CO2: average of ppm on Earth

From 1832 to 2004, the atmospheric CO2 concentration increased from 284 ppmv* to 377 ppmv, or about 33%, with most of the change occurring since 1970. Burning fossil fuels such as coal and petroleum is the leading cause of increased man-made CO2; deforestation is the second major cause. - Wikipedia
Global warming, while not completely understood [...]