"Social media apps may feel the burn, but traditional media will feel disintegrated," predicts Dustin York, a professor at Maryville University who follows media economics.

Perceptions of widely disliked standard in-game video ads have improved marginally, and the percentage who like rewarded video ads is actually slightly higher than the percentage who "can't stand" them.

There are more than 7.7 billion mobile phones on the planet, generating a footprint of more than 480 million tons of carbon each year. How much of that is spent using ad-supported media?

As long as smartphones have existed, so have concerns that the devices are revealing information about their owners' whereabouts.

Ten percent of them actually transmit their users' location in the advertising bid stream so they can be targeted programmatically by advertisers, more so for Apple iPhone than Android users.

About a third of Americans now use voice assistants for purchasing. Siri is the dominant assistant used on mobile.

Nestle has been testing mono sound and digitally compressed video on mobile, and found these factors made zero difference in performance, while reducing carbon 50%.

The German competition regulator Bundeskartellamt is investigating Apple over privacy settings that require developers to obtain users' consent before tracking them across mobile apps.