This post is from ScIU’s archives. It was originally published by Adrienne Keller in March 2018 and has been lightly edited to reflect current events.
Carbon dioxide (CO2) concentrations in our atmosphere continue to rise, and global warming has transitioned from a possible future phenomenon to a present environmental reality. Given this reality, scientists are motivated to improve calculations of how much carbon there is on Earth and how it flows from the biosphere to the atmosphere and back to the biosphere. This understanding of how carbon moves through our Earth system will help scientists develop better strategies to mitigate the effects of global warming on our natural and built environments.
On land, much of the carbon in soils originates from plants. Recall that during photosynthesis, plants take in CO2 from the atmosphere and convert this carbon into sugars to enhance plant growth (an example of a carbon flux from the atmosphere to the biosphere). Then, when these plant tissues die and begin to decompose, the carbon again moves from one pool to another. Some of the carbon will be released back to the atmosphere, but about half of the carbon from the decomposing plant will get incorporated into the soil. This movement of carbon from the atmosphere, to the biosphere and then eventually to the pedosphere (the soil) is fundamental to the global carbon cycle. To understand this cycle, we must be able to estimate how large the plant carbon pool is.