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Can future cities store as much carbon as forests?

When cities expand, they usually encroach on forested areas and agricultural land, thus “consuming” carbon sinks. This makes it harder for municipalities and countries to reach the net-zero emission targets that are essential to avoid a climate catastrophe. 

Recently, a team of researchers from Aalto University in Finland has developed a new metric called the “carbon storage (CS) factor,” which reflects how much carbon can be captured in planned urban developments, and may thus help urban planners keep urban growth in line with emission targets.

By comparing the amount of carbon storage capacity lost – for instance, from deforestation – with the CS factor of urban development plans which use different methods and technologies, planners could make sure that development maintains or even restores a specific region’s natural carbon storage capacity.

“There are many tools available to increase the CS factor. Increasing wooden construction is a good option in some regions, but it’s also possible to store carbon in the soil using biochar and other tools, or to include new fast-growing plants in the landscape, or even through direct carbon capture and storage technologies. We hope planners will adopt this mindset and use the CS factor to help them plan sustainable urban growth,” explained senior author Seppo Junnila, a professor of Real Estate Business at Aalto.

As a case study, the experts used the CS factor to assess how wooden construction in Finland’s capital region could compensate for deforestation from urban growth.

The analysis revealed that, by using the right type of wooden construction technologies, as much as 70 percent of future development could preserve the lost forest’s carbon storage capacity. However, this would require the use of materials that can store substantial amounts of carbon, such as log or cross-laminated timber.

While similar results could be obtained using wooden construction elsewhere in Europe, Asia, or even Oceania, increased wooden construction can be a sustainable method only if forests are sustainably managed.

“Our goal isn’t to encourage cities to expand into new areas but to provide planners with tools to mitigate the impact of development on carbon storage when forest clearing is unavoidable,” Junnila concluded.

The study is published in the journal Environmental Research Letters.

Green cities of the future

Green cities of the future will be designed to minimize their environmental impact while promoting the well-being of their inhabitants. These cities will incorporate a wide range of sustainable practices and innovative technologies to address challenges such as climate change, resource scarcity, and urban sprawl. 

Key features of green cities of the future may include:

Renewable energy

Green cities will rely heavily on renewable energy sources like solar, wind, hydro, and geothermal power. This will help reduce their carbon footprint and contribute to a cleaner environment.

Green transportation

Public transportation systems will be prioritized, featuring electric buses, trains, and trams. Bike lanes and pedestrian walkways will be widespread to encourage walking and cycling, while electric vehicle charging stations will be readily available.

Sustainable architecture

Buildings will be designed for energy efficiency, utilizing green roofs, solar panels, and advanced insulation materials. Vertical gardens and urban farming will be integrated into the cityscape to enhance biodiversity and local food production.

Waste management

Cities will employ comprehensive recycling and composting programs to minimize waste. Advanced waste-to-energy technologies will be used to convert non-recyclable waste into energy, reducing landfill usage.

Smart city technology

IoT sensors and data analytics will be used to optimize energy and water consumption, monitor air quality, and improve waste management. Autonomous vehicles, drones, and robots may also be utilized to enhance public services and reduce human intervention.

Green spaces

Urban parks, gardens, and other green spaces will be abundant, providing habitats for local wildlife and promoting physical and mental well-being for residents.

Water conservation

Green cities will employ innovative water management practices, such as rainwater harvesting, permeable pavement, and greywater recycling, to reduce water consumption and minimize runoff pollution.

Climate resilience

Urban planning will prioritize climate adaptation measures, such as flood barriers, stormwater management systems, and heat island mitigation strategies, to protect the city and its inhabitants from the impacts of climate change.

Circular economy

Green cities will encourage the reuse and recycling of materials, fostering a local circular economy that reduces waste and promotes sustainability.

Community engagement

Residents will be encouraged to participate in decision-making processes and contribute to local sustainability initiatives, fostering a sense of ownership and responsibility for the city’s environmental performance.


By Andrei Ionescu, Staff Writer

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