How to convert Mysql encoding utf8 to utf8mb4 in Rails project

I have a Rails 3.2 project using Mysql 5.5.34, with utf8 encoding. Now I found that with utf8 encoding Mysql could not save unicode characters which represent emoji.

So is it OK for me to convert the whole database to use utf8mb4 encoding that I found on the web that could hold 4 byte unicode include emoji?

Is all the information I have in the database covered by utf8mb4 encoding? Will I face data loses if I do that?

Is there any way that Rails provide to do that?

Thanks a lot for helping.