Plunging US Dollar is why.
All GCC currencies for some reason (I think it has to do with keeping the yanks happy about Oil prices) are fixed to the not so mighty Greenback.
Carrefour and probably most other chains import most of their goodies from Europe (Inc UK) and Non USD countries.
Dollar goes down 15%, prices go up 20% (what!!!)

If it makes you feel any better - It's happening all over the GCC.