Activities beyond campus – such as business air travel, student commutes and purchases of goods like lab equipment – account for more than 60% of Cornell’s carbon emissions, according to new research that analyzed the university’s greenhouse gas consumption through the lens of the COVID-19 pandemic.

“We used the COVID pandemic opportunity to figure out hotspots of our campus carbon emissions, to identify opportunities for making Cornell greener and carbon-neutral,” said Fengqi You, the Roxanne E. and Michael J. Zak Professor in Energy Systems Engineering at the College of Engineering “We sought opportunities for improvements.”

You is a senior author of “COVID-19 Impact on an Academic Institution’s Greenhouse Gas Inventory: The Case of Cornell University,” which appears in the forthcoming Journal of Cleaner Production, Aug. 20.

As Cornell has taken steps to reduce carbon dioxide emissions over the past two decades, addressing campus consumption may be the next green frontier. Using Cornell as a case study, the researchers created a framework aimed at helping universities reach their climate goals in the coming years; Cornell seeks to achieve carbon neutrality by 2035.

“Understanding what causes emissions leading to climate change is key to solving climate change,” said senior author Natalie Mahowald, the Irving Porter Church Professor in Engineering. “This research is an integral part of Cornell as a living laboratory. Cornell and the state of New York must be on the leading edge of achieving low-carbon lifestyles. “

Campus greenhouse gas emissions dropped from 463.5 thousand metric tons of carbon dioxide in pre-COVID 2019 to 404.7 thousand metric tons in 2020 at the starting phase of the pandemic, the researchers found. The shutdown also offered new insight into campus’s carbon usage overall.

The engineers divided their research effort into three different facets. Scope 1 focused on the greenhouse gas emissions resulting from sources located within the campus boundary, such as the university’s combined heat and power plant, which makes electricity and steam from a central location using natural gas. Cornell is drilling two miles into the ground now to see if Earth Source Heat may be a feasible way to heat campus.

Scope 2 examined the greenhouse gas emissions due to using grid-supplied electricity, heat, steam and/or cooling within the Ithaca campus boundary.

Scope 3 entailed measuring greenhouse gas emissions that occur beyond campus – such as when faculty, students or staff leave campus and attend conferences or conduct other Cornell business. This involves commuting, air travel, procuring laboratory and research equipment, and processing wastewater and solid waste.

For Scope 3, the engineers used the generally accepted Economic Input-Output Life Cycle Assessment approach to account for complex interactions among hundreds of industrial sectors of the economy and analyze material and energy needed throughout the supply chain for acquiring the equipment and other supplies – as well as taking an inventory of the carbon dioxide resulting from procurement.

The researchers found that Scope 3 contributed the largest share of Cornell’s greenhouse gas emissions (60.4%), followed by Scope 1 (37.8%) and Scope 2 (1.7%).

Early in the pandemic in 2020, Cornell greenhouse gas emissions dropped rapidly, but as faculty and students returned in fall 2020, emissions increased – with very little academic travel – the researchers noted a sharp decline in Scope 3 emissions.

This meant that transitioning Cornell to consider how sustainable consumption plays a key role for a green campus, the paper said. While energy and managing greenhouse emission is important to sustainability, procurement is becoming a crucial issue in campus management.

“We show that looking at our procurement and reducing emissions from it – either through cutting high carbon-dioxide products, or by influencing vendors to cut their carbon footprint – is vitally important to achieving climate-change temperature targets,” Mahowald said. “While converting our power sector to renewables as fast as possible is incredibly important, it is not sufficient to lead to a low-carbon temperature target: Getting the products we buy to be low-carbon is required as well.”

In addition to Mahowald and You on this research, the other authors are former postdoctoral researcher Lu Sun, Max Frasier Kaufman ‘23, Emerson Allen Sirk ’19, M.S. ‘21, and Siddarth Durga M.S. ‘20.

The Cornell Atkinson Center for Sustainability funded the work. Sarah Carson, director of the Campus Sustainability Office and Michael Winters, director of Campus Services, supplied collected data and explained procurement budget procedures.