Since industrialization began in the 18th century, the concentration of carbon dioxide (CO2) in the Earth's atmosphere has increased significantly. Prior to the Industrial Revolution, the atmospheric CO2 concentration was relatively stable at around 280 parts per million (ppm). However, due to human activities such as the burning of fossil fuels, deforestation, and land-use changes, CO2 levels have risen dramatically.
the atmospheric CO2 concentration had reached approximately 415 ppm. This is an increase of over 47% compared to pre-industrial levels. It is important to note that this figure is subject to change as new data becomes available, and you may want to consult up-to-date sources or scientific organizations like the Intergovernmental Panel on Climate Change (IPCC) for the most recent information.