Greenhouse gas emissions of transport sector could double in two decades. Environment Minister Jairam Ramesh said, the transport sector accounts for 7.5 per cent of the greenhouse gas emissions in the country now. This is expected to be go up to 15 per cent in the next 15 to 20 years.Ramesh told a function in New Delhi that there has to be mandatory fuel efficiency standards to control the emissions. He said that a national transport policy committee has been constituted and the committee will give its recommendations in next 12 to 15 months.The Minister pitched for evolving an effective fuel policy regime to discourage the use of Sports utility vehicles that emit more carbons.