EnergyFactbox: Global climate schemes putting a price on carbon emissions Susanna Twidale 1/2 Water vapour billows from smokestacks at the incineration plant of Ivry-sur-Seine, near Paris, France, December 18, 2019. REUTERS/Charles Platiau/File Photo Read More A World Bank report on Tuesday showed more than a fifth of the world's greenhouse gas emissions are now covered by a price on carbon dioxide (CO2) emissions to help meet climate goals. read more A carbon cost can come in the form of a tax or via an emissions trading (ETS), or cap-and-trade, scheme. An ETS sets a gradually decreasing cap on the emissions a sector, or group of sectors, can produce. It creates "carbon permits" for those emissions, which companies must buy for each tonne of CO2 they emit. Some sectors are given free permits to help maintain international competitiveness.