By: Nick Santangelo

After decades of declining populations, Philadelphia has been on the rise since the Great Recession. Millennials and others have increasingly left the suburbs, joining Temple University in calling Philly home. They're not alone in this movement. More than half of the world's population now lives in urban areas. But what effects are increased urbanization having on local climates?

The answer is something several presenters at the College of Liberal Arts' recent Sustainability Symposium are searching for. During the symposium, Professor Hamil Pearsall of the College's Geography and Urban Studies Department asked the audience during a panel discussion what the implications of a hurricane and, more broadly, global climate change might be on cities like Philadelphia. Dr. Pearsall then advocated for strengthening urban sustainability research while challenging her peers to consider what sort of technology is and is not useful to cities in parsing data to find urban sustainability solutions.

Later in the day, Philadelphia Office of Sustainability Deputy Director Sarah Wu gave a presentation highlighting just why finding these solutions is so critical to Philadelphia's future. A statistic she shared seemed to genuinely shock the audience.

"The hottest neighborhoods in Philadelphia are 22 degrees hotter than the coolest neighborhoods," said Wu. "Twenty-two degrees. That's crazy!"

It seems impossible, but the data doesn't lie. The air temperatures between, say, Point Breeze, Fishtown and Manayunk can vary wildly in the same day. One of the major factors behind these erratic is what's on the ground and what's protruding from it. More research is still needed to discover precisely how much of an effect particular types of ground coverage have on air temperature changes. What the City does know, however, is that having trees in one spot versus concrete in another versus a mixture of grass and rocks in yet another space plays a major role in these fluctuations.

Arizona State University Professor B. L. Turner II spoke at length about how he's researching these and other environmental consequences of urban design decisions in Phoenix.

Dr. Turner opened his presentation by asking, "Can you redesign urban landscapes in a way that reduces their environmental impact?"

Called "land system science" and "land system architecture," this type of research explores how individual plots of land are used and covered and how cities are configured. Dr. Turner said multiple tradeoffs are necessarily made in urban design, but "ideally the land system is treated as a social-environmental system."

The professor has a lot of work ahead of him still, but he has a working hypothesis: "land configuration is often as or more important than composition and shape can be and as important as pattern in shaping the environment and thus the sustainability of urban areas."

Part of why this is such an important issue is that the land configurations Phoenix residents want may not be congruent with what's most sustainable. For instance, pools have a huge impact on land temperature while trees have a more significant effect than grass.

Beyond furthering the cause of climate sustainability, there is also a practical, economic impact of Dr. Turner's study. Land surfaces developed in certain ways can keep residents' heating and cooling costs down.

Of course, it's not as simple as identifying the ideal land cover makeup and having every city and resident comply with it. Economics, politics, aesthetics and a host of other factors affect how urban municipalities develop their land. City landowners, too, have concerns beyond just lowering their bills. Any hopes for urban development to occur in a sustainability vacuum are likely unrealistic.

"What does this mean on the socio-economic side? Do people want landscapes that look like that?" asked Dr. Turner. "People will pay a lot more money in Phoenix if they can have water and grass. And if they can't have water and grass, the land value falls off."

But something has to give if society continues urbanizing. If that something is just increased climate change, the consequences are much more far-reaching and dire than property values.

"With climate change, there's a chance that the climates we currently experience in Phoenix could become the norm in other places," said College of Liberal Arts Assistant Professor Ariane Middel during a symposium panel.

Dr. Middel's research "examines how urban design affects microclimate and comfort." But she noted that "comfort" as a metric is extremely subjective. While everyone relies on weather reports to understand what the temperature, different temperatures mean different things to different people. When you ask someone what the weather is like outside, they might tell you it's cold or warm, but there's a chance you'll disagree with their assessment when you step outside yourself. To overcome this, Dr. Middel built a robotic cart that more accurately measures how people experience comfort than simply looking at the temperature would.

The Geography and Urban Studies professor is looking at another Arizona city, Tempe, along with Buffalo, N.Y. to figure out what sort of climate and comfort data cities most need to implement effective sustainability strategies. Dr. Middel hopes her work will help "close the gap between the heat mitigation research that's been done and the results and the implementation at the city level."

If cities fail to implement sustainable development plans, the magnitude of climate change's effects could be enormous, explained Dr. Turner. By 2050, Boston summers could mirror those of Washington, D.C. today.

Dr. Middel thinks the College of Liberal Arts can be a major player in preventing that potential future from becoming reality. She shared some thoughts on how to make it happen. "In order for Temple to become a leader in sustainability science, I think it's very crucial that people share research and take risks across departments."

In Temple University Executive Vice President and Provost JoAnne A. Epps, she has an ally. The Provost also wants the College of Liberal Arts to be at the forefront of climate change mitigation. "I believe very strongly that sustainability is one of the most important things that face us on this planet," said Epps. "I don't think I'll be alive when we get there, but I think we'll understand the impact we have on our environment."