Google has been making great efforts lately to return more mobile-friendly sites in its mobile search results. Recently the search giant has even gone as far as to add a “mobile-friendly” tag to sites that pass Google’s criteria, so you know if a site will load on your mobile device before you even click on it.

Now the company is making a strong push for site owners to make the web a more mobile-friendly place. Owners of non-mobile friendly sites are receiving warnings via email that their site may be impacted by poor search visibility.

The email reads as follows:

Google systems have tested [X amount of] pages from your site and found that 100% of them have critical mobile usability errors. The errors on these [X amount of] pages severely affect how mobile users are able to experience your website. The pages will not be seen as mobile-friendly by Google Search, and will therefore be displayed and ranked appropriately for smartphone users.

What Google is not-so-subtly trying to say is that non-mobile friendly sites will be demoted in mobile search results. The email then goes on to encourage webmasters to fix the “problematic pages” by linking to resources about how to make your site more mobile friendly.

If you haven’t received one of these warnings but are concerned your site may not pass Google’s criteria, you can use its official mobile-friendly site testing tool.

Last month I wrote a prediction post about how SEO will change in 2015, and in it I predicted Google would flat out stop indexing non-mobile sites in its mobile search results. That’s not exactly what’s happening here, but it certainly looks like we’re seeing the first steps towards that becoming a reality.

I have to admit, even though I predicted something similar I didn’t expect to see it happening so early into the year. At least Google is giving site owners fair warning about their search visibility being affected, and I think it would be well advised for them to heed that warning.