Carbon dioxide (CO2) emissions from fossil fuel combustion were almost zero prior to 1750. The United Kingdom was the world’s first industrialized nation – and first fossil-fuel CO2 emitter.
In 1751 its (and global) emissions were less than 10 million tonnes – 3600 times less than global emissions today. We can conclude that emissions prior to 1750 were very low (and inconsequential to the numbers we compare today).
Annual CO₂ emissions, 1751
Carbon dioxide (CO₂) emissions from fossil fuels and industry. Land use change is not included.

Annual CO₂ emissions by world region
This measures fossil fuel and industry emissions. Land use change is not included.

Source: Our World in Data