Carbon intensity is the annual mass of emitted CO₂ per unit of primary energy from the combination of all fuels. This is a measure of the carbonisation of an energy system; i.e. ‘how dirty it is’.
Decarbonisation of the world energy system has again stalled. From 1990 to 2000, decarbonisation was consistent but very gradual. This reversed over the next decade from 2001 to 2011, after which it again declined, but not until 2016 did carbon intensity return to the minimum value of year 2000. Over this 16 year period, from 2001 to 2016, humanity made no progress to decarbonise the world energy system. After 2016, decarbonisation continued until 2020; in 2021 carbon intensity matched that in 2020.
Carbon intensity in 2021 of regions and national economies is shown in red in the upper rows of the charts below. Changes since 1995, the year of the first United Nations Climate Change Conference of Parties (COP1)2 are shown in blue in the middle rows. Bottom rows show change of fossil fuel CO₂ emissions in 2020 (grey) and 2021 (black) relative to 1995.