Forbes: As the climate change summit planned for December in Copenhagen draws nearer, grander and grander emission goals and reduction targets are floated in the press. Nevertheless, crucial details are mostly missing and will be fiercely debated given the nature of the problem at hand. Cap, trade and protect? Different policy instruments can be used to deal with climate change. Prominent among these are carbon taxes, direct regulation and a cap-and-trade system, whereby emission permits are …