Greenhouse gases (GHGs) include gases such as carbon dioxide, water vapor, methane, andnitrous oxide. Solar radiation (sunlight) is absorbed by the Earth and released back into space. However, GHGs in the atmosphere absorb the energy that is trying to leave and radiate it back tothe Earth. More energy is reabsorbed than is released; excess heat is prevented from leaving theatmosphere. This imbalance leads to global warming. Emissions from human activities are increasing the amount of GHGs in the atmosphere, which is exacerbating global warming. GHGs are measured in metric tonnes of carbon dioxide equivalent, or MTCO2E.

All GHGs have a different Global Warming Potential (GWP). This is the amount of heat absorbed by each gas in the atmosphere; the higher GWP a gas has, the more it will exacerbate global warming. Methane is 28 times as potent as carbon dioxide and nitrous oxide is 2665 times more potent than carbon dioxide (IPCC). The unit of measurement for emissions, MTCO2E, scales methane and nitrous oxide emissions to their carbon dioxide-equivalent emissions, so that all emissions are in terms of carbon.

Colorado College keeps track of GHG emissions by sorting them into categories based on theirsource. These are called “scopes”:

• Scope 1 - Direct Institutional: Scope 1 emissions measure direct emissions from sources that are owned and/or operated by Colorado College. This includes natural gas for heating, gasoline and diesel for CC's vehicle fleet, and fertilizers and refrigerants.
• Scope 2 - Indirect Institutional: Scope 2 emissions measure indirect emissions from the generation of purchased electricity.
• Scope 3 - Indirect Behavioral: Scope 3 emissions are related to behavioral choices. CC has chosen to measure emissions from study abroad, faculty and staff commuting, student travel to–and from home, business travel paid for by Colorado College, solid waste and wastewater, and paper usage. These choices reflect CC's commitment to address and change the behavioral patterns that drive indirect emissions.

On January 1st, 2020, Colorado College officially became a carbon-neutral institution.According to the Natural History Museum of the UK, “a person, company, or country is carbonneutral if they balance the carbon dioxide they release into the atmosphere through theireveryday activities with the amount they absorb or remove from the atmosphere. This is alsocalled net zero carbon emissions or net zero carbon, because overall no carbon dioxide is addedto the atmosphere” (NHM). CC’s status as a carbon-neutral institution does not mean that thecollege doesn’t produce carbon emissions. Any gross carbon emissions still generated by CC are balanced out by carbon offsets purchased by the college.

This year’s technical report is the first to fully account for carbon neutrality. It is important to note that last year’s (FY20) greenhouse gas inventory occurred across the fiscal year, whereas CC reached carbon neutrality at the beginning of the calendar year. This means that carbon neutrality was met halfway through the emissions reporting period. For last year’s report, Colorado College appears to be “half” carbon-neutral because offsets could only be applied to emissions from January 1st, 2020 onward. This year’s data (FY21) fully captures Colorado College having met carbon neutrality.