Making cities embrace climate change

With summer setting in, buildings tailored to regional weather — and green corridors — can help urban landscapes tackle the heat challenge

February 23, 2024 03:56 pm | Updated 04:42 pm IST

In 2020, the world experienced the hottest September on record. Fast forward to 2023, this scorching reality intensified, with NASA ranking 2022 as the fifth warmest year, with the hottest September ever documented in 174 years. What awaits us in 2024 is yet to be seen even as summer begins in most parts of India.

Densely populated urban cores are increasingly subjected to rising temperatures, forming urban heat islands. With over two-thirds of the global population predicted to live in cities by 2050, urban areas will experience heatwaves more intensely than their rural counterparts.

Oxfam International recently reported that Dharavi, one of the most densely populated slums globally, registered temperatures over 6 degrees hotter than the rest of Mumbai.

The design, or lack thereof, in urban spaces contributes significantly to this heat challenge. Extensive stretches of exposed asphalt, common in car-centric urban layouts, along with concrete-clad buildings and sidewalks, absorb heat throughout the day and release it at night. Similarly, massive glass facades create a greenhouse effect, trapping heat within the buildings. The prevalent use of inefficient localised cooling devices, such as air-conditioners, not only consumes substantial energy but also releases additional heat into the external environment.

In response to these challenges, over the past decade, governments, urban development agencies, and various stakeholders have recognised the necessity of sensitively responding to record-breaking temperatures. But, despite significant strides, the global heatwave warnings this summer underscore the imperative to reevaluate current urban design methodologies. It prompts a reconsideration of the fundamental principles of ecological landscape urbanism, emphasising adaptability, scalability, and ease of replication at individual or community levels, all while fostering substantial ecological benefits.

A cyclical process

In the last two million years, global warming has occurred on multiple occasions, typically taking around 5,000 years for the planet to warm by 5 degrees. However, the striking statistic is that in the past century alone, the temperature has risen by 0.7 degrees Celsius, a rate approximately 10 times faster than the average pace of warming during ice-age-recovery. Projections for the next century indicate a predicted rate of warming at least 20 times faster than the historical norm, marking an exceptionally unusual and rapid rate of change.

Most cultures are anchored around fostering a lifestyle harmonious with nature’s rhythms with minimally invasive everyday rituals. The bodhi tree beneath which Buddha attained enlightenment, and the baobab tree, revered as the tree of life in ancient African cultures, exemplify the spiritual connections attributed to trees. European cultures, too, find sacredness in oak trees, while Native Americans intuitively acknowledge the correlation between our well-being and the health of the trees surrounding us. In the Rig Veda, trees and plants are revered as conscious divine living beings. The specifically designates trees as agents capable of purifying and eliminating pollution.

Post-industrialisation, the human footprint has expanded rapidly, significantly contributing to systemic land changes, severely altering the environment in some parts of the world. Cities that were earlier the prime hubs of growth, like Rio de Janeiro and New Delhi, now witness the adverse consequences of human actions without the means to reverse them. Learning from the past approaches, contemporary society should seek to design cities that align with the rhythms and cycles of nature. It is time we acknowledge the interconnectedness of human activities with the environment and have this harmony reflected in urban development.

Reflecting harmony

Historically, adaptations to varying climates had a deep-rooted understanding of the materials shaping the construction of settlements. Recognising that certain building materials absorb, radiate, or transform heat allowed vernacular practices to tailor urban constructions to regional climates. However, contemporary urban cores often adopt a one-size-fits-all approach, employing materials like glass, concrete, and asphalt regardless of contextual relevance.

Yet, worldwide, there are compelling examples of innovative adaptations to extreme climatic conditions. The Ahmedabad Heat Action Plan introduced a cool roof initiative for informal settlements, lowering indoor temperatures by painting roofs white, a colour that reflects 60% more heat than grey. According to the United Nations Environment Programme, Singapore’s application of light-coloured reflective paints on building roofs has shown promise in reducing ambient temperatures by up to 3.5 degrees Fahrenheit. A similar initiative in New York City, covering over 10 million sq.ft. of rooftops with reflective paints since 2009, has effectively reduced the need for air-conditioning and the associated waste heat.

Manhattan Waterfront Greenway Corridor

Manhattan Waterfront Greenway Corridor | Photo Credit: Getty Images/istock

Green corridors, another impactful strategy, have demonstrated their efficacy in mitigating rising temperatures. Examples include the Manhattan Waterfront Greenway Corridor, the interconnected network of greenery called ‘Corredores Verdes’ in Medellin and the Cheonggyecheon in Seoul, and the Madrid Rio Corridor. These ecological corridors not only lower temperatures but also serve as essential sinks for excess carbon in the atmosphere, capturing carbon dioxide and producing pure atmospheric oxygen. They facilitate groundwater infiltration, benefiting local watersheds and contributing to the overall global water cycle. These green corridors also have the potential to remediate pollutants that have leached into the soil. To fully leverage trees as regulators of climate stress, cities must treat them as essential infrastructure, ensuring their health and effectiveness. Although this incurs a cost, it pales in comparison to what cities spend on other environmental protections.

Cheonggyecheon, in Seoul.

Cheonggyecheon, in Seoul. | Photo Credit: Getty Images/istock

At the community level

Individuals, communities, landscape architects, urban designers, and policymakers can all play pivotal roles in advocating for the planting of native trees, promoting biodiversity, and enriching the local flora and fauna. Schools and parents can instill environmental consciousness in children by encouraging tree planting and care, fostering a connection with nature for a better environment now and for generations to come.

Landscape architects and designers can integrate solar analysis into their projects, ensuring the incorporation of 6-8 shade trees in each design. Policymakers can contribute by offering tax incentives to residents with large shade trees, providing shade to public areas. Certain countries incentivise alternative climate adaptation methods, and some jurisdictions strictly regulate tree removal, requiring mitigation and replacement to maintain or increase canopy coverage. When this approach is scaled and replicated across entire communities, it results in lower temperatures, reduced energy costs, and the establishment of shaded zones for people to find respite.

The writer is Principal, Studio Arth.

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