What increases the amount of carbon dioxide in the atmosphere? Human activities are shown by atmospheric scientists to be responsible for increasing the amount of carbon dioxide CO 2 in the atmosphere. The major sources of human emissions are the burning of fossil fuels such as coal, oil and natural gas for industry, driving our transport, heating our homes and generating electricity. Humans produce between 3 and 6% of all carbon dioxide emissions. Natural carbon sources produce much larger quantities than mankind, but this is offset by the vast natural carbon sinks that remove CO 2 from the air. The current imbalance is due to human activity. We know where the increase comes from because CO 2 from fossil fuels has a specific chemical signature, and scientists have observed that the proportion of CO 2 from fossil fuels in the atmosphere has increased globally, and even more in cities and populated areas. Human emissions are not the only factor, but it is currently the most significant. For example, human emissions of CO 2 are more than 130 times greater than the amount released by volcanic eruptions. Burning wood or allowing trees to rot does not increase the amount of carbon dioxide in the atmosphere, as long as old trees are replaced by new ones which absorb as much carbon as the old ones had done. This is essentially part of the natural cycle, in which carbon is continually added to and removed from the atmosphere But deforestation does increase the