Sustainability Energy

‘Aggressive’ policies needed to curb airline emissions and meet Paris goals: report

“It’s exciting to see industry developing new technologies that can dramatically reduce aviation emissions. But to fully meet the ambitions of the Paris Agreement, either atmospheric carbon removals or curbs to traffic growth will be needed.”
Airplane flying through trees.
The Associated Press/Gene J. Puskar

Story at a glance

  • Air travel accounts for a significant portion of carbon dioxide emissions and serves as a main contributor to climate change. 

  • New advances in aviation such as zero-emission planes can help curb the industry’s negative environmental impact.

  • But to meet the ambitious targets laid out in the 2015 Paris climate treaty, immediate and aggressive action is needed, experts stressed.

One highly touted way of reducing one’s carbon footprint is to cut down on fossil fuel use in everyday life. For many Americans, this can mean finding transportation alternatives to air travel. 

In 2018, commercial aviation accounted for 2.4 percent of global carbon dioxide emissions, equalling approximately 918 million metric tons, according to the International Council on Clean Transportation (ICCT). 

For years governments have strived to meet ambitious targets laid out in the 2015 Paris Agreement aimed at keeping global temperatures from rising 2 degrees Celsius above pre-industrial levels and ideally reduce warming to 1.5 degrees celsius.

A new report from the ICCT found that to achieve the 2 degree Celsius goal, airline emissions must peak by 2030. However, aggressive policies must be implemented immediately to keep temperatures from rising above 1.75 degrees Celsius by the end of the decade, authors warned. 

“Cumulative targets, rather than an absolute emissions goal for a given year, would provide greater certainty that aviation contributes fairly to the Paris Agreement,” they explained. 

In the report, researchers laid out 3 scenarios to tackle decarbonization in the aviation sector. The Action, Transformation and Breakthrough scenarios vary in degrees of ambition and are built around six parameters: traffic, aircraft technology, operations, zero-emission planes (ZEPs), sustainable aviation fuels (SAF), and economic incentives. 

The roadmap laid out only includes international operations and compares each of the 3 scenarios to baseline emissions rates, or continuation of the status quo. 

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For the Action scenario, researchers assessed government and industry efforts to deliver new technology capping emissions below levels recorded in 2019 by 2050, authors explained. But this would still use up the industry’s carbon budget allotted for a 2 degree warming by 2050.

In comparison, the Transformation case shifts away from fossil fuels beginning in 2035 and halves 2050 levels compared with those recorded in 2005.

“In the Breakthrough case, early, aggressive, and sustained government intervention triggers widespread investments in zero-carbon aircraft and fuels, peaking fossil jet fuel use in 2025 and zeroing it out by 2050,” researchers said. This route would achieve a 1.75 degree temperature increase following the peak of emissions in 2025. 

Should one of these three scenarios be adopted, by 2050 emissions will fall by nine to 94 percent below 2019 levels. This will be achieved through uptake of SAF, introduction of ZEPs powered by liquid hydrogen, and overall improvements in aircraft and operational efficiency. 

The latter parameter would account for a one-third reduction in carbon dioxide emissions while ZEPs would lead to between 4 and 5 percent reductions. 

Transitions to SAF yielded the highest emissions reductions out of all the interventions modeled, as this effort could lead to a 59 to 64 percent decrease in carbon dioxide emissions. Currently, these alternatives only make up less than 0.1 percent of all jet fuel use. 

Additional models shifting mass transportation to high-speed rails in certain areas and reducing air transportation use based on increased fuel prices revealed more limited emission reductions. 

“It’s exciting to see industry developing new technologies that can dramatically reduce aviation emissions,” said co-author and ICCT aviation program director Dan Rutherford in a statement. “But to fully meet the ambitions of the Paris Agreement, either atmospheric carbon removals or curbs to traffic growth will be needed.”