The United States insisted Wednesday it was taking steps to tackle rising temperatures and that many of its actions to promote energy efficiency and switch to cleaner technologies were going unnoticed by the rest of the world.

U.S. delegates on the sidelines of a U.N. conference on climate change said America had spent more than any other country -- $37 billion -- since 2001 on climate change-combating activities

Since the conference began last week, the United States has been on the defensive over its refusal to accept emissions reduction targets of 25 percent to 40 percent.

"What the United States desperately needs to do at these talks is make it very clear that we are ready to accept responsibility for our historic and current emissions and then help the rest of the world to the next round of binding commitments."

"I get a little confused when I hear the United States isn't doing much. There is an enormous amount going on in the United States," Karsner said.