INFORMATION_SCHEMA.GLOBAL_VARIABLES alternative in 5.7? More info about show_compatibility_56

You need to enable the PERFORMANCE_SCHEMA.

See the documentation for details:

The Performance Schema is disabled by default. To enable it, start the server with the performance_schema variable enabled. For example, use these lines in your my.cnf file:

[mysqld] 
performance_schema=ON

*Please check updated syntax from mysql website

Migrating to Performance Schema System and Status Variable Table has all the information you'd ever need on the matter.