Delta Air Lines has become the latest aviation setting set its sites on becoming 'carbon neutral', setting a target date of 2030 and pleding to invest $1bn in achieving the goal over the next ten years.

Investment will focus on on driving innovation, advancing clean air travel technologies, accelerating reductions in waste and emissions, and establishing new offsetting and natural carbon sequestration projects, the firm said.

"As we connect customers around the globe, it is our responsibility to deliver on our promise to bring people together and ensure the utmost care for our environment," said Ed Bastian, Delta's CEO. "The time is now to accelerate our investments and establish an ambitious commitment that the entire Delta team will deliver."

The commitment follows those of British Airways owner IAG, Quantas and Etihad, which have all separately pledged to reach net zero emissions by 2050 - two decades later than Delta - through a combination of new technologies, fuel efficiency and offsets. Last month the UK aviation sector published its own roadmap to achieving net zero by 2050, although the plan incurred criticism from green groups as a "flight of fancy". 

The aviation industry accounts for roughly two per cent of global carbon dioxide emissions. A recent study from the International Council on Clean Transportation found that the industry's emissions are rising 70 per cent more rapidly than predicted by the UN, and are set to triple by 2050 unless action is taken.

Delta's carbon footprint is its largest environmental impact, with 98 per cent of emissions coming from its aircraft, according to the firm. Progress towards its new goal will involve investment in industry-wide efforts to decrease the use of jet fuel and increase efficiency, through a fleet renewal programme, improved flight operations, weight reduction, and development and use of sustainable aviation fuels, the firm said.

It will also involve supporting offsetting and natural carbon sequestration projects, with Delta pointing to investments in forestry, wetland restoration, and grassland conservation.

"There's no challenge we face that is in greater need of innovation than environmental sustainability, and we know there is no single solution," Bastian added. "We are digging deep into the issues, examining every corner of our business, engaging experts, building coalitions, fostering partnerships and driving innovation."

Delta's past sustainability efforts have included adding more than 80 new aircraft in 2019 which it said were 25 per cent more fuel efficient than its previous aircract, as well as partnering with Northwest Advance Bio-Fuels to drive the development of more sustainable aviation fuel.

However, campaigners warn that such voluntary measures will need to be backed by robust industry-wide rules if the aviation industry is to be reshaped to fit a climate-friendly economy. At the start of next month, the UN International Civil Aviation Organisation (ICAO) Council will meet to decide which carbon offset programmes airlines can use under CORSIA, its carbon offsetting and reduction program for the aviation sector, which caps the net carbon dioxide emissions of most international flights at 2020 levels.

In advance of the meeting, a coalition of NGOs led by the Environmental Defense Fund (EDF) and the International Coalition for Sustainable Aviation wrote an open letter on Friday to ICAO warning it of a "substantial backlash" if it fails to agree meaningful rules to limit emissions.

"Your decisions could show your commitment to stand up CORSIA with integrity so that it supports emission reductions projects and low-carbon economic development," the letter states. "But if you end up putting out the welcome mat for bad quality, double-counted emissions units, you will destroy CORSIA's potential effectiveness, compromise the credibility of ICAO and the world's airlines, and make global climate change worse."

The letter urges ICAO members to bar older and less robust carbon credits, ensure carbon credits aren't double counted, and to make ICAO's decision processes transparent.

Signatories to the letter include Anne Petsonk, the international counsel for the Environmental Defense Fund, who warned if the negotiations fail to meet such basic standards, "our ability to tackle climate change will have taken a backward step."

"If CORSIA is peppered with bad quality, double-counted emissions units, its effectiveness will be fundamentally weakened, as will the credibility of the UN's ICAO Council and the world's airlines," she said.

In response to the letter, ICAO said its targets under CORSIA "represent the consensus of the 193 national governments".

"We encourage any advocates wishing to influence ICAO outcomes to learn more about how the world functions at the multilateral level, and to consider that it might be more effective to tailor and direct their calls and campaigns toward the actual decision makers involved in the issues they are concerned with."