As I previously mentioned, Modernizr used to be bundled with Respond.js, however recently as of version 2.5 it was decoupled from the library itself and must now be downloaded separately and then added manually. This was due to some IE 8 crashing issues.
Because it has been removed, I won't go into a lot of detail about it beyond implementing and lightly reviewing the example from the Respond JS download website and showing how to load it as a polyfill with
A fast & lightweight polyfill for min/max-width CSS3 Media Queries (for IE 6-8, and more).
This means if you wanted media queries regarding this scope to be backward compatible you could leverage ...