Starting from 2015/04/21 Google will now include how mobile friendly your website is when it suggests search results.
To many this won't be a problem but to others this will greatly reduce their SEO.
There's still a bit of time to improve your website before it happens. To test how mobile friendly your website is now Google has created a website tester.
You can find it here.
Starting April 21, we will be expanding our use of mobile-friendliness as a ranking signal. This change will affect mobile searches in all languages worldwide and will have a significant impact in our search results. Consequently, users will find it easier to get relevant, high quality search results that are optimized for their devices.