(Bloomberg) -- Etihad Airways can no longer run two recent advertisements in the UK after a regulator found their environmental claims were “exaggerated.”

The ads, promoted on Facebook in October last year, suggest the Abu Dhabi-based airline is “taking a louder, bolder approach to sustainable aviation,” but failed to back up the claim, the Advertising Standards Authority found in a ruling published on Wednesday. 

“The claim exaggerated the impact that flying with Etihad would have on the environment,” the ASA said. “We understood that there were currently no initiatives or commercially viable technologies in operation within the aviation industry which would adequately substantiate an absolute green claim such as ‘sustainable aviation,’ as we considered consumers would interpret it in this context.”

The ruling, which bars the airline from showing the advertisements in their current form again in the UK, is part of a series of investigations by the regulator into marketing campaigns promoting a company's climate action. The ASA and other European regulators are cracking down on “greenwashing” to protect consumers from unreliable claims of environmental sustainability.

Etihad Airways said it’s disappointed by ASA’s decision. “Sustainability is a key priority for Etihad,” the company said in an e-mailed statement, highlighting its investments in fuel-efficient aircraft, sustainable aviation fuels research, as well as carbon offsetting and reforestation through mangroves.

In a similar case in March, German airline Lufthansa was banned from using an advertisement that claimed it was “Connecting the world. Protecting its future,” after the ASA said no current technology enabled an airline to claim it was protecting the world’s future. Irish airline Ryanair and Austrian Airlines are among other companies to have had advertisements banned by European regulators.

Also in March, environmental activists reported Etihad to the Australian Competition and Consumer Commission, a watchdog, over advertisements during a sports game that promoted its ambition to reach net zero emissions by 2050 with the tagline “Flying shouldn’t cost the earth.” The airline has no credible path to net zero emissions by its deadline, the activists argued.

Aviation causes a relatively small proportion of global emissions — around 2% — but this is expected to rise as other sectors progress more quickly toward decarbonization and passenger numbers increase. 

It is a particularly difficult sector to decarbonize. Alternative sources of power such as hydrogen and electricity are far from being commercially viable, and biofuels made from crops, an alternative to fossil fuel, compete for land with agriculture for food production, and may not be carbon neutral.

The Dutch airline KLM is expected to appear in court on April 20 in a case brought by environmental groups over its adverts. The company says it allows customers to lessen the impact of flying by buying offsets which fund projects such as reforestation and biofuels. The credits are widely used in aviation, but have been criticized as being difficult to validate and measure. The ads give “the false impression that its flights won’t worsen the climate emergency,” according to Fossielvrij, one of the groups bringing the case.

--With assistance from April Roach.

(Updates with information about KLM legal case in last two paragraphs.)

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