It was in 1896 when S. Arrhenius first noticed the potential effect of humanactivities on the carbon cycle and the implications for climate change. He put forward thetheory that CO2 in the atmosphere was an important greenhouse gas and that it was a byproductof burning fossil fuels. In 1958, Charles Keeling began the observations at MaunaLoa Observatory, 3650 m up a mountain in Hawaii, regarded as far enough away from anycarbon dioxide source to be a reliable measuring point. Measurements of CO2 in theatmosphere have been continuous for almost 50 years. In recent decades, CO2 increased onaverage by 1.4 parts per million (ppm) a year because of the amount of fossil fuels burnt.
