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After a summer of heatwaves, droughts and floods, here's how cities can become more resilient to climate extremes
Ban Ki-moon served as the eighth UN Secretary-General and chairs the Global Center on Adaptation, and Patrick Verkooijen is CEO of the Global Center on Adaptation.
Another summer of climate extremes has inflicted fresh misery on urban dwellers. Weeks of rain have left Karachi, Pakistan’s largest city, knee deep in water and sludge. Torrential rains in Seoul claimed 13 lives and forced the evacuation of hundreds of people from precarious basement flats. Heatwaves, drought and wildfires have raged in Europe. As with most emergencies linked to global warming, it is the poorest and most vulnerable who suffer the most.
We need to stop responding to weather emergencies as if they were freak events. Climate change will bring more frequent and more severe weather extremes, which is why municipal governments and town planners need to start climate-proofing our cities now. We need to protect our citizens and urban infrastructure from the immediate and the longer-term effects of climate change. The task cannot be delayed any longer.
The era of cities
Half of humanity lives in cities. By 2050, that figure will rise to 70%. In China, 500 new cities are being built from scratch. Elsewhere, 150 urban mega-developments are under way in 40 countries. We are entering a new urban age.
Planned cities are a great opportunity to include climate resilience from the start. But older cities need attention, too. In these, we cannot rip out existing infrastructure or raze homes, but we can adapt our urban fabric to cope with climate extremes. Fortunately, there are many climate adaptation solutions for cities that can save lives. In the long run, they also save money. It is time they were implemented at a global scale.
Cooler cities
Temperature records were broken in Europe and in other regions north of the equator this summer. Extreme heat kills, but there are ways in which cities can avert the risk of death. Hyderabad and Ahmedabad in India have pioneered a national “cool roof” program that is as simple as painting roofs white to reflect the heat. This has been shown to lower indoor temperatures by as much as 5°C (9°F) while saving on energy used by air-conditioners.
Tree planting is another sensible option. New York City’s five borough presidents want local authorities to plant a million new trees by 2030 to aid New Yorkers who are increasingly subjected to extreme heat.
Both cool roofs and green areas can help reduce the urban heat-island effect, which is the result of heavily built-up areas absorbing and re-emitting the sun’s heat. Natural landscapes such as forests and water bodies re-emit less heat, which is why people instinctively seek out parks during heatwaves.
Sponge cities
In most of the world, urban development is synonymous with more paved and impermeable surfaces. But what was once a measure of progress is now a vulnerability because paved surfaces cannot absorb excess water in a downpour.
This is what happened in Seoul, which suffered its worst deluge since records began earlier this month. To build resilience against more frequent and intense tropical storms, we need cities such as Seoul to behave more like sponges and less like a waterproof jacket.
Rotterdam and Shanghai, two port cities that are vulnerable to storm surges and flooding from rising sea levels (another consequence of global warming as polar ice caps melt) are actively making their urban fabric more sponge-like.
The two cities are experimenting with covering roofs and public spaces with plants to reduce runoff and improve drainage when it rains. Rotterdam is encouraging residents to rip up their paved driveways and replace them with permeable gravel. Underground car parks are being repurposed to double up as emergency reservoirs to capture and store excess rainwater. In response to the deluge, Seoul’s municipal authorities have revived a plan to diminish the risk of flooding by building a network of underground tunnels.
More equal cities
With so many competing demands, we understand why cash-strapped city governments are tempted to shelve climate adaptation projects. But as India’s cool roof program shows, not all adaptation interventions are expensive and the benefits are often felt immediately.
Furthermore, research from the Global Center on Adaptation (GCA) shows that investing in climate adaptation can deliver healthy economic returns. The overall rate of return on investments in improved resilience is very high, with cost-benefit ratios ranging from 1:2 to 1:10, and in some cases even higher.
The floods in Seoul were a tragic reminder that the poorest and most vulnerable are always the hardest hit by disasters.
Targeted climate adaptation initiatives can help address social inequalities while making communities more resilient to the impact of climate change. More green spaces to combat extreme heat in poor neighborhoods are a good place to start. Improving drainage and sanitation, and working with nature-based solutions such as restoring riverbanks, can also help protect vulnerable communities from flooding. Car-free zones in urban centers and zero-emissions public transport will improve air quality for all.
Cities will soon be home to more than two-thirds of humanity. These thriving centers for living, learning, working and dreaming are particularly vulnerable to climate change. We know how to make our urban environment more climate resilient while bringing about more equal social outcomes. All we need is the vision and the political will to get started.
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