Achieving sustainable urban growth on a global scale

From the impacts on the environment and climate to transforming land cover and habitats, urban growth is driving global change. Urban areas contribute up to 75% of global greenhouse gas emissions. By 2050, urban areas globally will either double or triple, and the raw materials needed to build future cities is more than the world can sustainably provide.

Yet, the impacts of cities on Earth systems are not factored into policy and planning among international agencies and that needs to change, says Karen Seto, Frederick C. Hixon Professor of Geography and Urbanization Science at the Yale School of the Environment. In a commentary recently published in Science, Seto and an international group of leading scientists called for the creation of a new urban advisory system.

Noting that more than half the world’s population live in urban areas and worldwide urban land expansion is one of the key drivers of habitat and biodiversity loss, the authors point to myriad ways that urban expansion affects global systems by putting pressure on resources, ecosystems, and the climate and emphasize the importance of scientific research in local and global decision making.

The authors advocate for the creation of an urban science panel that could support the United Nations as well as multilateral policy-making groups.

“This is about ensuring that world leaders and policymakers have the information that they need at their fingertips to design a world that reflects and responds to humanity’s urban future,” the authors wrote.

Seto, director of the Hixon Center for Urban Sustainability, is one of the world’s foremost experts on the global impacts of urbanization. She was the coordinating lead author for two U.N. climate assessment reports, the IPCC 5th (2014) and 6th (2022), and co-led the chapters on how cities can mitigate climate change. She pioneered the use of satellite remote sensing analysis to study land change and urban growth and has focused her research on how cities can play a significant role in mitigating climate change through design, low-cost energy initiatives, and sustainable transportation and building materials. To accomplish this, a coordinated effort is needed to transform existing urban science into practical guidance for international policy design for urban areas, Seto and co-authors Jessica Espey, Michael Keith, Susan Parnell, and Tim Schwanen noted.

“Cities are the nucleus from which humanities’ impact on all Earth systems can be observed. One would thus expect urban dynamics and impacts to be at the top of global governance agendas,” they wrote in the commentary.

There are existing bodies that work on cities and sustainable development goals within the U.N. and regulatory bodies within states, cities, and towns that work at the local level, but the authors stress that their focus is on singular issues or local regulations rather than at the planetary level.

“Although these existing parallel processes are important, they are failing to bring the seismic effects of urban change on the world to the attention of policy makers,” they contend.

They recommend the creation of an urban science advisory panel composed of scientists who have a clear political mandate and a requirement to submit findings to the U.N. Such a group could be rooted in an entity affiliated with the office of the U.N. secretary general or as part of the U.N.’s Multi-Stakeholder Forum on Science, Technology and Innovation for Sustainable Development Goals.

“Whatever mechanism is used, it is well past time for evidence-based dialogue on the planet-wide effects of urbanization at the highest levels of international government. Our planet’s future is an urban future, and our systems of international administration must reflect that,” the authors state.