It represents a simple, elegant solution to the challenge of reducing aggregate emissions from across broad sectors of our society. (ucsusa.org)
This instrument establishes a limit on aggregate emissions by specified sources, requires each source to hold permits equal to its actual emissions and allows permits to be traded among sources. (ipcc.ch)
That would limit the amount of GHGs per unit of output rather than putting a cap on aggregate emissions. (macleans.ca)