As organizations increasingly aim to reduce their carbon footprints, a new study from the Massachusetts Institute of Technology (MIT) highlights significant differences in the societal benefits of various climate actions. Researchers found that while actions like purchasing renewable energy or reducing air travel may cut carbon dioxide emissions, their impacts on air quality can vary dramatically.
Through an innovative modeling approach, MIT researchers assessed the air quality implications of these actions, using data from three organizations in the greater Boston area. Their findings indicate that air travel can cause approximately three times more damage to air quality compared to equivalent reductions achieved through electricity purchases.
The study, published in Environmental Research Letters on March 1, 2024, reveals that major air pollutants, such as ground-level ozone and fine particulate matter, can lead to serious health issues, including cardiovascular and respiratory diseases, as well as premature death. The researchers emphasize that the geographical context plays a crucial role; for instance, the air quality impacts of energy use are often localized, while the effects of air travel can have a far-reaching, global influence due to emissions occurring at higher altitudes.
Noelle Selin, a professor at MIT and the senior author of the study, stated, “If we are trying to get to net zero emissions, that trajectory could have very different implications for other factors we care about, like air quality and health impacts.” She stressed the importance of structuring emissions reductions in a way that maximizes societal benefits.
The research team, which included lead author Yuang (Albert) Chen and other experts from MIT and Imperial College London, sought to quantify whether organizational actions that remove similar amounts of CO2 would yield equivalent benefits for air quality. “From a climate standpoint, CO2 has a global impact, but air quality impacts are driven by co-pollutants that act locally, making the location of emissions crucial,” Chen explained.
The researchers utilized a systems-level modeling approach, integrating data on organizational energy consumption and air travel. They analyzed emissions data from power plants, aviation routes, and the associated health impacts of air pollution. This comprehensive modeling allowed them to monetize the air quality impacts in relation to climate damages, providing a clear financial perspective on the two issues.
The study found that the monetized climate costs of CO2 emissions are approximately $170 per ton, while the air quality damages associated with electricity purchases amount to an additional $88 per ton. In contrast, the damages from air travel rise significantly to $265 per ton. These figures illustrate how the air quality impacts of emitted CO2 are highly dependent on the source and method of emissions.
Chen pointed out an unexpected finding: “Aviation impacts places that are far from these organizations. Not only are flights more damaging, but the pattern of damage differs significantly compared to energy systems.” The researchers noted that airplane emissions, which occur at high altitudes, can be carried across continents, exacerbating air quality issues in densely populated regions like India and China.
In a more focused analysis, the researchers investigated short-haul flights, discovering that they have a relatively larger impact on local air quality compared to longer domestic flights. Selin suggested that organizations aiming to benefit their communities might consider reducing short-haul flights as a viable strategy.
Furthermore, the location of emissions also influences the health implications. For instance, the study found that emissions from a university in a densely populated area resulted in an estimated 16 percent more premature deaths compared to those from a corporation operating in a less populated region, despite both having identical climate impacts.
Looking ahead, the researchers plan to extend their analysis to other modes of transport, such as train travel, to assess potential benefits from replacing short-haul flights. They are also interested in examining the air quality impacts of various energy sources across the United States.
This research was partially funded by Biogen, Inc., the Italian Ministry for Environment, Land, and Sea, and the MIT Center for Sustainability Science and Strategy. The findings aim to guide organizations in making informed decisions about their climate actions, ultimately leading to enhanced public health outcomes.
