Satellite and Sponge Cities for Vulnerable World Metropolises: Renewed Urban Climate Adaptation
By Daria Kurushina
Introduction
It is projected that by 2050, over 800 million people in 570 cities could be subjected to more than half a meter of sea level rise. Sea level rise affecting the biggest coastal cities, which are often major capitals and financial hubs, could cause a severe global GDP slump. Post-flooding settlement and reconstruction, in addition to knock-on impacts on critical infrastructure, energy plants, power grids, urban transportation systems, and valuable properties, could account for $1 trillion by 2050 and $14.2 trillion by 2100 in economic losses.
Stalled and insufficient measures to limit global temperature rise to 1.5 °C above pre-industrial levels expose coastal urban populations to the harms of climate change. While countries are hesitant to admit defeat on a Paris Agreement goal, pledging more investment and policies in curbing greenhouse gas emissions annually at the COP, sustaining sea-level rise and limiting hazardous weather patterns is not feasible. Proactive adaptation would galvanize the emergency response needed to avoid losing coastal cities and their economic and cultural contributions. Doubling down on urban climate adaptation, introducing innovations such as sponge cities, relocating the most vulnerable capitals and financial centers, and building satellite cities in less-disaster-prone areas are just some important, if also costly, preparedness measures countries should start taking right away.
Capital Relocation and Satellite Cities
Historically, capital cities have been relocated due to issues of overcrowding, congestion, and administrative needs. But now, we need to establish climate change as a primary impetus for urban rejuvenation and major city relocation. Brazil, Turkey, Nigeria, Côte d'Ivoire, Australia, and other countries relocated capital cities for administrative and congestion-related reasons in the 20th century. In Egypt, South Korea, and Malaysia, initiatives are currently underway to establish new capital centers. In some cases, the reasoning is to alleviate the economic and social pressure caused by overcrowded cities; in others, the point is to provide new financial and administrative hubs.
Although urban decentralization to disperse infrastructure and industrial facilities to remote regions has historically been the primary motivation behind shifting capital cities, the current trend is increasingly influenced by the looming threat of climate change. In Jakarta, the world’s fastest-sinking megacity, 40% of the city landscape is below sea level. The Indonesian government announced plans to relocate its capital from Jakarta to East Kalimantan by 2045 and create a green net-zero metropolis, simultaneously spending billions of dollars to prevent land submergence in Jakarta. Similarly, the Philippines designated New Clark City as an alternative administrative center to disaster-prone Manila. Future-oriented city planning that considers scientific projections of intensified climate-driven disasters, as evidenced in the Philippines or Indonesia, addresses multiple challenges simultaneously.
In Asia, most financial centers and capitals are near the coastline. The continent has long grappled with the devastating impacts of typhoons and sinking. Responses have included disaster risk reduction and the creation of satellite inland cities. However, other regions are taking a slower approach, relying on their lower vulnerability to disasters while aggravating climate risks through inaction. The recent devastating floods in cities like New York, Dubai, and London, coupled with heatwaves across Europe and earthquakes in Turkey and Morocco, underscore the urgency for proactive measures. Asia showcases the innovative metropolitan initiatives that can be adapted to other global metropolises.
Spotlight on Sponge Cities
China has been leading the Sponge City initiative in disaster-prone provinces since 2015, seeking to develop a holistic strategy for urban rejuvenation and adaptation. China has invested more than $140 billion in addressing the dual challenges of drought and flash flooding by integrating “sponginess” and absorbing features, rainfall infiltration, enhanced water management, and flooding control into 90 cities across 13 provinces, including flood-prone Beijing, Tianjin, Shanghai, Guangzhou, and Shenzhen, among others. This novel strategy spread globally, with the biggest world capitals leveraging the “sponginess” of the Chinese initiative to integrate ecosystem-based adaptation for flood reduction. However, challenges persist, as demonstrated by the 2023-2024 severe flooding in Hebei, Fujian, and Guangdong provinces. Despite high expectations, a decade of rushed construction, and extensive investment, the Sponge City disaster reduction measures have not kept up with the speed of climate-driven vulnerability and subsidence. These incidents underscore the need for alternative climate risk adaptation strategies, including robust disaster preparedness plans and, possibly, evacuating heavily inhabited areas to higher elevated satellite cities.
Climate adaptation initiatives like China’s sponge cities, as well as other measures like strengthening coastal protection, building sea walls, restricting construction in flood-risk areas, and limiting groundwater extraction, are all needed. However, none of them can replace a people-centric approach. We still have not achieved the engineering miracle to ultimately fortify the coastline nor reached an international consensus to drastically reduce emissions. Low-lying coastal settlements and communities are subject to a high risk of submergence. A comprehensive disaster risk reduction plan should be articulated to assist with inevitable relocation where projected hazardous flooding is evident and cannot be contained. Climate-driven mass migration would negatively affect the social and economic security of countries, creating hostility and social anxiety and even leading to climate refugees fleeing to other less disaster-prone countries. That will exacerbate the existing cross-border migration crisis and affect national and economic security.
Investing in planned community relocation and migration to inland satellite cities can help countries avoid forced relocation. Combining this strategy with urban adaptation measures will ensure comprehensive preparedness for future generations. Densely populated capitals and financial hubs should diversify urban investment by anticipating the necessity for satellite cities. Planned relocation should be a new long-term adaptation priority that seriously considers climate-driven disasters — and the time it takes to build a new city from scratch.