Our problem is that burning coal, oil, and gas produces carbon dioxide, which adds to the supply already in the atmosphere, increasing the greenhouse effect and thereby increasing the temperature of the Earth. Prior to the industrial age, the concentration of carbon dioxide in the atmosphere was less than (parts per million). This was determined from analysing air bubbles, trapped hundreds or thousands of years ago in the Antarctic and Greenland ice caps. By 1958 , the carbon dioxide concentration had risen to , and by 1986 it was 350 ppm.