Urban rooftop gardening can be a solution to the climate crisis
The urban population in Bangladesh is predicted to rise 46% by 2030 and 58% by 2050 (CPD, 2020) with worsening climatic events. In urban areas, rooftops are mostly abundant and underused resources for the city and are mainly used for drying clothes. The Ministry of Agriculture’s agriculture information service Dhaka stated that about 450,000 roofs cover around 4,500 hectares of space.
In this case, urban rooftop gardens can be considered as an urban Nature-based Solution (NbS). NbS fosters methodical approaches for social, environmental, and economic challenges by restoring, and safeguarding the ecosystem and causing sustainable urbanization.
For a densely populated city like Dhaka, rooftop gardens can be an instrumental NbS to tackle climate change. Rooftop gardening can enhance food security and nutrition in urban and peri-urban areas by meeting part of Dhaka city's growing population's demand for fruits and vegetables.
Rooftop gardening also encompasses social benefits by fabricating spaces for recreational benefits and creates job opportunities. Most importantly, it provides environmental benefits to urban infrastructure by acting as insulators to cool down the temperature of buildings by absorbing heat, and minimizing the need for air-conditioning. It also improves air quality by producing oxygen and acts as a carbon sink to adapt and mitigate the impacts of climate change.
Additionally, rooftop gardens can promote innovation by encouraging the diversion towards a circular economy-based Nature-based Solutions approach. This can substantially contribute to climate change mitigation by ameliorating sustainable material management and decarbonisation.
Circular Nature-based Solution can increase the resilience of the ecosystem through reuse, reduce, recycle, remanufacture and repurpose strategies. These lead to the closure of material and energy loops and terminate waste generation. Nature-based Solution entails the circularity concept, for example, it understands that inedible food by-products and human waste have phosphorus and nitrogen which can be used as inputs for producing something new.
For instance, rooftop gardens can be a destination for food waste, which can be converted into organic fertiliser and boost plants’ growth. This minimizes the usage of potentially harmful chemical fertilisers and can help in waste management issues. Dhaka North and South City Corporation can conduct consultations with private companies to establish fertilisers made from urban organic waste to peri-urban farms to support local food sourcing.
Rooftop gardening is mainly traditional gardening, vertical gardening, and hydroponics, etc. Traditional gardening involves producing fruits, vegetables, medicinal plants, herbs and spices utilizing flowerpots, planter boxes, plastic or metal drums.
At the same time, vertical gardening is a way of growing vegetables on vertical surfaces and can be done in small rooftop spaces with minimal investment than traditional gardening. On the other hand, hydroponics is the cultivation of vegetables without soil, using water and a plant nutrient solution. It needs consistent monitoring to ensure that accurate chemical balance is maintained. Hydroponics requires less space
A real challenge, which is the lack of awareness raising and know-how platforms, can hinder the process. Therefore, it is crucial to establish physical community centres or platforms that can be community governed to offer accessible knowledge about inputs (ie, seeds, seedlings, saplings, suitable plant species and fertilisers) and support implementing urban Nature-based Solution, as rooftop gardening.
Youth, existing private sector players in gardening such as Prakriti, Nagarkrishi, and Green Savers, schools, universities, urban city planners, engineers, practitioners, NGOs, Civil Societies, local governments can be key players in establishing this centre. Real estate companies can raise the landowners' awareness of the benefits of rooftop gardening and make the roofs waterproof (apply polyester built-up systems, fluid applied membranes, concrete admixture) to refrain the roofs from getting damp. Some households might find it expensive to eliminate this hindrance.
Dhaka North and South City Corporation and local municipalities can collaboratively set up a financial scheme providing citizens with grants up to 80-100% of the upfront cost of urban agriculture projects. Citizens who desire to experiment with agriculture practices in their rooftops and self-owned spaces can apply for it.
Nonetheless, the government of Bangladesh has established a policy to motivate homeowners to utilize their rooftops for gardening and planting trees and plants. On March 2021, the Honourable Minister Tajul Islam, Ministry of Local Government, Rural Development & Co-operatives (LGRD), declared that the government will provide a 10% holding tax rebate to city residents who practices rooftop gardening.
Hence, it will be crucial to raise awareness on this policy and inspire citizens to build their own rooftop gardens to reduce the impacts of climate change. A monitoring framework of the tax rebate policy will be vital to document the lessons learnt and track the benefits and constraints of urban nature-based solutions.
Afsara Binte Mirza is working in the International Centre for Climate Change and Development as a Junior Research Officer. Her research interest lies in Nature-based Solutions, National Adaptation Plans and Gender Equality. Afsara can be reached at [email protected]