In the coming years, many developed coastal cities around the world will be facing a severe risk of floods.

Global warming is now significantly, around the world, globally increasing the number of people at risk. According to climate change experts, cities from New York in the U.S. to Dhaka in Bangladesh are likely to be heavily affected. Temperature rises from climate change will be significantly exaggerated in urban areas and their inhabitants will have to find somewhere else to live. In most cases they will move to where the opportunities and the jobs are, the nearest habitable city. With 70% of the world’s population expected to live in cities by 2050, the impact of climate change on the urban environment appears more pressing than ever before.

Historically, due to their association with maritime trade and transport, cities built up around water highways and coastal regions have been flourishing and today, a disproportionately high number of the world’s cities are located in areas that are now increasingly at risk of floods. In the coming years, extreme, once-in-a-lifetime, weather events such as flash floods and coastal hurricanes are going to become more and more commonplace. In America alone, cities like New York, Miami and New Orleans are facing terrible exposure to floods and unlike cities such as Rotterdam, they do not have the appropriate defences, such as vast flood barriers and evacuation avenues, to prevent them. In the future, major cities will have to adapt to the reality of regular flooding by building such new infrastructures.

Over the next century, global temperatures will rising by at least between three to five degrees. In large cities, due to the urban heat island effect phenomenon, temperatures will far exceed that level. Aside from increased instances of heat-related deaths, the irony of the urban heat island effect is that it stimulates a demand for air conditioning which will contribute to global warming and create a negative feedback loop and in certain parts of the world entire countries could be irrevocably damaged by such a negative feedback effect. In the same way, over the next century, the rise in global sea levels will cause saline intrusion into all coastal cities aquifers systems making fresh water undrinkable. When fresh water distribution systems will be buckling under the impact of city floods, stock piles of bottled water will be have to be rationed.

High intensity rainfalls will also pose a threat. Even in a developed city like London, which is very well protected by the Thames barrier, high intensity rainfall could create problems with the old sewage system causing the potential spread of microbial disease. Urbanities of the future will be defined not just by how they restrict their own contributions to climate change, but by the infrastructure and policies they employ to defend against the consequences of it. Accordingly, many of the cities in the C40 network have already started to implement adaptive measures. In Seoul, for instance, they have removed a highway and restored an ancient river running through the city. Meanwhile, New York and Tokyo have led the way with green rooftops and urban gardens. Urban green spaces are going to be more critical than ever. Not only do they absorb heat and rainfall, but they provide opportunities for small scale food cultivation so city dwellers can become a little less dependent on imports.

In the next century, the accelerated urbanization caused by climate change, will mean that for most cities, the only way is up. Like in Singapore today, in order to accommodate the flood of migrants, we will see a massive proliferation of efficient high-rise residential tower blocks, over small areas of land.