The Clean Development Mechanism (CDM) allows developed countries to meet their emission reduction targets by paying for green house gas emission reduction in developing countries. CDM follows the goal of not only emissions reductions for industrialized countries, but also accelerated sustainable development in developing nations. It enables industrialized countries to efficiently and economically reach their targets. 

CDM projects generate Certified Emission Reductions (CERs). Each CER represents the abatement of one tonne of carbon dioxide equivalent. CERs are issued by the CDM Executive Board under the United Nations, after estimated abatement volumes have been validated independently, and a stringent verification process is in place for ongoing monitoring.

Joint Implementation (JI) follows the same concept as CDM, however the gas emission reduction projects are implemented in an industrialized country. JI projects generate Emission Reduction Units (ERUs).

Under Kyoto Protocol, both CERs and ERUs can be imported in the international Emission Trading schemes under certain constrains.