US rail company Amtrak has stepped up its efforts to attract green travellers with the launch yesterday of a carbon offsetting scheme.

The company announced it has teamed up with offset provider Carbonfund.org to offer customers the opportunity to offset emissions associated with their journey through the Carbonfund website.

All donations made through the initiative are tax deductible and passengers have the option to select from renewable energy, energy efficiency or forestry-based offset projects. Passengers are offered two options, allowing them to offset shorter journeys of less than 2,500 miles for $3.00 and offset longer journeys of up to 5,500 miles for $6.50.

The move is part of a wider initiative from the rail company to attract environmentally conscious travellers.

"By choosing to travel by rail, Amtrak passengers are already a step ahead because the carbon footprint generated by their trip is smaller than that of most other modes of transportation," said Roy Deitchman, vice president for environmental health and safety at Amtrak. "Because it is more energy efficient, travelling by rail contributes less per passenger mile to greenhouse gas emissions than either cars or airplanes. Rail travel also helps to reduce highway congestion in major urban centres."

According to Amtrak calculations rail travellers emit .21kg of carbon per passenger mile, compared to .35kg from cars and .48kg from air travel.