Anyone who walks during the summer in a city like Boston knows that a significant amount of time is spent charting routes with shade. But I can’t use that as my only excuse for being off-task. Honestly, I’m distracted. The swirling headlines of the U.S. presidential election, an unprecedented UN climate conference looming, and the phrase “decade of decisive action” weighs heavy on my shoulders. While it’s easy to get caught up in current events, those of us with solutions must stay focused.
A perhaps helpful Japanese phrase to call upon is “kotsu kotsu,” essentially meaning to slow down and focus on the task at hand, and do it well. Temperatures are soaring, people are suffering. As a recent UN COP letter stated, “time lost is lives, livelihoods, and the planet lost.” Cooling our cities and communities is more important than ever.
As landscape architects, we constantly hear of the challenges associated with planting enough trees, but some cities have figured out ways to rise above while also reducing greenhouse gas emissions.
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The 2017-2037 Master Plan for Barcelona is directing efforts to cover 30 percent of the city in trees by 2037.
Part of their “Trees for Life” strategy includes giving roots more room. Providing larger tree wells for individual trees and expanded tree planting areas to increase connectivity reduces the need for irrigation and increases drought resistance.
Per their guidance, the tree well opening size should be the eventual mature tree canopy diameter – not the canopy size on installation day. More native and heat-tolerant species are being added to establish long-term plant communities throughout the city. These are installed, watered, fertilized, and monitored by the city.
Paris has been planning to cool this year’s Olympic visitors for some time. This work started with the Landmark Urban Forest Project in 2019, which has become even more important since the deaths of 11,000 people during the 2022 summer heat wave in France. Over the course of five years, nearly 40,000 trees have been planted in the urban environment thanks to the City Forestry Service.
The transformation of Paris’ Place de Catalunya deserves recognition. Deprived of vegetation and composed primarily of paved surfaces, the place was not only hot, but also full of noise and air pollution. Today, it is home to 470 trees, which cover 60 percent of the site. There are over 5,000 square meters of permeable surfaces. More than half of rainwater is managed by swales. And the city estimates 4 degrees Celsius of cooling for its surroundings.
Creative Cooling
But what do we do when there is little to no rainfall? It’s intriguing to consider how we might harness the concept of micro-water harvesting to support our cooling ambitions.
A demonstration garden called Becoming Xerophile by Cooking Sections at the Sharjah Architecture Triennial in the United Arab Emirates shows how creating landforms can channel very small amounts of rainfall – enough to support drought-tolerant, arid tree species without extra irrigation.
The nine sand bowls were created to prove the concept of waterless gardens, using plants that can grow in very dry environments called xerophiles. The bowl shape creates microclimates, an approach used for centuries in arid places.
Another approach is to collect and use moisture in the air. In Peru, the Fog Water Farm Park and Gardens by Traction responds to water scarcity by taking advantage of the fog belt that is present six to nine months out of the year. Fog moisture is collected by simple fabric and timber structures and stored in cisterns to supply community gardens.
Taking Action
These may all seem like simple things, but they require a suite of contributors to implement. Landscape architects can’t do this alone – we need the support of planners, policymakers, engineers, architects, developers, homeowners, and so many more. These are simple, cost-effective, nature-based strategies. When implemented successfully, they provide environmental, social, and economic benefits.
There are some incredible resources to explore. The recent ASLA study Landscape Architecture Solutions to Extreme Heat by Dr. Daniella Hirschfeld, ASLA, PhD, highlights four key strategies to reduce heat, including:
- Increasing trees
- Providing shade
- Using less hardscape
- And increasing groundcover
The Landscape Architecture Foundation showcases examples that are Beating the Heat as well as a study on the most efficient landscapes for cooling air temperature. And be sure to check out Atlas Lab’s very cool new Cool-Kit, created by 2024 LAF Fellow Kimberly Garza, ASLA.
We’ll be including cooling metrics into the Climate Positive Design Pathfinder app in the fall release, so stay tuned for that. In the meantime, stay cool, focus, and keep going.
This article was originally published on The Dirt.
