Cirium Flight Emissions Review
Transparent airline rankings report
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What’s included in the Cirium Flight Emissions Review:
Global and regional rankings show the top carriers by ASK in each market, ranked by CO₂ per ASK. These cover the global top 20, the ten largest airlines by total capacity, and intra-regional performance across North America, Western Europe, Southeast Asia and Latin America. Inter-regional rankings cover the transatlantic and transpacific.
Route-level analysis identifies individual airport pairs where CO₂ per ASK improved most year on year, broken down by long-haul, medium-haul and short-haul segments. Each route table includes the equipment change that drove the improvement.
Year-on-year change is shown alongside current performance throughout the report, so that readers can see both where an airline stands today and whether it is improving.
Measure the carbon emissions from a flight, aircraft or seat with unmatched accuracy.
“EmeraldSky is Cirium’s emissions intelligence framework. It applies a single, consistent methodology across the global airline industry so that carriers can be compared directly, regardless of their size, business model or geography.”
Jeremy Bowen
CEO, Cirium
Building Confidence in Emissions Data
Independent, verified and trusted flight emissions data to aviation stakeholders.
EmeraldSky, the most accurate methodology for fuel burn and CO2 emissions, audited by EY and accredited by the Rocky Mountain Institute (RMI) as a qualified data provider to the Pegasus Guidelines. EmeraldSky achieves an independently calculated unrivalled >99% accuracy on emissions. Collaborate with Cirium, a leading data member of Impact on Sustainable Aviation.
The Importance of ISAE 3000 Assurance
Accurately measuring aviation’s carbon footprint is a complex challenge—but it’s also essential. That’s why Cirium sought independent validation of its EmeraldSky Flight Emissions methodology. The recent achievement of ISAE 3000 Reasonable Assurance, following a detailed review by PricewaterhouseCoopers LLP (PwC), is an important step in helping the industry rely on data it can trust.
ISAE 3000 is a globally recognized standard for assurance of non-financial information. Achieving Reasonable Assurance—the highest level available—means that EmeraldSky’s methodology, internal controls, and data processes have been thoroughly assessed and found to meet the standard’s rigorous requirements. For those using the data, it brings greater confidence in how emissions are modeled and reported.
The Cirium Flight Emissions Review 2025 is here!
Explore the latest operational insights and actionable intelligence helping aviation stakeholders drive efficiency and sustainability progress.
Build smarter, more sustainable travel programs and benchmark flight emissions with EmeraldSky.
EMISSIONS DATA OVERVIEW:
A one-page guide to the data points considered in Cirium emissions calculations.
EmeraldSky Methodology:
See our unique data-driven approach to emissions calculations.
EmeraldSky Comparisons:
Take a look at how we stack up to other solutions in the market.