Dr. Timon McPhearson on Using Ecology to Weather Climate Change

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Dr. Timon McPhearson, urban ecologist at the New School, the Stockholm Resilience Center, and the Cary Institute of Ecosystem Studies.

Interview by: Sam Bartusek

Timon McPhearson’s work concerns the most fundamental questions about our future on this planet. He’s based at the New School in New York City and has advised the NYC Mayor’s Office of Recovery and Resiliency, the MillionTreesNYC Committee, and the United Nations. His work has been published widely, including by Nature, The New York Times, and more. He studies the ecology in, of, and for cities, and he spoke with us recently about how urban ecology can improve resilience and sustainability in cities, and how humans can move forward in a changing climate.

Follow him on Twitter: @timonmcphearson

SB: Thanks so much for taking the time to talk today. Could you start off with a little about yourself and your field?

TM: Sure! I’m an associate professor at the New School and I direct the Urban Systems Lab there, where we focus on understanding the complexity of cities and urban systems, and on advancing an ecological perspective on cities as a way to shift towards more sustainable environments.

We’ve been doing a lot of work recently on resilience, adaptation and climate change in the context of cities. I’m trained as an urban ecologist, and what that means for me and for the work that we do in the lab is thinking of a city as you would any other ecosystem, and using that systems approach as a way to examine the interactions and dynamics of what a city is doing, in terms of its people, its infrastructure and its ecosystems. So it’s not necessarily, as people tend to assume, working on ecosystems inside cities, but rather taking the systems approach which was developed a hundred years ago in ecosystem ecology and applying it to the urban setting.

SB: What did you focus on studying in college and graduate school?

TM: In undergrad I studied Environmental Biology, and in graduate school I really wanted to get deeper into that so I went straight from undergrad to a PhD from Rutgers University in Ecology, Evolution and Natural Resources. I focused on community ecology, which is a one of the more narrow fields within ecology that looks at how species interact, what drives those interactions, and how they contribute to more ecosystem-scale dynamics like the stability of a system. But my familiarity with that systems perspective is what ultimately drove me, as I changed my career into looking at cities and urbanization, to take the same perspective in understanding the complexity of urban systems.

SB: Since leaving school, before you started teaching at the New School, what has your research and work focused on?

TM: It’s ranged, honestly. I tend to be someone who shifts around, because my interests are broad. Even in the work that we’re doing now, we have many different projects going in many different directions, and that’s pretty true of my career so far. I’ve done very laboratory-based work, for example in my dissertation work. I focused on building aquatic microcosms, small worlds in jars, and subjecting them to various environmental changes and studying their ecological dynamics, so it was mostly studying and counting protists under a microscope. Some of my later work though was very education-oriented, for the Hall of Biodiversity at the Museum of Natural History in New York, while I was a biodiversity scientist at their Center for Biodiversity and Conservation.

Then when I did my postdoc at Columbia University’s Earth Institute, I actually focused on building off the work I did in my dissertation around understanding cooperation in ecological communities. I was trying to bring that perspective into understanding the significant gap between religious and scientific communities in terms of recognizing the role and validity of evolution, so I taught a lot about evolution issues, including teaching an evolution, biology and cosmology class to priests at Union Theological Seminary as a way to try to bring science education into these communities that don’t necessarily have a direct link with scientists. It’s been a pretty broad career, but all environmental in some way, and I’ve always worked towards the goal of helping to train and motivate a more environmentally sensitive public and a more sustainable way of living through theory and practice.

SB: What does your research focus on right now?

TM: Right now I’m at the Stockholm Resilience Center at Stockholm University in Stockholm, Sweden. I’m a researcher affiliated with the center, and it’s a place I’ve been coming to for years because of the great work that they’re doing around resilience and systems-oriented thinking. And also because some of the collaborators that I really enjoy working with, particularly in urban resilience, are based here. I’m here for the summer to work on a few different projects. For example, we’ve just finished up work on a book called Urban Planet, which will be coming out from Cambridge University Press this fall.

I’m also co-leading with colleagues at the Center a new three-year project funded by Biodiversa and the EU Commission that’s about enabling green and blue infrastructure for climate change adaption in five European cities. We’re working in Barcelona; Oslo; Stockholm; Halle, Germany; and Łódź, Poland.

Green infrastructure in New York City (McPhearson, 2014).

We’re also working with New York City, where much of my research is based, as a benchmark in terms of how to use green infrastructure and ecosystems for climate change adaptation, and advancing that kind of on-the-ground planning and policy.

SB: Could you explain a little about green and blue infrastructure?

TM: Essentially it’s a certain way of thinking about ecosystems, most commonly in urban systems. One of the ways I think about cities is that they are simply chock full of infrastructure — they’ve got a lot of buildings, roads and in general all of this infrastructural technology (pipes, wires, wifi) that we use to generate human services such as making places to live, delivering clean water to drink or a place eat dinner at night. The concept of green and blue infrastructure is considering green and blue ecological spaces — roughly, vegetation and water — as infrastructure in and of themselves.

This means thinking about their role in providing services for people: How do they help clean the air, or how do they provide recreational space, or improve public health? Broadly, this is within a field we call ecosystem services, where I’ve done a bit of work over the past few years. Green infrastructural elements like green walls and roofs are something that architects, planners and designers are starting to bring into their work much more than they used to as a way to improve human services in urban environments.

SB: Since you’ve studied both resilience and sustainability, I’m wondering how you would explain the particular distinctions between those two concepts.

TM: That’s important to understand, because resilience and sustainability are often very conflated and sometimes used to mean exactly the same thing. Actually, three other colleagues at the Stockholm Resilience Center and I have a short correspondence on exactly this topic that came out in Nature last week, and the title of it is “Sustainability and Resilience Differ.” It’s the lead-in to a longer piece that we’re developing to try to explicitly lay out this difference.

Definitions of sustainability and resilience (after Folke et al. 2010 and Tuvendal and Elmqvist 2012).

In a nutshell, sustainability is a normative concept. In trying to achieve sustainability, we have sustainability targets and goals: zero waste, energy efficiency or renewable energy as opposed to more traditional fossil-fuels-based energy sources. These are all part of a suite of normative goals we have for a more sustainable society. Resilience, on the other hand, is a measurable property of a system, which is similar to the the way you might talk about stability — where a system can be stable or unstable, a system can be resilient or non-resilient. Sustainability is a bit fuzzier than that and isn’t necessarily a property of a system. That’s one key difference.

The other key difference is in how we work with each concept. With sustainability, you can set goals and targets and set yourself on a pathway there, so you’re either more or less sustainable. It’s either positive or negative progress, and that’s the normative component of it that I mentioned. With resilience, it’s different in that your progress on resilience can include both desired resilience and undesired resilience. Crime, for example, can be very resilient. It’s very hard to get rid of, so it’s become a persistent part of our system. On the other hand, there are components of our communities and cities that aren’t very resilient, which we want to improve and make more resilient, like the ability to weather extreme heat in cities and the ability to reduce risk and vulnerability to climate change. We end up wanting to enhance some kinds of resilience but decrease other kinds of resilience. Desired and undesired resilience are both properties of systems though, and so setting goals for “more resilience” doesn’t really make sense in light of the fact that cities, for example, can be resilient in ways we want and also resilient in ways we do not want. Additionally, if some part of the system is resilient, that doesn’t necessarily mean other parts of the system are also resilient, so this complicates statements or goals like “urban resilience.”

When you think about resilience and sustainability together, which is what planners and managers and policymakers are doing, the concepts often end up bundled together, confusing both concepts, especially since they can sometimes actually be in conflict. For example, Hurricane Sandy disrupted a critical networks that we had in New York City: it disrupted transportation, it disrupted the ability for people to be on their mobile phones because the wireless systems went out, it disrupted food and fuel supply, and one of the key reasons for these massive disruptions was because we did not have adequate backup systems. A more resilient energy system, for instance, would be one where you have less focus on efficient large-scale infrastructure and instead more disaggregation, modular and small-scale energy provision with redundancy and back-up systems. The energy system, like other subsystems of our cities, needs to be connected but you also need to be able to turn some things off and turn other things on, depending on what the situation is. A large scale centralized renewable energy source for New York City might meet our sustainability goals, but may not be resilient if lacking redundancy, modularity and back-up systems that can safeguard our need for energy during shocks or extreme events. So here there is opportunity for sustainability and resilience to be aligned, but if we don’t make good choices about the next generation of our energy systems, as one example, we could just as easily set sustainability and resilience in opposition to each other.

So, resilience requires redundancy. Conversely, one of the hallmarks of achieving a more sustainable society has been to focus on efficiency, and efficiency means reducing redundancy. Efficiency is one of the classic sustainability conflicts with resilience. This highlights the difference between resilience and sustainability, but to work with both concepts you have to recognize these conflicts and seek ways to achieve both desired resilience and pathways to achieve sustainability goals and targets. This means thinking about how you might reduce resilience to improve sustainability, or how certain parts of sustainability have to be rethought, like this focus on efficiency, because when a system is subject to some major change or disturbance you actually need that redundancy to be resilient.

SB: Especially in the context of extreme weather events, how could you use ecology to improve the resilience of a greater urban system, and/or the sustainability of it?

TM: I think of ecosystems as an important tool in the toolbox for climate resilience in cities. Let’s take the example that climate change is driving temperatures up in places all around the world. It’s going to get hotter in a lot of different places — if you look at recent downscaled climate projections, there’s almost no exception to the fact that cities are just going to get hotter and hotter. The intensity and frequency of heat waves, as well, is expected to go up. In New York City, which I know the best, we’re looking at a tripling of heat waves by between 2050 and 2080. So, what are the tools that we have in our toolbox for decreasing the impact of this heat?

Relationship between type of land cover and surface temperature on July 15, 2011. (Map created by Zoé Hamstead)

Green infrastructure is clearly one of the solutions. Of course, air conditioning is also one of the solutions. Cooling centers are a solution. Creating more social cohesion and more connected communities so that people can check on each other and help each other out during times of stress is also a solution — there’s a social response that’s part of the toolkit of solutions to reduce risk and vulnerability to heat waves. But cooling the city through green infrastructure is an important part of the solution suite, because vegetation through evapotranspiration makes the environment cooler, and because trees provide shade, which additionally creates coolness and cooling the city gets at the root cause of heat impacts. Ecosystems aren’t necessarily a silver bullet, but they’re definitely part of the solutions suite to adapting to climate change and building resilience in particular ways to some of the effects of climate change such as weather-related extreme events.

I gave the example of heat waves, but green infrastructure is a critical tool for dealing with flooding too — ecosystems, compared to pavement and buildings, absorb water and can hold onto it for short periods of time ameliorating the worst impacts of flooding. That doesn’t necessarily mean you don’t need other things too, like pipes and reservoirs and other ways of holding onto water temporarily so you can manage it during intense storm events, but they’re part of that solution suite. We know that during intense coastal flood situations communities in Southeast Asia that had intact mangrove ecosystems were able to attenuate storm surge and had decreased impacts of flooding. In temperate climates, communities that had large intact wetlands have been able to decrease the coastal impact of flood events. These are some of the examples of how ecosystems can be very effective in improving climate change adaptation and resilience-building.

An index of vulnerable social groups throughout New York City. (Map created by Zoé Hamstead)

SB: You mentioned that there’s also a social aspect — how might reducing social inequity factor into improving the resilience of a city overall?

TM: When you think about the impacts of extreme weather events, for example economic upheaval, the people that are impacted the most tend to be poor people and minorities. Depending on the event, it can be particular social groups: for heat waves, it’s often the elderly and small children, the elderly in particular. So in terms of the solutions for ameliorating the worst impacts of heat waves, these solutions such as green infrastructure are not evenly dispersed across the city, but rather are often less available to the most vulnerable and at risk social groups. At the same time, there are pockets in every city where you’re likely to have more or fewer elderly people, or more or fewer minorities, or high-income or low-income brackets. These social demographics are not random and they have hotspots, which do not generally coincide with the hotspots of some of our solutions for helping deal with the impact of a heat wave or flood event. So, this spatial mismatch in solutions and where the most at need live drive increased inequality — the groups that are particularly vulnerable because of their social class or their income status are further impacted because they don’t tend to have the parks or other spaces where they can receive some ecosystem-based amelioration of that intense heat wave or other weather-related event.

Combining a socio-economic vulnerability index with a heat vulnerability index shows areas with compounded risk. (Map created by Zoé Hamstead)

SB: From a bit of a different angle, when you’re constructing green spaces, how much does biodiversity matter as opposed to simply the quantity of green space?

TM: We don’t actually know the answer to that, even though it’s a fundamental ecological question. There is a bias among environmentalists, and certainly among ecologists, that biodiversity matters. I have this as a fundamental bias myself. But scientifically we haven’t studied it very well. There is not a lot of basic funding for research into understanding the relationship between biodiversity and particular ecosystem functions in cities, which means understanding what a functioning ecosystem does and whether that’s beneficial to us or not.

If you consider high-precipitation events that cause surface flooding, and the ability of a system to absorb that water and protect us from the worst impacts of flooding, does biodiversity really matter? Or are just a few plant and soil interactions able to provide water absorption well enough, meaning without a lot of different kinds of species? We don’t really know. There is some evidence that shows that for some functions biodiversity is critical, but there is also evidence that for others, not so much.

Green infrastructure in the form of a park in New York City. (Photo by David Maddox)

I think this is one of the crucial areas for research, and it’s the topic of some work I’m doing here at Stockholm that puts the focus not as much on the identity of the species but on what it does, which is to say species traits. Does a species have the traits that allow it to respond well to climate change and weather extreme weather events? Does it have traits that allow it to respond to a highly human-impacted polluted environment like a city? These questions are about species, but it’s not just from a species diversity, i.e. biodiversity, agenda. It’s rather understanding what they actually do, their functions, which a species can do or not do based on its functional traits.

SB: I want to ask the same question about native species vs. non-native species: Is it important to be using native species when constructing green infrastructure or is that something we don’t know much about either?

TM: Depending on who you ask you’ll get different answers. Certainly in the environmental and conservation community, the idea of native species has also been a fundamental bias. There are a lot of questions bound up in that idea though, such as what do we mean by “native” in an environment that’s changing so fast? If you go back two hundred years and ask what was native here then, it will be very different from now and also from what was native here ten thousand years ago, because ecosystems are always changing.

I think the question we should ask, regarding native versus non-native species, is what we want our ecosystems to do. There’s been a perspective in environmentalism since the 70’s, which has been largely unsuccessful as a conservation movement, that says species matter because they exist, and nature matters because it exists. This is something we call intrinsic value. I certainly personally believe nature has intrinsic value, but as an environmental agenda, arguing for intrinsic value has not been very successful in achieving conservation goals. That’s because there are no systems that aren’t dominated by humans: all systems are now in some form of management — or lack of management, which is also a management practice — by us, so it’s really the values that humans place on an environment that drive the changes in human dominated environments. That means we have to ultimately ask ourselves what we want a system to do. Do we want it to function to absorb stormwater? Do we want it to provide a nice space for hiking and recreation? Or do we want it to be what they call here in Scandinavia, a cultural landscape?

Here in Sweden I’ve noticed they prioritize cutting down certain kinds of trees and letting the cattle into the forest to graze, because they want the landscape to look and function like it did for the last thousand years. They want a certain aesthetic and certain species mix because that’s the human value of this landscape. In other places, the priority is for agriculture, or for a different aesthetic or cultural value. Human values shape the landscape intentionally or unintentionally.

Planting trees cools and beautifies a city, and sometimes non-native species will be more successful. (Photo by New York City Department of Parks and Recreation)

In some cases I think the answer to the question will be that native species are critical for specific functions and goals we have for ecosystems. But in considering what the landscape should do, or how it should look and feel for humans, your answer may be that non-native species are also very important. To give one example, in many cities planners, designers, developers want to have more green spaces, which often means more planting more trees. Trees cool the city, they make the city more beautiful, and they can drive real estate value up by as much as 15%. But which trees are going to be well adapted under climate change? Will what we plant right now still be well adapted fifty years from now? We may need to plant intentionally non-native species in order to have trees in some neighborhoods, because some species are going to be more susceptible to insect pests, to drought or to pollution, and the combination of those factors keeps changing on us. So, the choice of species comes down to our values and our goals, which of course may include nativity but ultimately depends on the traits those species have, and we still need more research to know whether the species with desired traits to meet our value-laden goals are native or non-native.

At the same time, those values and goals can shift a lot. Think about the cultural diversity within a city. By some accounts New York City has seven hundred languages spoken and it’s the most culturally diverse place on the planet. So how do you get people to agree on what they want? With gentrification and other temporal changes, every neighborhood in the city is undergoing change and goals for a neighborhood change over time. We have to get comfortable with the fact that what we ultimately think or value about nature is always shifting. I think that’s one of the most interesting elements of the way humans are interacting with and connecting with nature, the constant change in what we think is good or valuable.

Unused spaces such as rooftops, walls, and courtyards can be used as green infrastructure or to perform other valuable services. (Photo by Victoria Marshall)

SB: Could you explain a little bit about micro-urban spaces?

TM: Sure — this concept goes back to thinking about what our tools for improving livelihoods in cities are. To me, one of those tools is backing up and looking at the city and asking, what have we missed? I think one of the things we’ve missed is that small spaces can be very important. When we’re thinking about improving people’s lives outside of large projects, there are a lot of spaces that aren’t well-utilized in certain kinds of cities. For example, if you look at a lot of Asian cities, from my experience traveling around Southeast Asia and China, you see that back alleyways are highly vibrant areas, full of stalls and people, creating markets and exchanging goods and services. People will also plant plants in every little crevice, which you don’t see as much in western cities where they tend to be trash-filled, or dark or ignored.

Individually small pieces of vacant land in New York City (in yellow and red) add up to a large amount of space. (Graphic by Peleg Kremer)

Micro-urban spaces are the spaces in these crevices and cracks. Some of them aren’t crevices and cracks, they’re actually flat roof spaces that are still just black tar roofs that no one’s using, or they’re the space in between tall buildings, where you could have courtyards but there’s nothing there now. You could stand on roofs and look down and around, and you’d see all this space that actually exists in the city, without any management or activity in it, but is existing as small spaces. The idea of micro-urban spaces is that these small in-between spaces add up to a lot of space.

When we think about shifting a city to make it more sustainable, space is key. And in dense cities like New York or Tokyo or London or Mumbai, space is at a premium. It’s very hard to find large spaces, but large spaces aren’t our only tool in the toolbox. I think one of the things we need to learn to do is to take advantage of small spaces, using them to bring ecology back into the city in order to reinvent them as vibrant spaces for social interaction and increasing health and well-being of urban residents.

SB: I wonder if, in the same sense that ecology in those spaces can contribute to the ecosystem of the city as a whole, you think that suburban or even rural areas that may seem disconnected from the urban center can contribute to that whole ecosystem?

TM: Absolutely, and I think something that urban ecology as a field has thought about for a long time is understanding the linkages between urban core and peri-urban, suburban and even exurban spaces. The ecosystem services literature has done that a bit too, studying the flows of food, for example, which is grown in peri-urban agricultural spaces and comes into farmers markets in the city. There are a lot of linkages that are already there, whether it’s economic goods and services, or the movement of people themselves. There is vast flow back and forth between the urban and rural constantly, so one of the things we need to do, and that I would advocate is part of regional sustainability, is to focus on how we can maximize the connectedness between rural and urban areas, especially from a regional perspective.

Ultimately, global environmental change is not affecting the city with some kind of municipal boundary. It affects regions. Water scarcity, for instance, is affecting an entire region in the Middle East, and it’s affecting the entire southwest of the United States. Since the seats of power, money and decision making are in cities, however, they tend to focus within their municipal boundaries. It’s critical to understand the urban-rural linkages, because thinking from a regional perspective about governance and decision-making is critical for the future of highly connected regions.

SB: In that or a broader sense, what do you think are some barriers that are standing in the way of widespread implementation of strategies that scientists have agreed on?

TM: Short-term thinking. That’s a critical one, and you even find it in what tend to be hailed as some of the most progressive environmental and sustainability plans. Again, New York City is often held up as one of the leaders in terms of thinking about climate change adaptation and sustainability planning, and yet our plans are mostly only into 2030. For anyone who has a child right now, that child may well live to into 2100. Who’s thinking about 2100? Almost nobody. Most of our planning is for the next five years, and it has everything to do with our political decision-making cycles and the way in which we think about short-term returns, economically. Short-term thinking is fully ingrained in our way of living, in our economy and the political drivers behind many of the changes we make. We have to infuse longer-term perspectives even in our short-term decision making and the way we do business. I see it as one of the most important fundamental barriers for us to cross.

Another one, as I alluded to before, is thinking about regional governance. We have to recognize that people and ecosystems cross municipal boundaries, and changing climate has effects across municipal boundaries. We have to start responding to our environments in the way that they are, which is not driven by some kind of political boundary. That’s an arbitrary line but it’s the way we think about our economy and it’s the way we think about our politics and decision-making, so now we have to think about how to shift towards regional governance and decision-making.

SB: I know it’s a perennial struggle, but what’s the best way to bring science to policy makers and practitioners and make sure that it’s communicated?

TM: That’s tough. I think there’s responsibility all over for improving the bridges between science and policy and the general public. Part of that burden of responsibility is on scientists. It’s in the culture of academia to be conservative, to not be outspoken, and to communicate in the language of science and not in the language of the general public. The way we communicate science is generally through published articles, with statistics and graphics that aren’t easy for the public or politicians to understand. Policy-makers, if you’re going to get to them at all, need a one-page brief in simple language and graphics, which is very difficult for scientists to do in particular because it’s not an easy task to communicate complicated concepts in a single page.

Good data visualization strategies communicate important concepts efficiently. (Graphic by Urban Systems Lab, The New School)

Data visualization is a critical strategy for science communication, and there are a lot of amazing tools there, so we need to train scientists to focus on the communication side of their science as much as the science itself. It’s not something we train for generally, and if anything it’s an afterthought. Focusing on clear and effective science communication including even short sound bites that are nonetheless able to deal with complex science should be a significant portion of what scientists do. The public are now being trained in multiple ways, through the media for example, to digest information in very small bits, and that’s not a traditional way that we communicate science but it’s something we have to get better at.

SB: To wrap things up, what do you think is the most important thing for the public to understand? Or is there a misconception that you’d like to correct?

TM: There are a lot of issues the public needs to understand. Personally, I think a lot about climate change, so I think one of the critical issues is an understanding of what climate change really means. A critical misconception is not understanding that much of the climate changes we will see in the next decades are a result of human impacts that have already occurred, and there is not much we can do to reverse that. We do still have to keep communicating about the human causes and drivers of climate change, and how to shift to a society that is polluting less, but it’s important also to understand that we’re already in the middle of a changing climate, and that much of the changes that are coming are already baked into to the climate system. This means we have to focus on dramatically transforming what we do, if we want to be well-adapted to the kinds of changes that are coming. These changes include for example sea level rise, or increasing heat waves in our cities that are absolutely going to kill more people than they used to, next year and the year after and so on.

Heat kills more people than any other extreme weather event. (NOAA National Weather Service)

We know we’ve built in a certain increase in our mortality rate through heat waves alone, and if we’re going to think seriously about that, and about who’s going to be affected, meaning minorities, the elderly and low-income people, then we have to take climate change seriously at a whole different level. So, part of it isn’t as much a misconception as it is about taking our reality seriously and not seeing it as an “issue” for dinner-table discussion but as fundamental to our whole lives. We are dealing with it but not in a way that we’re doing anything truly transformative at the global scale.

This to me all comes back to the long-term perspective, because we also have to start thinking about what the lives of our children are going to be like twenty or thirty years from now. The rate of change is increasing, and not only change in terms of climate, but also global connectivity is increasing and many rates are getting faster. From social media interaction to the way trades are happening on Wall Street, the rate of change is incredible right now, so that in twenty years we’re going to be in a different world, and we need to prepare for that. We can have some optimism in that sense, because there are a number of amazing things that are happening in terms of new sources of data to analyze and understand this complexity, and new tools and computing processes that can start to do that in real time. Dynamic, fast paced change, positive and negative, is what we live in now.

There’s no stability anymore like we’ve been used to — we’re in the Anthropocene [the current geological age] and we need to take that seriously. Then we can start to deal with what that means in terms of preparing for the next fifty to a hundred years.

(Urban Systems Lab, The New School)

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