The carbon cycle is a part of our daily lives, although most of us probably wouldn’t realize just how personally it affects us. The carbon cycle is directly linked to the food we eat, the air we breathe, the electricity that powers our lights, televisions, and computers, the fossil fuels that power our cars, even the fertilizer we use in our gardens. Our role in the carbon cycle is important, as we not only are affected by the carbon cycle, but we influence the carbon cycle as well. As we begin to experience some of the predicted effects of climate change, foresters are studying how our forest management decisions influence this dynamic system.
The delicate balance of life on our planet is regulated by innumerable processes and cycles. These cycles, such as our water cycle (evapotranspiration cycle), nutrient cycle, and the carbon cycle, are all dynamic systems whose productivity changes over time, a slow response to changing outside influences. Climate change influences all ecosystem functions, including the carbon cycle. Climate change affects the rate at which carbon is released into the atmosphere and likewise influences the rate at which plants take in, or sequester, atmospheric carbon into their biomass. As forests take up about 30% of the total global land area[1], understanding how forests sequester carbon helps to inform and guide forest management decisions.
The Carbon Cycle and Climate
Carbon is everywhere. We are made of it, we eat it, and our entire civilization is built on carbon. Carbon is the fourth most abundance element in the Universe. Most carbon on earth (about 65,500 billion tons) is stored in rocks. The remaining carbon flows between reservoirs in the carbon cycle, such as the ocean (85%), atmosphere (2%), plants, animals, people, soils (5%) and fossil fuels (8%).[2]–[3] Changes within these “active” parts of the carbon cycle influence the rate at which carbon is made available or released from other components in the cycle. The cycle through which carbon moves through these reservoirs over millions of years is known as the slow carbon cycle. Carbon moving through biological processes (transpiration by plants, decomposition, etc.) is known as the “fast carbon cycle.” As most cycles in nature do, the carbon cycle on Earth manages to maintain a balance that keeps carbon cycling through these reservoirs, instead of releasing it all into the air or storing it all in rocks.3
Why does the carbon cycle matter to us, and why especially now? Understanding the carbon cycle helps to understand climate change and our role in it. Climate is affected by the carbon cycle. When the sun’s rays penetrate earth’s atmosphere, the warmth from solar radiation is returned to the earth from the atmosphere in the form of heat radiation. Gases in the atmosphere like carbon dioxide (CO2) absorb this heat and radiate the heat energy to the earth’s lower atmosphere and surface.2 When humans release more carbon into the atmosphere in the form of CO2, the atmosphere absorbs more heat radiation from the sun and thereby increases overall surface temperature on earth. For eons the carbon cycle has remained in balance among its various reservoirs, keeping the earth’s temperature balanced over time, like a thermostat. However, humans have disrupted this balance since the Industrial Revolution, releasing carbon at an unprecedented rate. At the beginning of the industrial revolution, CO2 concentrations were at 280 parts per million (ppm); today that number is 387 ppm, a 39% increase2. Our role in altering the balanced system of the carbon cycle is clear – and the activities responsible for this disruption should remain important to us on a daily basis.
Human Impact on the Carbon Cycle
Humans have a significant impact on the carbon cycle predominantly from two activities: burning fossil fuels and deforestation. Fossil fuels are derived from stored carbon. If all the fossil fuels stored in the layers of soils on the planet were left intact without human interference, the carbon within those reservoirs would slowly return into the atmosphere over millions of years, either through volcanic activity or through the slow carbon cycle. When we burn fossil fuels in the form of oil, coal and natural gas, we release enormous amounts of carbon into the atmosphere, moving it from the slow carbon cycle to the fast carbon cycle.2 For perspective, the total concentration of carbon stored in rocks is 65,000 billion metric tons; in 2009, humans released 8.4 billion metric tons of carbon by burning fossil fuels. This means in one year, humans burned almost 1/8 of the carbon stored in rocks on the entire planet.
Deforestation plays a large role in the amount of carbon released into the atmosphere as well. Over 30 million acres of forests and woodlands are lost every year due to deforestation. According to the Environmental Defense Fund, 32 million acres of tropical rainforest were cut down each year between 2000 and 2009.7 The primary cause of deforestation is to clear land for livestock and crops including sugar cane, palm oils, and corn production8. It is estimated that more than 1.5 billion tons of carbon dioxide are released to the atmosphere due to deforestation, mainly the cutting and burning of forests, every year.4 Forests are one of the many “reservoirs” that store carbon on land in the form of plant and animal life. When we cut down a forest, our influence on the carbon cycle increases exponentially. Deforestation removes the plants and trees that otherwise would have sequestered carbon out of the atmosphere into their biomass, reducing the forest as a reservoir for carbon storage. Uprooting stands of trees leaves soils exposed, releasing stored carbon from lower soil layers. In developing nations, these trees and plants are frequently burned, releasing the stored carbon into the atmosphere quickly. Forests store more than 100 times more carbon than the agricultural land typically replacing these removed forests.4
Forest Management and Carbon
Scientists studying management strategies recognize that no single solution is the answer to all challenges, especially within a dynamic system. Chasing this “moving target” – if you will – underscores the importance of diligently monitoring and testing multiple approaches to carbon management in our forests. According to a study conducted in December 2007 called “Climate Change and Forests of the Future: Managing in the Face of Uncertainty,” a mix of both mitigation and adaptive strategies that best suit the conditions of the forest and region should be employed, with flexible approaches that can be modified as conditions change.6
Given the significant role forests play in the carbon cycle, the U.S. Forest Service has created the “Forest Service Strategic Framework for Responding to Climate Change.” 5 The plan contains a comprehensive structure for addressing carbon sequestration and climate change including scientific research, adaptation, mitigation, policy measures, sustainable operations, education and alliances.
Forest Service officials in Monongahela National Forest (MNF) in West Virginia are using this framework to design a comprehensive forest management plan that prescribes specific adaptive and mitigation strategies to address climate change. One of the top priorities of the plan is to restore red spruce to MNF as an adaptive strategy; promoting cooler temperatures, moister conditions, and enhancing ecosystem resiliency will help forests adapt to climate change. Restoring red spruce serves a mitigation strategy to help reduce the effects of climate change by promoting carbon sequestration. The management plan was recently presented at the first joint meeting of the Central and Southern Appalachian Spruce Restoration Initiatives (CASRI and SASRI, respectively) at which SHR presented its own spruce restoration program.
We are faced with an unprecedented amount of carbon being introduced to the atmosphere with an almost certain influence on the carbon cycle. Our ability to adapt and mitigate these effects will be determined by the successful application of the appropriate management strategies, thereby reducing our effect on climate change.
Here are a few ways we can reduce our carbon footprint every day:
- Reduce use of fossil fuels – walk, use public transportation, carpool, combine trips
- Recycle – recycling reduces the demand for virgin materials to make new products and requires less energy to produce new products from recycled materials than virgin materials.
- Compost – Composting reduces the amount of material transported to landfills by processing the material at your home. Plus, it provides great fertilizer for your garden!
- Plant Native – Choosing native plants for your garden improves ecosystem resiliency
- Reduce consumption of animal products – Reducing meat consumption reduces the demand for forested land for livestock production, thereby reducing deforestation.
- Choose products for their sustainability value – select products with high sustainability value, like paper certified by the Forest Stewardship Council.
- Buy Local – purchasing products made locally reduces the amount of fossil fuel burned transporting goods to your door.
[1] https://www.greenfacts.org/en/forests/
[2] https://earthobservatory.nasa.gov/Features/CarbonCycle/
[3] http://carboncycle.aos.wisc.edu/
4 http://www.climateandweather.net/global-warming/deforestation.html
6 http://onlinelibrary.wiley.com/doi/10.1890/06-1715.1/full
5 https://www.fs.usda.gov/Internet/FSE_DOCUMENTS/stelprdb5158964.pdf
7 https://www.scientificamerican.com/article/deforestation-and-global-warming/
8 https://earthobservatory.nasa.gov/Features/Deforestation/deforestation_update3.php