Answer:
worldwide burning of fossil fuels
Explanation:
The heavy usage of the fossil fuels as energy sources for the industry has resulted in much increased emissions of CO2 in the atmosphere. It all started around 200 years ago with the Industrial Revolution. In order for the machines to function, efficient energy sources were needed, and the best thing at that time for that was the coal. Through the burning, the coal manages to release enormous amounts of CO2 into the atmosphere. After some time, the oil was discovered as well, and it started to be heavily used as well, further increasing the CO2 emissions. As the technology has been developing more and more, the demand for the usage of the fossil fuels has been increasing constantly, so there's an ever growing CO2 emissions into the atmosphere.
