Many scientists and policy makers are still trying to agree on the concentrations of carbon dioxide in the atmosphere that would avert the worst impacts of climate change on humanity. These typically range from 350 to 500 parts per million atmospheric concentration.
As of today, the concentration of carbon dioxide in the earth’s atmosphere is parts per million. It is increasing at parts per million per day.
Carbon emissions are part of a cycle balancing emission sources with carbon sinks – or storage. There are three principle organic carbon sinks: oceans, soils and forests.
Data from: Lal, R. (2008). Carbon sequestration.