|Acres of restored plant communities, like this area inside the Main Ring, can store tons of carbon. Photo: Fermilab|
Tracking carbon dioxide, or CO2, in the atmosphere has been a compelling job for scientists around the globe for the last 50 years. Since the Pliocene era, roughly 800,000 years ago, the CO2 concentration in the atmosphere has remained relatively stable, cycling between 200 and 300 parts per million. However, since the late 18th century, CO2 levels have risen sharply. In early May of this year, NOAA scientists at their observatory in Mauna Loa, Hawaii, recorded a CO2 concentration of over 400 ppm for the first time in modern history. The increase in CO2 since the industrial revolution is largely due to human activities such as burning fossil fuels and mining carbonate rock. The increase is troubling because of the role CO2 plays in global climate change.
CO2 in the air cycles on an annual basis, rising during the winter months and declining during the summer because green plants are able to capture CO2 from the air and sequester it in plant tissue. During the growing season, green plants can store nearly half of the CO2 available in the atmosphere. While the 400-ppm level was a one-day measurement that will predictably decrease over the summer, it is just as predictable that next May’s concentration will be even higher, as the annual CO2 level continues to rise.
Plants are able to sequester carbon through photosynthesis, which converts CO2 from the air into materials (such as leaves and wood) that plants need to survive. When plants die and decay, some of the carbon is released back into the atmosphere as CO2, but not all of it. The “standing army” of forests holds millions of tons of carbon, bound up in woody tissue, and prairies transport carbon into their root structure, where a portion is subsequently transferred to the surrounding soil. Fungi associated with tree roots also store large amounts of carbon gathered from plants. On average, forests are can store up to 4 metric tons of carbon per acre per year, and prairies can store roughly 1 metric ton per acre per year.
Fermilab’s green plants, mostly in forests and restored prairie tracts, are capable of sequestering thousands of tons of carbon on a temporary basis each year. So in addition to preserving biodiversity, beauty and recreational opportunities, there is one more service that our natural areas provide for us!