The strategy is to consistently and exclusively argue that not only is the issue still scientifically uncertain, BUT even if the science were sound (another frame device), any action that the U.S. might take to curb greenhouse gases is futile, since China and India are going to blow any such efforts away with their massive populations, economic growth, and pollution.
President Bush continues to employ a variant of these two frames. See his recent comments in reaction to the Supreme Court case on greenhouse gas emissions. He doesn't even mention "climate change" or "global warming," instead he says he takes greenhouse gases very seriously, "that man is contributing to greenhouse gases," but any action is futile unless China and India are on board. In part it's framing by avoiding any mention of connection to warming or any climate impact.