Improve urban waste management and transition to zero-waste cities

In 2023, more than half of the world’s population lived in cities, and urbanization is accelerating especially in developing countries. Coupled with growing income levels and increased consumerism, global waste generation rates are expected to grow at twice the rate of population growth between now and 2050. If these trends continue, global solid-waste-related emissions will increase from 1.6 billion tonnes of carbon dioxide equivalent (CO2e) in 2023 to 2.6. billion tons of CO2e by 2050 unless effective zero-waste policies and programs are implemented.

Domestic waste is high in organic matter from food and animal waste, as well as sludge, sullage, textiles and paper — all of which emit methane, a gas with 26 times the potency of CO2. Non-biodegradable wastes (notably in the form of construction wastes, plastics, metal, aluminum canes, tires, most chemicals and polystyrene fibers) do not degrade over time unless recycled or reused.

Achieving zero-waste outcomes will require shifts in the way biodegradable (organic) and non-biodegradable (inorganic) components are managed. Effective zero-waste programs promote circularity and reduction in resource usage instead of the linear-economy paradigm of “extract-produce-discard.” Transitioning to and maintaining zero-waste outcomes presents a win-win situation for cities, enabling them to contribute to climate mitigation while also offering citizens and regional ecosystems cleaner and healthier living environments.

Currently in developing countries, only some of these inorganic wastes can be reused in construction and the building of roads; the rest of them get deposited in dumpsites, burned or dumped into waterways. Simultaneously, electronic wastes (e-wastes) contain potentially toxic chemicals, and huge quantities of plastics get transported through waterways to the oceans, choking riverine and marine organisms. Harmful microplastics are now a part of the human food chain.

Achieving zero-waste outcomes can cause a myriad of benefits at the local, regional and global levels: local residents benefit from clean streets and healthy neighborhoods and waterways; regional ecosystems benefit from reduced stress and pollution; and the global economy benefits from the elimination of harmful impacts caused by uncontrolled greenhouse gas emissions, notably methane.

While the cities system is linked with the concept of circularity, the focus of circularity on organic waste is still a nascent area of study, with most research currently centered on inorganic waste (such as plastics, paper, glass, and other materials).