Global Warming ?

I know that Global warming is happening because there are holes in the ozone layer and stuff but why is the wether changing so much and by that I mean this winter was actually rally "cold" ,is'nt it called Global "Warming" then why is it getting colder and what does that have to do with fluds and droughts and storms ,I mean should'nt Global warming only make our summer just hotter than usual ,why the heck is it making our winter colder and more miserable and why is it influencing storms and stuff.