Dylan Smith wrote:

The evidence is conclusive that recent rises in CO2 concentrations (from
280ppm in 1900 to 320ppm now) are entirely caused by human activity. We
can see that CO2 levels have only varied between 270 and 290ppm for a
good 10,000 years prior to this point. Carbon dating the CO2 in the
atmosphere shows that the recent additions of CO2 (i.e. the change from
~280ppm to 320ppm) are from the burning of fossil fuels.

More likely, the increase is due to the decrease in forests which absorb
the CO2 and release oxygen in exchange. Still it can be traced back to
human activity, but not due to emissions...the decrease in the scrubbing
capacity due to deforestation is much greater than the small percentage
increase in emissions due to human activity. Same is likely true of
global warming.