Carbon Sinks

Question: how is a southern red oak (Quercus falcata) like Atlanta’s Lake Lanier? Answer: just as a reservoir stores water, an oak stores carbon.

Candler Street Hardwoods

Photosynthesis is the process by which a tree uses sunlight to convert carbon dioxide into new leaves and branches, a bigger trunk, and longer roots. All of that carbon absorbed by the tree is not forming part of a greenhouse gas, the kind that is contributing to global climate change.

We call a living tree a “carbon sink,” because it stores more carbon than it releases. Of course, when the tree dies, it releases that carbon back into the environment. Recently, an Agnes Scott student calculated that our trees store or “sequester” about 185 tons of carbon annually. Also, some of our trees shade classroom buildings and dormitories from the sun, thereby lowering the demand for fossil-fuel energy — from coal-burning power plants, for example — that releases carbon into the atmosphere.

building-dashboard A goal of the Office of Sustainability is that Agnes Scott College be climate neutral by 2037. That’s one reason we track, with our Building Dashboard, how much electricity we use and how much carbon we generate. And that’s why the 30-inch southern red oak behind this sign is more than a tree for us: it’s a carbon-filled reservoir that we want to keep healthy and growing as long as possible.