In this week’s viewer question, a viewer asked: how does the carbon cycle work, and and how much carbon dioxide can the Earth absorb? Every year, natural systems take in enormous amounts of CO2, but that balance is changing. Carbon moves constantly between the atmosphere, living organisms, the soil, and the oceans. Plants absorb CO2 through photosynthesis, while soils and oceans store large amounts of carbon. Scientists call these natural storage systems carbon sinks. At the same time, carbon is released through breathing, combustion, and natural processes like volcanic activity. But as ecosystems are damaged and temperatures rise, these sinks are reaching their limits, pushing the carbon cycle out of balance.