WASHINGTON: Ad blocking is expected to reduce US display advertising by some $3.9bn this year, a figure that is forecast to treble over the next four years according to a new study, with a total of $39bn being lost over five years.

The Ad Blocking Survey and Forecast by analytics firm Optimal reported that 11.7% of ad impressions in the US were blocked in 2015, rising to 16.4% this year and 36.6% by 2020.

The great majority of blocked impressions (90%) currently happen on desktop, but Optimal said that blocking on mobile is sure to increase, not least as consumers find ads there "far more intrusive and annoying". Respondents in a survey of 1,712 smartphone users regarded mobile pop-ups, for example, as 3.7 times worse than TV ads.

And, the study added, the industry risks increasing the take-up of ad blocking software through a misguided focus on preventing ad blocking instead of tackling the underlying reasons 43m consumers turn to this solution.

As awareness of ad blockers rises – almost half (46%) of non-blockers didn't know they could block ads – so more people will start using them: the report forecast that 102m online Americans would be regularly deploying these by 2020.

Optimal has its own solution to the problem: it will charge users to view the web ad-free, or at least free of intrusive ads, and then split the revenue 70:30 with publishers, a model CEO Rob Leathern has described as a "shared subscription" service offering ethical ad blocking".

He told The Register that he saw an appetite, especially among younger users, to "pay for the ability to block ads while still supporting publishers".

The Optimal study offered ten recommendations, from enforcing standards to limiting volume. Leathern was particularly taken with one suggesting that 10% of ad space be devoted to feedback, according to Forbes.

This, he felt, would not only encourage consumers to notice ads more, it would provide hard data on whether and which ads are valuable or at least interesting. "This recommendation will pull the others along," he said.

Data sourced from Optimal, Forbes, The Register; additional content by Warc staff