Green house gasses were degrading our atmosphere until the oil industry said it wasn't.

“Bush administration officials agreed that greenhouse gases could endanger the public and should be regulated under clean-air laws, but later reversed course amid opposition from Vice President Dick Cheney’s office and the oil industry, a congressional report said. The “report is inaccurate to the point of being laughable,” said White House spokesman Tony Fratto.
Think Progress » ThinkFast: July 21, 2008