Capping Emissions is the Surest Way To Guarantee Emissions Reductions

Carbon trading provides the environmental certainty of a fixed cap on emissions. Other means of reducing emissions, such as carbon taxes, efficiency standards, and traditional command and control reductions, do not guarantee that total emissions stay below safe levels.  

There can certainly be a place for other measures as means to accomplish specific purposes beyond addressing climate change. For example, gasoline taxes fund highway improvements, efficiency standards help keep consumer energy bills lower, and command-and-control regulations can reduce smokestack emissions of other pollutants. However, none of these measures suffice to keep total emissions at or below safe levels. Carbon taxes allow companies and consumers to simply pay the taxes and keep emitting; efficiency standards reduce emissions per unit of GDP but do not guarantee an absolute reduction; and command-and-control regulations will reduce emissions from select industries, but do not guarantee that either consumers or other industries won't simply emit more emissions elsewhere.