Four...top airlines have backed a global scheme to curb carbon emissions... It is the first time airline firms have banded together to make recommendations to U.N. climate change officials... Air France/KLM, British Airways, Cathay Pacific, Virgin Atlantic, airport operator BAA and international NGO The Climate Group have proposed a deal that covers all carbon pollution from the international aviation sector... Conservation groups such as WWF say aviation has not been doing enough to tackle the sector's growing share of greenhouse gas pollution...