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In the US, the transportation sector represents the largest source of greenhouse gas emissions.  There are many different segments in our modern transportation systems, and they face different challenges in mitigating GHG emissions. Assessment reports from the Intergovernmental Panel on Climate Change (IPCC) gathers scientists from across the globe to assess available information about climate change based on published research. Paulina Jaramillo served as a coordinating lead author for the transportation chapter of the newly released report from Working Group III, part of the sixth climate assessment report.

The IPCC has existed for over 30 years to provide its 195 member-countries with scientific information to inform climate policy development. The assessment from Working Group III was prepared by 239 experts from around the world and provides a comprehensive summary of opportunities for mitigating the greenhouse gas (GHG) emissions that contribute to climate change. As one of three coordinating lead authors for Chapter 10, Transportation, Jaramillo, a professor of engineering and public policy, led more than a dozen fellow experts in evaluating the state of knowledge about mitigation options for the sector.

Strategies that reduce demand for transport services could support mitigation efforts for the sector, but low-carbon technologies are also needed. Many authorities are already taking action with light-duty vehicles, personal vehicles, and public transportation systems by pushing for vehicle electrification. Jaramillo believes that this is important and will only continue growing as our primary means for reducing emissions from these sources.

Our chapter includes several cross-cutting boxes, such as how changes in urban form would affect transportation.

Paulina Jaramillo, Professor, Engineering and Public Policy

Other segments of transportation may require different low-carbon fuels. For example, low carbon hydrogen could drive emission reductions from heavy-duty and long-distance transport.

Finally, Jaramillo highlights that reducing emissions from shipping and aviation will remain a challenge for years to come. Decarbonizing shipping and aviation will likely require advancements in hydrogen-derived fuels like ammonia or synthetic hydrocarbons. These solutions still need improvements in electrochemistry and carbon dioxide removal. Researchers like Shawn Litster, professor of mechanical engineering, are advancing the electrochemistry of producing hydrogen and its use in transportation and stationary power with fuel cells.

While Jaramillo and her co-authors focused on emissions from transportation, she noted that transportation overlaps with many other domains, as reflected in the full summary for policymakers. “Our chapter includes several cross-cutting boxes. For instance, there’s a cross-cutting box about urban form and how changes in urban form would affect transportation.” Jaramillo said. “Similarly, low-carbon power generation and hydrogen production fall within the scope of the energy chapter, chapter 6, which highlights the interdependencies of the systems.”