICAO’s final rule looks like, Pardee notes that the United States did push for a stricter standard when the UN panel met this week in Montreal. That could be a sign that the US agency will pursue regulations that are tougher than the ICAO plan. If it fails to do so, environmentalists could sue the agency once again. 

Meanwhile, the ICAO is also developing a market-based offset mechanism to cap international aviation emissions by raising money to reduce emissions in other sectors, beginning in 2021. The discussions build on the European Union’s decision in 2012 to include domestic aviation emissions in its Emissions Trading System. The EU plan initially included international flights, too, but officials backed off to give the ICAO time to develop its own offset scheme.

International aviation produced more than 492 million tonnes of CO2 in 2014, making its output larger than that of the United Kingdom. And that figure is projected to skyrocket in the coming years, with more than 56,000 new aircraft projected to hit the skies by 2040, according to the Environmental Defense Fund (EDF), an environmental group based in New York City. The EDF says that CO2 emissions from air travel and transport could triple or even quadruple over that period.

With that in mind, EDF lawyer Annie Petsonk argues that the ICAO’s proposed emissions standard sets an important precedent — and could create momentum for the panel’s nascent market-based emissions measure, which could achieve larger reductions in greenhouse-gas output.

“It’s going to be a tough negotiation, but the global spotlight is now on ICAO to deliver,” Petsonk says.