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Sea level rise in cities: Preparing for a waterlogged future

Sea levels have been steadily rising over the past few years, but is there something coastal cities can do?

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Quantumrun Foresight
November 8, 2021

Rising sea levels, a consequence of climate change, are already impacting coastal cities globally and could lead to significant demographic shifts in the future. Countries are responding with varied strategies, from the Netherlands' comprehensive infrastructure improvements to China's innovative "sponge city" initiative, while others like Kiribati consider relocation as a last resort. These changes will have far-reaching implications, affecting everything from infrastructure and industry to political alliances and mental health.

Sea level rise in cities context

Since the early 2000s, scientists have observed a steady rise in sea levels, with an estimated total increase of 7.6 cm. This figure equates to an annual increase of approximately 0.3 cm, a seemingly small figure, but it carries significant implications for our planet's future. Scientists say that if the global temperature increases by 1.5 degrees Celsius, a scenario that is becoming increasingly likely given current trends, we could see sea levels rise between 52 to 97.5 cm by the end of this century.

The impacts of these rising sea levels are already being felt, particularly in coastal cities worldwide. In less than 10 years, Indonesia’s capital, Jakarta, has sunk by 2.5 meters due to a combination of sea-level rise and land degradation, leading to severe flooding during typhoon season. This is not an isolated incident; similar situations are unfolding in other coastal cities, highlighting the immediate and tangible consequences of climate change.

Looking ahead, the situation becomes even more critical for nations in Oceania. These island nations are particularly vulnerable to the effects of rising sea levels, with some admitting that their survival is unlikely if current trends continue. Climate change refugees will likely be heavily comprised by these island nations, leading to political and economic instability.

Disruptive impact

Proactive measures are being taken by coastal cities worldwide to mitigate these worsening conditions. The Netherlands, a country with a significant portion of its land below sea level, has adopted a comprehensive approach to this issue. They have reinforced dams and seawalls, created reservoirs to manage excess water, and invested in improving their communities' climate resilience. This multi-faceted approach serves as a model for other nations, demonstrating how infrastructure and community preparedness can work hand in hand.

Meanwhile, China has taken a unique approach to this issue with its "sponge city" initiative. This initiative mandates that 80 percent of urban areas should be capable of absorbing and recycling 70 percent of floodwater. The government plans to implement this approach in 600 cities by the early 2030s. This strategy not only addresses the immediate threat of flooding but also promotes sustainable water management, which could have far-reaching benefits for urban planning and development.

However, for some nations, mitigation strategies may not be enough. Kiribati, a low-lying island nation in the Pacific, is considering a last-resort strategy of relocation. The government is currently in negotiations to buy a piece of land from Fiji as a backup plan. This development highlights the potential for climate-induced migration to reshape geopolitical landscapes and require new international policies and agreements.

Implications of sea level rise cities

Wider implications of rising sea levels may include:

Essential sector infrastructure, such as power and water, investing in technologies that could keep their systems resilient during floods and storms.

Public transportation systems, such as roads, tunnels and train tracks, needing to be re-designed or elevated.

Populations moving from low-lying coastal areas to inland regions causing overcrowding and straining resources in these areas.

The fishing and tourism sectors facing potential decline or transformation.

New political alliances and conflicts as nations negotiate shared resources, migration policies, and climate action plans.

Increased costs for disaster response and infrastructure adaptation, potential decline in property values in coastal areas, and shifts in insurance and investment practices.

Loss of coastal ecosystems, increased coastal erosion, and changes in ocean salinity levels, with potential knock-on effects on biodiversity and fisheries.

Increased stress and mental health issues related to displacement and loss of homes, cultural heritage, and livelihoods, leading to a greater need for social services and support systems.