|This month, we continue our Sustainability Series with Dr. Petrie, as we explore the Carbon Cycle and its role in Global Warming.
Carbon Cycle & How CO2 Plays into Global Warming
We continue our sustainability series with Dr. Russ Petrie. Wildfires have plagued the state of California for the past several months. Dr. Petrie explains below how our actions play a role in the carbon cycle and why reducing our carbon emissions is an urgent global problem.
Q: What is the “Carbon Cycle”?
A: The carbon cycle is the process in which carbon travels from the atmosphere into organisms on earth and then back into the atmosphere. The earth is a closed system, so the total amount of carbon does not change, it simply cycles from one reserve to another – whether it’s stored in trees and rocks, or even the ocean. The carbon cycle is the ultimate form of recycling and is an essential and natural process for the survival of all living things. Through our actions, we as humans have caused an imbalance in the cycle, through the burning of fossil fuels, emitting more CO2 than the cycle can handle, thus leading to global warming.
Q: Break it down for us. How does it work?
A: The Carbon Cycle is broken into four main processes: Photosynthesis, Respiration, Decomposition, and Combustion. Plants use energy from the sun to take in carbon dioxide and water from the atmosphere during Photosynthesis. Using the carbon dioxide as fuel, they release the oxygen back into the atmosphere. Animals continue the cycle by breathing the oxygen and then eating the plants which allows the carbon stored in the plants to be absorbed into their bodies. When animals exhale, they release carbon dioxide, which can then be absorbed again by the plants. Once the plants or animals die, they begin to decompose, releasing more carbon dioxide and methane into the atmosphere. However, not all dead plants or animals immediately decompose. Sometimes their remains are absorbed by the soil and locked in underground deposits. Over hundreds of years, layers of sediment build up on top and compress these remains, forming fossil fuels. Examples of fossil fuels include oil and coal.
Q: Does the carbon cycle happen in the ocean too?
A: Yes, in aquatic ecosystems, carbon dioxide dissolves in the water. Just as plants on land depend on CO2 for photosynthesis, aquatic plants do too – and just like plants on land, they give off oxygen, which fish use to breathe. In nature, there is a natural balance between the carbon dioxide in the air and carbon dioxide in the water. If the balance is disrupted by an increase in carbon dioxide in the air, CO2 increases in the water as well, and the water becomes more acidic. Acidification of the oceans makes it difficult for marine life to get essential oxygen needed to survive.
Carbon dioxide can also be pulled out of water by small single cellular organisms called diatoms, and other organisms such as cyanobacteria and microalgae. Like plants during photosynthesis, these diatoms also release oxygen, and in fact account for 20% of all the earth’s oxygen. Diatoms hold on to carbon and sink to the bottom of the ocean, “sequestering” the carbon.
Q: So where do humans come in?
A: The one step in the carbon process we have not discussed yet is combustion. The burning of fossil fuels has supplied energy to the human population for decades, but as the population grows, as do our energy needs, which means more combustion of fossil fuels. The combustion of fossil fuels releases carbon dioxide into the atmosphere. We are now burning fossil fuels at unprecedented rates and the environment simply can’t keep up.
Q: How does the Carbon Cycle contribute to climate change?
A: When we burn fossil fuels to release energy, by driving for example, we release carbon dioxide back into the atmosphere. Carbon dioxide is considered a “Greenhouse Gas.” If you envision the world as one giant greenhouse, the amount of carbon dioxide produced by plants in a greenhouse keeps the climate warm all year, allowing the organisms inside to grow regardless of the outside temperature.
With more cars than ever on the roads, and more global production of materials in factories, we are causing an imbalance in the air quality by releasing significant amounts of CO2, trapping the heat in our atmosphere, and warming the planet.
Q: What does this mean for us?
A: In California, where I live, the destructive forest fires you may have seen on the news recently are attributed to conditions caused by drier, hotter temperatures. These fires are part of the carbon cycle too. These forests that have been around for hundreds of thousands of years, and each tree has large stores of carbon inside. When the trees burn, the carbon is released into the atmosphere in the form of CO2. More CO2 in the atmosphere means warmer temperatures and the cycle continues.
Q: How can we work toward re-balancing the carbon cycle?
A: This is going to require a global effort. Companies around the world have committed to reducing carbon emissions produced by the production, transportation, and manufacture of their products. This is vital to continuing to make the earth hospitable for future generations.