Your memory is foggy. He testified against it, but in his book Contract with the Earth, he goes into a scheme that mimics the Cap and Trade idea with a Conservative bent. One has trouble pinning down Newt on issues over the past couple years because he came down on both sides. He was going around with Rev Al a few years ago peddling education reforms. He ran around with Hitlery a few years ago peddling big govt' control of health records. You cannot slam Rick for being a RINO and with a straight face defend Newts Conservative purity.
Even when he testified against the particular democrat proposal, in that very testimony he said he would support cap and trade if it was limited to more polluted areas and combined with green coal and nuclear support.
Gingrich has said so many things that in most cases, you can find a quote where he supports the conservative position; so long as people don’t pretend that finding one conservative quote negates every non-conservative thing he said about the same subject.