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How Do You Calculate the Carbon Footprint of Flying?


By now, we’re all familiar with the idea that our lives, from the food we eat to the cars we drive, have carbon footprints. Flying comes under special scrutiny both because jets pump carbon directly into the upper atmosphere and because it is often volitional — we fly for business instead of teleconferencing and jet to Cabo for an all-inclusive vacation instead of going camping.

But measuring carbon emissions from airplanes is tricky and results can vary widely. The U.N.’s International Civil Aviation Organization (ICAO) set out to end disputes over aviation emissions in 2008 by introducing one carbon calculator to rule them all, complete with a section on methodology (pdf). Not that it settled anything. One prominent critic noted that the ICAO calculator doesn’t allow flyers to select the aircraft they’ll be flying on or indicate whether the flight is full or empty. “In general,” a contributing editor to Consumer Reports noted, “the more information a calculator requests about your trip, the better.”

It may not matter a whole lot if you are responsible for 804 pounds of carbon dioxide on a one-way flight from Los Angeles to Newark, as ICAO claims, or almost 1,200 pounds, as ClimateCare does, or 644 pounds, as TerraPass suggests. But if the European Union starts making airlines pay for their carbon emissions, which it has announced plans to do in 2012, passengers might start to matter how their contribution is calculated. Especially if airlines start charging for it. So we decided to take a peak underneath the hood of ICAO’s methodology. Here’s what we found:

Carbon footprints of some popular domestic and international routes according to calculators from ICAO, TerraPass (which requires users to choose their airline) and ClimateCare:

New York Laguardia (LGA) – Chicago O’Hare (ORD)

ICAO: 280 pounds of CO2

TerraPass (on American Airlines): 316 pounds of CO2

ClimateCare: 308 pounds of CO2

New York Kennedy (JFK) – London Heathrow (LHR)

ICAO: 849 pounds of CO2

TerraPass (on Delta): 979 pounds of CO2

ClimateCare: 1,700 pounds of CO2

Los Angeles (LAX) – San Francisco (SFO)

ICAO: 163 pounds of CO2

TerraPass (on United): 166 pounds of CO2

ClimateCare: 154 pounds of CO2

Hong Kong (HKG) – Taipei (TPE)

ICAO: 218 pounds of CO2

TerraPass (on Cathay Pacific): 188 pounds of CO2

ClimateCare: 220 pounds of CO2

Sydney (SYD) – Los Angeles (LAX)

ICAO: 2,064 pounds of CO2

TerraPass (on Cathay Pacific): 2,100 pounds of CO2

ClimateCare: 4,034 pounds of CO2