Carbon is one of the most important elements found on Earth. The carbon cycle supports all life by transferring carbon between living things and the environment. Plants take up carbon dioxide (CO2) and release oxygen (O2) during photosynthesis, which transfers carbon to their stems, roots, and leaves as they grow. When leaves fall and decompose or when plants die, the carbon that was stored in plants is released through respiration or combustion and transferred back to the atmosphere or to the soil. Because of these processes, forests and other natural ecosystems can store considerable amounts of carbon and act as an important global carbon sink.
Issues
The amount of carbon stored in the Earth’s atmosphere is miniscule compared to the amount stored in oceans, soils, and geologic formations. Small additions to the atmosphere over a long time have an enormous effect on the global carbon cycle. The start of the industrial revolution nearly 300 years ago, marked the beginning of the period during which human (anthropogenic) activities moved large amounts of carbon from different terrestrial and geologic stocks to the atmosphere. Emissions from fossil fuel use and land use change have been increasing over the last three centuries and currently result in a net addition of approximately 9 GtC per year to the atmosphere. These anthropogenic fluxes have led to a 19-36% shift of carbon out of the Earth’s gas, oil, and coal reservoirs, carbon that had been essentially locked away from the carbon cycle for millions of years but is now expected to remain in the atmosphere for decades to centuries. This contribution of fossil fuel carbon to the atmosphere can be considered a net addition to the contemporary carbon cycle and a driver of climate change.
Management Options
It is increasingly important to consider the current and long-term effects from climate change, where land management seeks to maintain or increase carbon stocks or to provide a source of renewable energy. Adaptation actions, which work to reduce a system’s vulnerability to a changing climate, can help support beneficial carbon outcomes. Adaptation and mitigation are not alternatives to one another, but rather are part of an overall strategy to lessen the severity of climate change impacts. For example, increasing soil organic matter enhances soil carbon while also improving the water-holding capacity of soil and reducing the vulnerability of forests to more frequent intense drought. Management actions that serve to adapt forests and grasslands to changes in climate are critical for maintaining existing carbon pools and reducing losses of ecosystem carbon to the atmosphere.
Kayler, Z.; Janowiak, M.; Swanston, C. 2017. Global Carbon. (June, 2017). U.S. Department of Agriculture, Forest Service, Climate Change Resource Center. https://www.fs.usda.gov/ccrc/topics/global-carbon
