**4. Smooth pathways for CO2 emissions to achieve the UN goal on climate change**

The consistency of future CO2 emissions with a prescribed UN target and their rapid reduction, as urged by the UN, are crucial in the elaboration of suitable pathways for the emissions. Prior to the modelling, however, two parameters need to be determined; an estimation of their level in the beginning of the mitigation and their expected cumulative amount during the mitigation (remaining CO2 budget).
