MADISON, Wis. – New research from the University of Wisconsin-Madison finds that reaching net-zero emissions by mid-century will substantially improve public health in the U.S. However, climate strategies that heavily depend on carbon dioxide removal (CDR) are likely to lead to worse pollution, air quality and climate-related premature deaths than scenarios that prioritize direct emissions reductions and rely less on CDR.
Published in Nature Climate Change, the new study led by Postdoc Fellow Candelaria Bergero and featuring Assistant Professor Morgan Edwards of the La Follette School of Public Affairs finds that decreased CDR reliance in achieving net-zero emissions by 2050 results in about 33,000 fewer premature deaths annually in 2050 compared to an alternative scenario that incorporates higher CDR.
CDR refers to a collection of approaches for removing CO2 from the atmosphere and durably storing it for decades to millennia. Examples of conventional methods include planting trees and using soil to capture carbon. Newer methods include technologies such as direct air carbon capture and storage (DACCS), which uses chemicals to capture the heat-trapping gas directly from the air, and bioenergy with carbon capture and storage (BECCS), which captures and stores CO2 from processes where biomass is converted into energy.
These approaches have gained in popularity in recent years as researchers, activists and policymakers have sought a variety of strategies to reduce emissions and meet the Paris Agreement mandates that aim to reach global net-zero greenhouse gas emissions by 2050 to limit global warming to 1.5 degrees Celsius above pre-industrial levels. While CDR strategies can be important tools in reducing emissions, previous research by Edwards indicated that policymakers should not over-rely on CDR in pursuit of combatting climate change.
“As countries transition to net-zero emissions, it is important to understand that there are multiple pathways for achieving this goal, and each will have different implications for people,” Bergero says. “Through this study, we explore one of these implications – air pollution – and assess the distribution of impacts across race-ethnicity and income.”
Bergero, Edwards, and their co-authors used a state-of-the-art integrated assessment model with two CDR-level scenarios – along with air quality and epidemiological models – to evaluate community-level U.S. health benefits in net-zero emissions scenarios.
Both of the net-zero scenarios substantially reduce particulate matter concentrations and related premature mortality compared to a business-as-usual scenario in the study’s model, but the low-CDR pathway produces much larger health benefits because it leads to lower CDR-related emissions and lower residual fossil fuel use. It also would lead to lower emissions that result from some CDR methods themselves. Air quality-related deaths decline from roughly 203,000 annually in the business-as-usual scenario to 159,000 in the high-CDR scenario and 127,000 in the low-CDR scenario.
Importantly, across the 15 largest U.S. cities – home to over 100 million people – decreasing CDR reliance reduces existing inequalities by leading to greater reductions in pollution exposure for low-income and non-white communities, according to the study. Low-income and non-white communities in the U.S. currently experience higher pollution burdens.
“Solving the climate problem does not automatically solve air pollution and its unfair impacts. It can help a lot, but the biggest improvements in air quality and environmental justice will take planning,” according to co-author Steven J. Davis, who is a professor at Stanford’s Doerr School of Sustainability.
This research is part of a broader portfolio of work led by Edwards at the Climate Action Lab at UW-Madison. In the lab, Edwards, Bergero, and other climate policy scholars use energy and environmental data, systems modeling, and policy analysis to create equitable and inclusive solutions to the climate crisis.
Edwards is also lead author for the recently released third edition of The State of Carbon Dioxide Removal report and a member of the group’s executive team. Their ongoing reporting serves as the most comprehensive, sustained analysis and assessment of CDR development across the globe.
