The Outdoor Citizen. John Judge
When I visited, I was amazed by the city’s energy, beauty, culture, and abundant humanity. Its architecture is also incredible, with centuries-old stones surrounded by mortar that has been reapplied over the years. The broad, tree-lined boulevards recall European ones, and it has a rich cultural scene. But while the city has a wealth of good qualities, it also has an Achilles heel: it is highly susceptible to natural disasters. Mexico City began as the city of Tenochtitlan, an artificial island built by the Aztecs who dumped soil into the center of Lake Texcoco. After, the Spaniards built Mexico City atop the ruins of Tenochtitlan. Today, Mexico City’s location—sitting on a massive landfilled lake—makes it a prime spot for earthquakes and floods. As you walk around the city, you can see the settling that has occurred at some of the its oldest structures, including government buildings, museums, and cathedrals—testament to past earthquakes and the minimal support the soft bed of Lake Texcoco provides for the city’s buildings. According to the 100 Resilient Cities project:
Mexico City faces significant danger from natural phenomenon. Its geographical conditions make it continually susceptible to seismic hazards, and being located on land that was once a lake makes the city prone to flooding. Runoff from the nearby mountains is improperly managed, which, in addition to flooding, can lead to mudslides and diseases born from standing water.56
Arnoldo Kramer, Mexico City’s chief resilience officer, explains:
Climate change has become the biggest long-term threat to this city’s future. And that’s because it is linked to water, health, air pollution, traffic disruption from floods, housing vulnerability, to landslides—which means we can’t begin to address any of the city’s real problems without facing the climate issue.57
With the help of the 100 Resilient Cities project, Kramer and his team, and Miguel Ángel Mancera, the head of government of Mexico City at the time, developed a strategy to mitigate worst-case scenarios and build resiliency. The government launched a program named Resilient CDMX: Adaptive, Inclusive and Equitable Transformation, and Arnoldo Kramer was appointed its director of resilience. According to the 100 Resilient Cities project, the Resilience Strategy of CDMX was structured around five priorities, described as follows:
1 Regional Coordination: The plan aims to create an institutional strategy for 2030 and promote cross-cutting agenda between institutions.
2 Water Resilience: The main objective is to create a “Water Fund” for Mexico City, develop a culture of responsible consumption, and rescue aquifer zones.
3 Urban and Regional Resilience: This priority seeks to promote the recovery and development of green urban areas, build green infrastructure that can drive hydrologic restoration in iconic public spaces, and provide environmental education.
4 Comprehensive, Safe, and Sustainable Mobility: The aim is to create an integrated public transport system through increasing quality and quantity as well as promoting innovative transport models.
5 Innovation and Adaptive Capacity: The city will seek to drive innovation for integrated risk management.58
Mexico City’s initiatives were incredibly meaningful, just as the ones developed in New York and Rotterdam were, and as cities build their own plans they need to keep in mind their unique landscape, economy, building stock, transportation options, climate, and geographic size. Communities face different challenges, so there is no set formula when it comes to outdoor planning and disaster-prevention planning. But we can take lessons from cities that are already making strides toward long-term sustainability.
Tree Challenges
In the early 1970s, Dutch elm trees were dying by the thousands from Dutch elm disease, a fungus from elm bark beetles that made its way from Europe to the United States. The American elm had been one of the United States’ fastest-growing trees and was commonplace in many towns. In New England and elsewhere, canopies of elm trees blanketed some of the cities’ most beautiful streets. But the very ubiquity of the trees proved fatal. They were planted very close together, and the trees spread the fungus through their tangled underground roots. The decimation was quick and difficult to contain. The first case of Dutch elm disease reported in the United States was in 1928, and the outbreak in the 1970s and 1980s was horrific. To date, it’s estimated that the disease has killed more than forty million American elms.59
My father honored every tree as sacred. When I was a kid, an elm in our backyard contracted the disease. He sent away for a kit that promised to help, and weeks later a large cardboard box arrived in the mail. It contained what looked like a hundred tubes and other pieces to assemble a Rube Goldberg machine. We drilled holes around the circumference of the base of the trunk of the diseased tree and then inserted clear tubes into it through a pressurized pump in the root-flared system. I was tasked with pumping the fungicide serum into the tree root three times a day. I’m not sure if the tree is alive today, but it definitely lived beyond the time we moved from that home years later. The experience instilled in me an appreciation for trees and a fierce desire to protect them, like my father had.
The loss of the forty million American elms remains memorable for arborists, tree wardens, and parks supervisors who are in their late forties or older. It’s important to share this history of Dutch elm disease to show how quickly the health and survival of valuable natural assets can be endangered. Today, elms are hatching a return and making a healthy comeback in many cities. Hybrid elms, which have been crossbred to incorporate the genes of other plants, are more resistant to Dutch elm disease. But other trees are in danger, particularly urban ones.
For urban trees, challenges abound, from the encroachment of overdevelopment to the toxicity of soil to neglect and vandalism. Urban trees and other city-based species live a fraction of the lifespan of their rural counterparts. One study suggested that downtown trees have an average lifespan of seven years, compared to thirty-two for suburban; another suggested thirteen years for downtown trees, thirty-seven for residential, and 150 for rural.60
Nadine Galle and her organization, Green City Watch, work to determine forest cover and tree strength in urban areas, and she told me that they utilize geospatial data and artificial intelligence to inform their findings. Their research has shown that many urban areas have cut back on forest cover, which has led to more fragile ecosystems. A report in the journal Urban Forestry & Urban Greening confirmed the loss, showing that between 2009 and 2014, US urban tree coverage fell from 40.4 percent to 39.4 percent, an annual “urban/community tree cover loss” of 175,000 acres, or 36 million trees. This resulted in an estimated benefits loss of $96 million per year—a dollar cost translated from the capacity of trees to remove air pollution, sequester carbon, conserve energy by shading buildings, and reduce power-plant emissions.61
To counter urban tree loss, a number of cities have undertaken Million Tree Initiatives to add one million trees to their cities through planting and the giving away of free trees. In 2005, Los Angeles Mayor Antonio Villaraigosa planted a tree his second day in office and announced a plan, Million Trees LA, to plant one million trees in Los Angeles. When he left office eight years later, more than 400,000 trees had been planted.62 Since then, City Plants has taken over the initiative. City Plants was already a partner of the Los Angeles Department of Water and Power, which had launched a program called Trees for a Green LA in 2001, and today, in collaboration with six nonprofits and several city departments, City Plants plants and distributes twenty thousand trees each year.63 Denver, Boston, Shangai, London, Ontario, and other cities have their own initiatives. Incredibly, Ethiopia planted more than 350 million trees in a twelve-hour period in June 2019, a world record, made possible by millions of Ethiopians who took part in a challenge that was a part of Prime Minister Abiy Ahmed’s Green Legacy Campaign.
The only city in the US to have reached its goal to plan one million trees is New York City as part of its Million Trees NYC campaign. The campaign came about when then-mayor Michael Bloomberg and New York Restoration Project (NYRP) Founder Bette Midler were viewing six hundred blossoming cherry trees along the Harlem and Hudson rivers that NYRP had planted. It’s said that “Bette turned to the Mayor and said ‘why should we stop here? We should plant one million!’”64 At the time, no other city had achieved this, but the city achieved its objective through three strategies:65 1. Giving away trees to private homeowners in areas with especially