Was Google right to ‘airbrush’ flight emissions data?

CO2 readings are given for all journeys booked on Google Flights, so green-minded organisations and individuals can choose the most environmentally-friendly option. But as numbers plummet, questions are being asked. 

Data showing carbon dioxide (CO2) emissions from trips booked through Google Flights has been halved, and therefore offers a misleading picture of the real-terms climate impact of any given trip. 

The BBC was first to report news Google Flights emissions readings had plummeted by around 50%, the change resulting from a decision in July to report only CO2 emitted on each journey. In the past, emissions data included kilograms of ‘carbon dioxide equivalent’ (CO2e), which also takes into account other damaging emissions, for example water vapour in contrails that actually have a significantly stronger warming effect than CO2 at high altitude.  

According to Google, difficulty in modelling the exact amount of CO2e for each trip – which varies depending on time of day and location – means old readings were not accurate, and it has instead opted to offer data on what can be measured: direct CO2. However, questions are being asked as to why this significant change was pushed through without a public statement, and whether or not the tech giant has made the right decision given the urgent need to raise awareness about the relationship between global warming and travel. 

‘We strongly believe that non-CO₂ effects should be included in the model, but not at the expense of accuracy for individual flight estimates. To address this issue, we’re working closely with leading 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,’ read a statement from Google, issued after the new data decision made headlines. 

In 2019, researchers at the Massachusetts Institute of Technology (MIT) published a study that suggested aviation emissions impact air quality more than the climate.