What are concentrations?
Concentrations differ from emissions in that they represent what remains in the atmosphere after some of the gases are absorbed by the seas, land and trees.
Since 1990 the warming impact of these long lived gases on the climate has increased by 41%.
How does the latest data compare to previous years?
2017 continues the rise in concentrations of CO2 which are now 46% greater than the levels in the atmosphere before the industrial revolution.
The increase from 2016 to 2017 was smaller than the rise from 2015 to 2016, but is close to the average growth rate seen over the last decade.