The development of CO² emissions over the coming decades will substantially influence the climate development and its effects on earth. These developments will amongst others determine the scale of global warming, sea rise level increases, hunger effect developments and wild species extinction. 

The Intergovernmental Panel on Climate Change (IPCC) has modelled various CO² emission pathways, leading to different temperature rise scenarios. 

Source: https://www.ipcc.ch/sr15/chapter/chapter-2/

To keep global warming below 2.0°C, the world will need to reach a “Net-Zero-Emissions-Target” by 2050. This means, that all emissions emitted by mankind from the year 2050 onwards, will need to be offset through carbon capturing projects (i.e. afforestation).