Google Flights removes contrails from the carbon calculator

Google has changed the way it calculates the climate impact of air travel in a way that dramatically underestimates key factors in aviation’s contribution to climate change.


BBC reports revealed that the company began excluding all global warming impacts from the flight in addition to carbon dioxide from its climate calculator from July.

This may not seem like a big change, but as a result the estimates of carbon emissions per passenger are now considerably lower than they were before the change. Indeed, carbon dioxide emissions and effects such as drag formation contribute more than half of the actual climate impact of flight. Google itself acknowledged the problem when it quietly announced the change on GitHub last month, saying that “factors other than carbon dioxide are critical to include in the model, given the emphasis on them. in the latest report of the Intergovernmental Panel on Climate Change.

“Google has erased a lot of the aviation industry’s climate impacts from its pages,” Greenpeace chief scientist Doug Parr told the BBC.

Contrails are trails of ice crystals that form in the wake of an aircraft. They also contribute enormously to the climate impact of flight and are responsible for more than half of the climate impact of flights and up to 2% of total global warming. That’s a big number, and one that academics and some in the aviation industry are working to reduce.

Being able to accurately estimate and predict the climate impact of contrails remains a challenging task given that the time of day, temperature and altitude of a flight can all play a role in the severity. impact. Yet Google chose to exclude the factor entirely from its flight emissions calculator.

Public knowledge of the climate impact of contrails is already low. But Google’s new changes to its flight computer put them even further out of sight, out of mind. The scope of the calculator extends beyond Google pages; the BBC notes that it is used by Skyscanner, Expedia and other major travel sites.

The decision to remove contrails from Google’s calculations is particularly concerning for the climate because, unlike reducing carbon dioxide emissions, reducing contrails and their impact on global warming could have immediate benefits. Indeed, while carbon dioxide stays in the atmosphere for centuries, the impact of warming contrails is fairly short-term. Reducing them would reduce short-term climate damage, even as the aviation industry strives to reduce long-term carbon emissions.

Sources close to the company’s work told Protocol in April that Google was working with industry experts to better incorporate contrails into its carbon calculator. As recently as last October, the page reported that Google Flight’s emissions estimates included both carbon dioxide emissions and non-carbon dioxide effects, including contrails, using estimates based on “lower bounds derived from scientific research”, citing a 2018 Nature paper.

Any mention of streaks has since been removed from the page. In last month’s GitHub announcement, Google said it was working with researchers and other partners to improve modeling of factors other than carbon dioxide, and that it would “share updates at an later date”.

“We strongly believe that effects other than CO2 should be included in the model, but not at the expense of the accuracy of individual flight estimates,” a Google spokesperson said in an email noting that the company was working “on future projects”. published research” on the subject.

Update: A Google comment was added to this story on August 25, 2022.

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