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What you need to know about Google Flights’ emissions whitewashing

Flight contrails.
Photo by William Hook on Unsplash

An update of Google’s methodology to calculate flight emissions has been met with backlash. Google has been accused of whitewashing the climate impact of flying by only taking into account carbon emissions and excluding contrails, but is it intentional or a lack of proper science and international standards?

A change in Google Flights’ emissions calculations now excludes all non-carbon related emissions and climate impacts.

Contrails account for two-thirds of the aviation’s industry climate impacts, and the move to no longer consider contrails severely underestimates the climate impacts of flying.

Google (NASDAQ:GOOG) claims to be committed to developing new methodologies with other online travel leaders to better assess and include the impact of contrails going forward.

With more and more consumers becoming increasingly aware of their carbon footprint, Google Flights has been including data on flight emissions next to the price and duration of the flight since September 2021.

The feature was added to help eco-conscious customers make flight decisions factoring in carbon emissions. The carbon emissions calculated are flight specific and seat-specific, taking into consideration the efficiency of an aircraft or which seating class a customer chooses. 

But the feature has recently been accused of whitewashing the full climate impact of flying with an update to the methodology used behind the emissions calculations.

New methodology only accounts for carbon emissions, ignoring other impacts

An update to Google’s Travel Impact Model (TIM) was released on open-source software site GitHub in July 2022, which now excludes all global warming factors except for carbon emissions.

Google cites “recent discussions with academic and industry partners” as the driver behind the decision to focus the TIM solely on carbon emissions. This removes non-carbon factors like contrails, which have been found to be just as bad for the climate as carbon emissions.

Contrails are the white wispy cloud-like trails left behind by aircraft that can be seen in the sky on a clear day. While they look innocent enough, contrails are actually creating a thermal blanket in the atmosphere that can speed up the effects of global warming. 

Similar to a naturally occurring cloud, contrails are formed when the hot exhaust gases of an aircraft come into contact with cold, low-pressure air when flying at high altitudes. The vapour of the exhaust condenses onto soot particles from the engine and quickly freezes into tiny crystals.

Climate effect of contrails

The contrails generally only last a few minutes, but as air travel continues to increase, the contrails can spread and merge together with other contrails and with cirrus clouds that can remain in the sky for up to eighteen hours. This can cause what some studies term as a “radiative force”, which disrupts the balance of radiation and heat emitted to earth from the sun, and from the earth back to space, causing a change in the climate.

The global effect of this contrail radiative force is expected to increase by a factor of 3 from 2006 to 2050, due to an increase in air traffic volume and a shift of air traffic towards higher altitudes.

Research published by the European Commission in 2020 found that overall, contrails are responsible for two-thirds of aviation’s climate impact.

The exclusion of contrails’ climate impact from Google Flight’s emissions calculator has therefore been seen by many groups as a way to conceal the overall impact of aviation on climate change. 

Transport & Environment, a European multi-stakeholder organisation promoting clean transport, tweeted that Google is “hiding the non-CO2 effects of flying… the company should show customers the true impact of each flight, as the European Parliament has proposed to do”.

Google argues that science isn’t there to back contrail impacts of specific flights

While Google agrees with the scientific consensus on the global impact of contrails, the company argues that the science has not caught up in regards to estimating contrail-related impacts on one specific flight. 

“We strongly believe that non-CO2 effects should be included in the model, but not at the expense of accuracy for individual flight estimates”, said a Google spokesperson. 

The previous version of Google’s TIM applied a global contrails factor to all emissions calculations, which resulted in emissions estimates for some flights being much lower or much higher than reality.

In the UK’s Department for Business, Energy, and Industry Strategy’s 2021 guidelines on calculating emissions for air transport, it is recommended that companies add a multiplier effect of 1.9 to account for the climate impact of contrails. However, the guidelines also acknowledge that this is a short term solution and the value of the multiplier “is subject to significant uncertainty”.

Working with academics on research

The uncertainty is because there are many factors that can determine the impact of contrails on climate including the time, region, altitude and meteorological conditions during the flights. 

Google argues that because the aim of their calculations is to help customers compare flight emissions on a relative basis, the inclusion of a global multiplier factor does not impact the relative comparison of emissions between different flights. 

The company claims that while they aim to calculate the accurate emissions number including contrails, there is a lack of available science that can include all the different factors to determine the contrails impact on a specific flight that can accurately represent impacts of different flights.

“To address this issue, we’re working closely with academics on soon-to-be-published research to better understand how the impact of contrails varies based on critical factors like time of day and region, which will in turn help us more accurately reflect that information to consumers”, explained a Google spokesperson.

There is a need to align methodologies on climate impacts of flying

While there are definitely reasons to be concerned about not accounting for contrails in emissions calculations because it downplays the overall impact of the aviation industry’s climate impacts, Google is not wrong that there currently is a lack of robust, widely accepted methodologies to calculate the specific impacts of contrails.

However, given that 92% of people begin their searches on Google, the choice to simply remove the contrails multiplier because it was not relatively useful to consumers could lead to the vast majority of people underestimating the climate impact of their flights.

Framework for estimating carbon emissions from air travel

Google is currently working with other leaders in online travel to align on methodologies through the Travalyst coalition, a non-profit founded by Prince Harry.

Along with Google, the coalition brings together Booking.com, Expedia Group (NASDAQ:EXPE), Skyscanner, Trip.com Group (NASDAQ:TCOM), Tripadvisor (NASDAQ:TRIP) and Visa (NYSE:V) to identify the changes that need to happen to make travel sustainable.

In April 2022, the initiative published a framework which included a set of shared principles and a preferred methodology for estimating carbon emissions from air travel. Skyscanner and Google were the first two members to implement Travalyst’s framework across their platforms.

Although the framework is an important step in the right direction to create transparency on flight emissions, it also does not take into consideration the impacts of contrails and other non-carbon related impacts.

It is clear that more research needs to be done to better assess and align on the full picture when it comes to the climate impact of flying. If Google follows through with its claims to deploy more robust methodology to account for contrails, this will be significant to accurately account for the aviation industry’s climate impact.

However, just because this methodology does not exist today, it still does not justify Google’s choice to remove the impact of contrails completely from its calculations as this misleads consumers to thinking the carbon footprint of their next flight is much smaller than it is in reality.

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