ABSTRACT
Carbon dioxide emissions have grown less fast than the economy because of improvements in energy efficiency. Switching to less carbon-intensive fuels and climate policy have played a minor role. Scenarios of future emissions are optimistic about economic growth and energy efficiency, and the higher scenarios assume resurgent coal use at odds with current trends. Climate policy is cheap for moderate targets and smart implementation. Costs are much higher for more realistic policies and for more stringent targets. The negative emissions required by the Paris Agreement would need large subsidies. Greenhouse gas emission reduction is a global public good that is hard to provide. Key players in the climate debate benefit from the rents created by inefficient policies, from causing confusion, and from mixing climate with other matters.
