Carbon market

♤ A popular (but misleading) term for a trading system through which countries may buy or sell units of greenhouse-gas emissions in an effort to meet their national limits on emissions, either under the Kyoto Protocol or under other agreements, such as that among member states of the European Union.

♤ The term comes from the fact that carbon dioxide is the predominant greenhouse gas, and other gases are measured in units called “carbon-dioxide equivalents.”