General Motors is accused of being "Global Warmer Number One" by a US pressure group called Environmental Defence which has produced a report calculating the carbon dioxide (CO2) produced by the new vehicles sold each year by major vehicle manufacturers. Environmental Defence, which describes itself as a "leading" New York-based national nonprofit organisation representing more than 300,000 members, claims that General Motors' fleet imposes the largest "carbon burden", producing 6.7 million metric tons per year.