Carbon Transportation

Google Flights: Carbon Tool Test Drive

Can carbon tools help fliers choose least emitting flights?

I’m planning for my first flight since 2019! Inspired by a recent post by Dan Rutherford, I thought I’d take Google Flights’ carbon impact tool for a test drive to research flight options.

Default search parameters for price and convenience return three options for Vancouver to London (one-way):

A one-click adjustment to sort by emissions returns the following:

Not surprisingly, the Air Transat flight with two layovers is high-emitting. What was unexpected was that the one-stop flight on Air Canada was lower-carbon than a non-stop option on Air Canada. And for the same price!

Another surprise: the 223 Kg difference in emissions between the WestJet and Air Canada itineraries, which both route through Calgary. The WestJet option is 23% higher emitting than the average YVR-LHR itinerary.

So what gives? The only apparent difference between the WestJet and Air Canada flights appears to be the aircraft used on the domestic leg to Calgary. WestJet lists a Boeing 737, while Air Canada lists a Boeing 737 MAX 8. WestJet’s website suggests they use the 737-800 and 900 as well as 737 Max aircraft on their routes, but the specific type isn’t noted in the fare returned by the Google tool. Different models have different fuel efficiency ratings, so that may contribute a difference, but without knowing the WestJet craft’s exact model I’m uncertain if it explains the margin. Would knowing the exact 737 model change the result?

(Google does note that speed and altitude of the aircraft and load factors also play a role in emissions estimates. And that they are continuing to improve their emissions calculator to increase accuracy. )

Anyone in my network have insight? Your input would help me decide if that +23% in emissions is a fair estimate, and if it really makes sense to pay the extra $100 and 15 minutes on the Air Canada fare to reduce emissions.

While I was hoping the tool would lead to fewer questions than it has, I still appreciate the ability to learn about and filter flights based on emissions. If nothing else it’s been a teachable moment that direct flights may not always be least emitting and that the fuel efficiency of the aircraft used matters a lot.

Have you used tools like Google Flights to reduce the carbon impact of flying? What have you learned?

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