Our cities need to capture carbon, not just offset it

Climate Emergency

One clear solution to biodiversity loss and climate change is to integrate green spaces into urban buildings, as well as between them, as they have done successfully in Singapore.

As more and more of us move into urban areas, the impact of cities on biodiversity loss and climate change becomes more severe.

One way to reduce this impact would be switching the way we build from an approach that merely reduces carbon emissions to one that actively captures carbon from the atmosphere along with achieving net-zero carbon targets.

By 2050, 68 percent of the world’s population is expected to reside in urban areas. Accommodating these people likely means more homes, more public buildings, and more roads – an increasing urban sprawl that leads to deforestation and the loss of green habitats.

As well as putting plant and animal species at risk of extinction, this loss of green space directly contributes to climate change because plants, particularly trees, are vital to capturing carbon from the atmosphere.

To make matters worse, biodiversity loss and climate change are tightly linked – when one gets worse, the other does too, creating an increasing spiral of ecological and climatic problems to grapple with.

According to Environment Aotearoa 2019, only a third of New Zealand’s native forest remains (mainly in mountainous and hilly areas) and nearly 4000 species are threatened or at risk of becoming extinct. If we do not conserve and regenerate the habitats and conditions these species require, we will continue to face the consequences of biodiversity loss, which range from decreased resilience to flooding, loss of food sources, increased disease, poor air quality and many more.

The creation of new infrastructure for growing urban areas is a major cause of much of the biodiversity loss and climate change impacts we have experienced so far. For example, removing vegetation to make way for buildings can cause erosion, building new roads can disrupt or destroy the ecosystems of native species, and ill-planned increased density can lead to increased use of air-conditioning, which contributes to climate change.

However, I believe our built environments can also be the solution to many of our struggles with biodiversity loss and climate change.

One of the biggest problems with urban development is that it creates habitat fragmentation, leaving cities with several small and disconnected green spaces, rather than the large and connected habitats that urban biodiversity needs. One clear solution for this is to integrate green spaces into urban buildings, as well as between them, as strategically planned green spaces have significant potential to conserve biodiversity while capturing and storing atmospheric carbon.

There are several options for integrating green spaces and vegetation into new and existing buildings and urban areas in general. These range from including internal vegetated courtyards in building designs and planting indoor gardens to planting directly on the walls and roofs of buildings.

Using native plants in these green spaces is particularly important for reducing biodiversity loss in the context of Aotearoa, as is selecting plants that can efficiently capture carbon from the atmosphere.

A leading example of creating green urban environments can be found in Singapore. There, biodiversity conservation and climate change mitigation strategies are embedded into policy frameworks, with an overarching “City in a Garden” ethos that involves greening the whole city, including buildings.

Between 1986 and 2010, these policies increased Singapore’s green coverage from 36 percent to 56 percent, despite massive increases in population and urban growth. As well as capturing carbon, these green spaces improve air quality, reduce storm water problems, contribute positively to the mental and physical health of residents, and increase workplace productivity.

My current research involves surveying and interviewing built-environment professionals and ecologists here and around the world about their views and approaches to mitigating climate change and biodiversity loss. My initial findings show most professionals focus on emissions reduction or investing in carbon offsetting. These strategies are vital to managing climate change and biodiversity loss, as is using building materials that store carbon (such as timber).

But these strategies do not actively pull carbon from the atmosphere. Instead of paying for carbon or biodiversity offsets, the building industry can employ strategies for active carbon capture and the enhancement of biodiversity through integrating vegetation and green spaces more effectively into or onto or around buildings, improving existing sustainable strategies.

I intend to translate the scientific study of biodiversity and carbon capture into industry-focused guidance that helps building professionals think about the benefits of biodiversity and carbon sequestration and provides examples of proven strategies.

In this era of climate emergency and biodiversity crisis, built-environment professionals have a unique opportunity to address these interlinked complex issues in a radically more sustainable way. Let’s not just think about regenerative buildings, let’s build them.

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