Greening Cities: An Adaptive Solution to Climate Change
The impact of climate change is, quite literally, all over the map. Given all the uncertainty, how can we best plan to build our infrastructure?
Imagine being tasked with designing new infrastructure to protect a community that's projected to experience sea level rise in a range anywhere from 6 inches to over 6 feet during the 21st century. And how will we factor wildly varying regional differences? For example, higher temperatures projected for the interior of the country than the east or west, or higher sea level rises along the coast of Louisiana than along the coast of Oregon.
"Imagine being tasked with designing new infrastructure to protect a community that’s projected to experience sea level rise in a range anywhere from 6 inches to over 6 feet during the 21st century."
To manage the uncertainty of future climate impacts, we need to turn to "distributed" (or neighborhood scale) infrastructure approaches. Unlike traditional, centralized approaches (a power plant or a large water supply reservoir, for example), distributed infrastructure consists of myriad small components -- all working together, such as solar panels or rainwater harvesting and water recycling systems, etc. The benefit of distributed infrastructure systems is that they can evolve over space and time. Individual components can be added or replaced; technological advances can be incorporated. Capital investments can be spread over multiple years, if not decades.
One form of distributed infrastructure that holds great promise is urban green infrastructure. This includes networks of green space, including natural areas such as woodlands, built areas such as parks and community gardens, and engineered interventions such as green roofs, rain-gardens, bioswales (shallow, vegetated depressions in city sidewalks), and other green designs.
"To manage the uncertainty of future climate impacts, we need to turn to 'distributed' (or neighborhood scale) infrastructure approaches."
For the past 15 years, I've been part of an interdisciplinary team of researchers, along with colleagues from the government and private sector, that has explored the performance of urban green infrastructure systems. Intriguingly, we've learned through surveys that people value urban green spaces for their social and cultural benefits -- even more than for environmental benefits. So, strategies for climate adaptation that provide immediate, tangible benefits to people are more likely to be embraced by the community and gain momentum than those that don't. This important connection that human health and wellbeing has to green spaces should be prioritized in planning green infrastructure.
Neighborhood-scale green infrastructure is a very good investment, because it can grow and evolve with time. Green spaces can soak up rainfall, protecting our cities against the devastation and disruption of frequent flooding. This is a far better strategy than trying to design massive underground water collection systems, since we have no idea how large those would need to be. Green spaces can also help cool our cities as temperatures rise, whereas centralized structures can't.
"Neighborhood-scale green infrastructure is a very good investment ... Green spaces can soak up rainfall, protecting our cities against the devastation and disruption of frequent flooding … also help cool our cities as temperatures rise…"
In addition, present urban green infrastructure plans are primarily developed by local municipalities and approached with little unification from city to city. While there is national and global dialogue on climate mitigation techniques, there is little conversation about climate adaptation. As such, those communities with the fewest resources -- also those most often vulnerable to climate impacts -- are left with little information and no support.
To realize the potential of greening our cities as a strategy for climate adaptation, we need to:
- Foster the exchange of green infrastructure knowledge among cities of all sizes. A great start would be to establish a government-led national database of local evidence-based urban adaptation policies and strategies. This will enable cities, especially those with smaller budgets and few resources, to draw on existing solutions and adjust them for their own contexts.
- Prioritize public preferences for green infrastructure in program design, including vegetation choices. The way people feel about their green environment, and interact with it, significantly affects the performance of the program and its components. For example, a vandalized bioswale where the vegetation has been removed or damaged, does not perform well. A well stewarded and cared for bioswale, does.
- Integrate operation and maintenance needs and budgets in green infrastructure programs right from the start. Like all distributed infrastructure systems, operation and maintenance requirements are spread across a large number of components. In the case of New York City, for example, to operate and maintain thousands of individual green elements means considerable costs. If not accounted for, such costs can stretch city budgets and services. We are already underinvesting in infrastructure maintenance, and we should not repeat or pile on to this existing mistake.
- Invest in the monitoring individual green infrastructure and big data analysis to continue to spur innovation. To understand how well distributed systems are performing requires knowledge of how each component behaves and contributes to system behavior. This investment will require advances in low-power and low-cost sensors, wireless communications, and data science techniques.
Climate adaptation is a moving target, which is why distributed green infrastructure solutions make so much sense, especially in our cities. By investing in urban green spaces and design, we’re supporting the health and well-being of residents while also helping to secure the habitability of our urban centers now and into the future.