Gas-guzzling trucks and the cool summertime relief of air conditioners have helped make Texas the top source of greenhouse gases in the nation.

States like California and New York are moving quickly to address global warming.

The Associated Press reported the issue has prompted only scattered calls for reforms in Texas.

Republican Gov. Rick Perry has expressed doubt as to whether global warming is a manmade problem.

Figures show Texas spewed 670 million metric tons of carbon dioxide into the atmosphere in 2003. That's enough to rank Texas seventh in the world -- if it were its own country.

Details come from the U.S. Energy Information Administration.

Jim Henson is director of the Texas Politics Project at the University of Texas at Austin.

Henson said Texas political leaders read "environmental protection as government activism" and want no part of it.

But Perry spokeswoman, Allison Castle notes Texas is a heavily populated state.

She said Texas is the leading producer of energy, has the largest refining capacity and has the largest petrochemical industry in the nation.

Castle said it would be expected that Texas would have the largest total of greenhouse gases in the country.