No . . .the browser it holding the cookie. :-) Environment variables are on the server, and an http_cookie envar is only present if the browser sends it to the server. Even if it's a persistent cookie, it still doesn't live on the server, it's in your browser (well, actually, stored in some file the browser uses.)
A thing about persistent cookies that it took me a long time to get right is the expiration date has to be in the correct format otherwise they won't "stick."