If you search Google Flights to decide on a round trip from New York to London in mid-September and want to book the flight with the lowest negative impact on climate change, you can opt for a Virgin Atlantic trip, Air France-Delta-KLM, as its CO2 emissions are estimated to be 26% lower than typical for the route, while JetBlue flights could exceed the usual climate wallop by 14%.
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However, your choice could potentially be wrong from a climate change perspective, as earlier this summer Google stopped including the impact of Contrails — those trails of ice clouds behind the plane that trap heat but have looking pretty as the jets disappear from view across the sky. Scientists say the negative environmental impact and global warming effects of contrails can be just as important, if not more so, than CO2 emissions.
Google eliminated contrail data from its emissions calculations after speaking to academics who advised that the science of measuring the impact of contrails from specific flights is not accurate. And the negative impact of contrails can vary greatly depending on whether it’s a day or night flight, and other factors.
Google had previously multiplied CO2 emissions by a single number for all flights to account for non-CO2 emissions.
This could skew the real-world analysis of one specific flight versus another, so Google opted to simply use CO2 impacts in its Google Flights calculations as a stopgap measure. He intends to add contrail data to the mix when he is comfortable the data is accurate.
“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. “To address this issue, we are working closely with leading academics on soon-to-be-published research to better understand how the impact of contrails varies with critical factors such as time of day. and region, which will help us to more accurately reflect this information for consumers. »
But Google’s elimination of contrail data – Skyscanner doesn’t include it either – has led to controversy.
The BBC recently published an article with the headline, Google is ‘eliminating’ stealing shows, BBC reveals. The story inferred that Google bowed to pressure from partner airlines to make them appear more eco-friendly.
The BBC article quoted a Greenpeace scientist as saying: “Google has erased much of the aviation industry’s climate impacts from its pages. »
John Fleming, a senior scientist at the Institute for Climate Law, Center for Biological Diversity, said Google underestimated the impact of aviation on climate because it removed factors other than CO2.
“To completely eliminate the effect of factors other than CO2 doesn’t seem to enhance accuracy,” Fleming said. Moreover, in their modeling, they keep the labeling ‘CO2e’, which implies taking into account the CO2 and non-CO2 factors, which is misleading since they no longer do so. On the contrary, it would have been better to leave the non-CO2 data and modify it as it acquired more information on the stakeholders or more precise data, rather than to delete it completely.
Google seems to take some of these types of reviews into account. Google is developing a Travel Impact Model on GitHub to measure and share learnings with interested parties. Google has confirmed to Skift that it has removed the “CO2e” label from the model’s documentation and is now replacing “emissions” with a more generic label.
However, on Google Flights, travelers see the impact labeled as “303 kg of CO2, -19% emissions”, for example, which means that the estimated 303 kg of CO2 used for a particular flight is 19% less. pollutants than for the typical flight on this route. However, similar to the Travel Impact model, Google Flights no longer includes impacts other than CO2, such as contrails.
Google Flights allows travelers, if they choose, to search for flights based on environmental impact, and it will also list train options, if there are any on that route.
Asked about Google’s decision to temporarily remove contrail data from its airline emissions calculations, Marc Stettler, a PhD in engineering and senior lecturer at Imperial College London, quoted a BBC interview he did on the subject.
In the interview, Stettler agreed with Google that drag data, while having a huge impact when it comes to global warming, is not accurately measured at this point for specific flights, because there are so many variables. , such as the atmospheric conditions during the flight.
“We know that an average value that was previously included in the calculator is not accurate and there are better ways to find more accurate estimates,” Stettler said. “I am interacting with Google to improve these estimates. I don’t speak on their behalf, but I trust that it will be restored at some point. »
Flight search engine Skyscanner, like Google, does not include drag data in its carbon emissions calculations.
“Our Greener Choice label highlights flights that contribute a minimum of 6% less than the average emissions for a particular route,” a Skyscanner spokesperson said. “It’s about making it easy for travelers to relax and compare the impact of their preferred flight to make an informed choice near the point of purchase. »