Since July of this year, Google has changed the way it calculates the environmental impact of flights.
Previously the search engine had reported the carbon footprints of flights to include "carbon dioxide equivalent" measurements, which included elements such as contrails (water vapour cloud trails), known to trap heat in the atmosphere. Now, however, Google's calculations only include CO2 emissions, excluding these other contributing factors.
To put the impact of this into context, approximately 3.5% of global warming due to human activity is attributed to the aviation industry, but by only including CO2 emissions this figure reduces down to 2%.
In theory, comparatively speaking consumers may still get an idea of which flights are likely to be better or worse from an emissions perspective, but without including non-CO2 outputs experts agree that they only have "approximately half" of the picture. Businesses may find this particularly noteworthy where they are attempting to capture their carbon footprints (as part of their ESG initiatives or otherwise); finding that their reliance on Google's stats is suddenly impacting their figures in an unexpectedly positive way.
This is set against a backdrop of incoming EU legislation, requiring certain companies to have a climate transition action plan in place - ensuring that their business models and strategies are compatible with limiting global warming to 1.5°C (in line with the Paris Agreement), and which will inevitably impact on supply chain companies too. Companies will therefore want to know that what they're reporting or the data they're capturing is accurate and in line with current guidance.
A good place to start in the UK is the Department for Business, Energy & Industrial Strategy (BEIS)'s guidance. This sets out that non-CO2 impacts/emissions should be taken into account when reporting on greenhouse gas emissions, and their most recent table of conversion factors for calculating these impacts can be found here.
The Wider Angle
A final thought - a possible stretch in this case but still relevant to the huge power that Google's data and its portrayal (or lack thereof) wields on consumer and business habits at large. It's worth noting the broader question at play regarding Google's direct impact on competition and consumer choice, and indeed in the UK there is a CMA investigation ongoing (unrelated to this issue, I should add).
What's more, according to the BBC, Google's aviation carbon footprint methodology is "widely recognised as the industry standard". With such high impact industries relying on organisations like Google to hold them publicly accountable for their green ambitions, it seems the responsibility and importance placed on Big Tech to get this right is only ever increasing.
Yet in July, Google decided to exclude all the global warming impacts of flying except CO2.
Some experts say Google's calculations now represent just over half of the real impact on the climate of flights.
"It now significantly understates the global impact of aviation on the climate", says Professor David Lee of Manchester Metropolitan University, the author of the most comprehensive scientific assessment of the contribution of air travel to global warming.