When you enter into any conversation about carbon neutrality, you’re likely going to hear people categorize the different types of greenhouse gas emissions into what are called “scopes.” This article will describe what greenhouse gases are, the differences between the scopes they are grouped into, and give you examples of what types of emissions fit into each scope from a University of Michigan perspective.
Greenhouse Gas Emissions
First, what is a greenhouse gas? A greenhouse gas is any gas in our atmosphere that traps heat from the sun. These gases make life on Earth possible because they regulate the temperature of our planet keeping it warmer than the cold temperatures out in space. You can think of them as working like a blanket or just like the glass roof of a greenhouse (hence the name) that lets the heat from the sun into the structure and then holds it there to keep the plants inside warm.
When it comes to climate change, the trouble occurs with the accumulation of greenhouse gases in our atmosphere, trapping heat. While we want our planet to be warmer than space, life on Earth is accustomed to a certain range of temperatures, and if we get too far above that range problems arise. Ice caps melt, traditional growing seasons for plants change, patterns of rainfall shift, and storms powered by warm tropical waters grow in intensity.
Another thing you may not know about greenhouse gases is how common they are. You’ve likely heard of many! They include water vapor, carbon dioxide, methane, ozone, nitrous oxide, and fluorinated gases.
Now that you know a little more about greenhouse gases, let’s talk about the scopes they are grouped into.
The first category is for emissions generated by the organization. Because these emissions are directly controlled by the organization, they are often the first to be measured and targeted for reduction. At U-M, scope 1 sources include on-site fossil fuel combustion at our Central Power Plant and emissions from our campus fleet vehicles, including our buses.
The second category is for indirect emissions from the generation of electricity, steam, heating, or cooling purchased by the organization. Although these emissions are not directly produced by the organization, the purchase records make them fairly easy to measure. In terms of reductions, this often involves agreements between the organization and the utility surrounding whether the energy will be produced from renewable or fossil fuel sources. At U-M, scope 2 sources include emissions that result from the electricity and natural gas we purchase from DTE Energy and Consumers Energy.
The third category is essentially the catchall for all other indirect emissions that result from an organization’s activities. Scope 3 emissions are often more challenging to measure and reduce because they are not under the organization’s direct control. At U-M, scope 3 sources include emissions that result from purchased goods and services, U-M-sponsored travel, commuting, and waste disposal.
And, there you have it! If you’d like to learn more about emissions scope categories, check out page 7 of the U-M President’s Commission on Carbon Neutrality Fall 2019 Interim Report.