In a New York Times op-ed piece (December 6, 2009), climate scientist Jim Hansen makes the following argument: “Consider the perverse effect cap and trade has on altruistic actions. Say you decide to buy a small, high-efficiency car. That reduces your emissions, but not your country’s. Instead it allows somebody else to buy a bigger SUV – because the total emissions are set by the cap.” He argues that this renders a cap-and-trade system ineffective. Why is this argument wrong?