By: Nick Santangelo

"The clear message from the science is temperatures are clearly increasing, and this has basically been the message through the last several IPCC reports," Karen Seto told a crowd of Geography and Urban Studies, Geographic Information Systems and Environmental Studies students last week in Alter Hall.

Dr. Seto, a Yale University professor, was appearing as part of an event sponsored by the Center for Sustainable Communities. While on campus, she spoke about her experiences as a co-lead author on the Intergovernmental Panel on Climate Change's (IPCC) 2014 and 2021 reports' urban mitigation chapters. During the fall 2018 semester, the latest update to these same series of reports led the College of Liberal Arts' (CLA) Geography and Urban Studies faculty to ask the CLA community the big question: can humanity avoid a climate breakdown?

In her visit, Dr. Seto challenged students to consider that question through the lens of cities, like Temple University's home of Philadelphia. The 2014 report was the IPCC's fifth but the first to include a chapter specifically on urban areas. Over 110 pages, the authors identified seven key messages in regards to the role cities are playing in leading the world towards a 1.5-degrees Celsius increase in global temperature since the start of the Industrial Revolution by 2040.

Key Message 1: Urban areas are major focal areas for the majority of global energy use and CO2 emissions.

Cities are using a whopping 67-76 percent of the world's energy and generating 71 to 76 percent of its CO2 emissions. Even though many cities have made conscious efforts to be more efficient, that can't outweigh the massive energy use and CO2 output of cities in the developing world.

Key Message 2: Urban densities are declining worldwide.

When cities are denser, they tend to have lower carbon footprints and use up less energy. Unfortunately, the world's cities are trending toward more sprawl and less density.

Key Message 3: Increasing urban density is a necessary but not sufficient condition for lowering urban emissions.

Dr. Seto said that "it's not good enough" to have high densities alone. That's because this strategy can't make up for land use that's strictly commercial or residential. Cities that are both high-density and have mixed land-use areas (providing easy access to jobs, housing and shopping) are what's really needed to lower emissions. "If there's one thing that cities can do more than anything else," explained Dr. Seto, "it's thinking about accessibility."

Key Message 4: Infrastructure build-up over the new few decades will result in significant emissions.

But there is a way to mitigate this problem. On the broadest level, the cities of tomorrow cannot be built like the cities of today were. "That's why I'm reaching out to those of you in the room who are just starting your careers in terms of where you can make an impact," said Dr. Seto.

Key Message 5: There are large mitigation opportunities in emerging economies, but they often have limited financial and institutional capacities.

Looking out Alter Hall's seventh-floor windows toward Center City, Dr. Seto pointed to the Comcast Innovation and Technology Center and quipped that it seems like there's a new skyscraper in town every time she visits. But while Philadelphia may be a city constantly reinventing itself, it's nearly impossible to change its skeleton. But while emerging cities in the developing world may have more limited financial and intuitional resources than Philadelphia, they avoid the climate mistakes William Penn unknowingly made by building their city skeletons different from the start.

Key Message 6: Thousands of cities are undertaking climate action plans, but their impact on urban emissions is uncertain.

Cities are typically the most progressive places on Earth, and many have put forward plans to battle climate change. But while these plans might be well-meaning, Dr. Seto said they most often have either uncertain or low impacts on climate change.

Key Message 7: Most cities are focusing on a single sector-level mitigation strategy and do not use spatial planning as a mitigation tool.

Dr. Seto believes there may be a governance paradox in some cities. That means that historical legacies and regional and national government requirements constrain what each city can do. But what city leaders need to focus on is their ability to control how their land is developed.

Ultimately, reducing humanity's ever-expanding carbon footprint will be extremely difficult, and it won't be something that can be accomplished by technological breakthroughs alone. Sure, hybrid/electric vehicles, solar panels and wind turbines are helpful, but the technological problems are small compared to entrenched behavioral problems like driving to work instead of taking public transit or infrastructure problems like single-use plots of city land.

"If we're really going to reduce warming and reduce emissions," concluded Dr. Seto, "we need to break out of the technological behavior as well as the behavioral and infrastructural lock-in."