Today’s most at-risk cities are the canaries in the mine. Coastal cities in South and Southeast Asia, urban centers across West Africa and the Sahel and fast-growing cities in and adjacent to the Amazon are already buckling under the strain of climate stress. Metropolises like Cape Town, Chennai and Sao Paulo have come perilously close to running out of water in recent years. We’re already seeing some governments preparing to move their capitals – such as Jakarta for a cool $33 billion – away from the coast, or, as in the case of the Pacific Islands, gearing up to abandon them altogether. Many of these cities were not built with the future in mind, and they are a flashing warning signal of what is coming, and soon. The canaries are on their deathbed – but has anyone noticed?

And a growing number of the planet’s hyper-connected “global cities” are also feeling the heat. In Asia, cities including Delhi and Faisalabad are frequently being forced to shut down on account of ambient air pollution that is literally sky-high. Throughout Europe, killer heat waves are becoming the norm, with thousands of people dying from so-called “heat island effects.” And in the Americas, storms and tidal surges are buffeting cities like Miami and New Orleans, while forest fires made San Francisco and Los Angeles among the world’s most polluted for a few weeks in 2019. While some cities are taking important action to reduce congestion, build green canopies and deploy break-walls to keep seas at bay, these are a drop in the bucket of what’s needed.

Making matters worse, the effects of climate change on cities are going to get dramatically worse, not better. While we cannot predict them with absolute certainty, the impacts will increase exponentially, not linearly. It is very likely conservative projections issued by the IPCC are downplaying the turbulence ahead. Sea rise models rendered by Climate Central likely severely underestimate the scale of the problem. While some cities are taking heroic steps to curb emissions and adapt their cities, it’s time they also start preparing for Plan B. If they do not, cities – especially those in poorer and more vulnerable settings – will literally collapse. The impacts on their hundreds of millions of residents, global trade and commerce and even insurance pay-outs will be in the trillions of dollars.

If there is any good news, it’s that cities have many of the tools they need to start preparing now.

Preparing for Plan B is about adapting a mindset focused on smart, achievable and future-looking adjustments at the local level. We call this the cellular city. A cellular mindset involves hyper-localizing resilience and investing in self-sufficiency and adaptive regeneration. If national and state electricity grids fail, as they have recently from Argentina to the UK, can the city generate sufficient electricity to function? If a city experiences chronic water shortages, are there sufficient “sponge-like” measures in place to capture rainwater, store ground-water or stretch their water-tower reserves? If neighborhoods are flooded, are buildings and parks prepared to accommodate surges, as Dutch cities have been doing for a generation? If food availability declines, can cities grow their own on rooftops as we see in New York? Cellular thinking requires every law, tax, zoning act, procurement policy, new building or purchasing decision to be embedded with local self-sufficiency, adaptability and resilience top of mind.

Building the cellular city means investing in, but moving beyond, mitigation and adaptation. It means acknowledging the “climate emergency” is a global reality, not a remote possibility. It requires seeing climate change as an opportunity for upgrading, retrofitting and re-purposing the urban landscape for a sustainable future. It will involve making investments in public and private buildings, so they are not only green and efficient, but also autonomous and self-sufficient. A certification standard could be developed (similar to LEED) to measure the built environment from the perspective of its resiliency to climate disruption. It also necessitates data-driven impact assessments of future climate stress on urban development, and limiting construction in areas prone to repeat floods, deserts and storms. In short, it entails greater localization of everything from energy production and water supplies to waste management, recycling and reuse of local products, to promote more circular economies at scale.

Fortunately, many cities and city networks are already taking action. Global city coalitions like the C40 and UCLG are galvanizing thousands of cities to draft climate readiness plans, commit to standards, adopt new laws and learn from one another. The smartest cities are those introducing design-changes to account for shocks and stresses. Cities like Amsterdam, New York, Oslo and Singapore are investing in and subsidizing smarter public transport, electric vehicles, renewable energy plants and industrial symbiosis to promote a more circular economy, offering ideas on how to localize resilience and regenerative capacities at a granular scale. Another way to think about cellular cities is the idea of “defense in depth,” making neighborhoods and infrastructure as agile and autonomous as possible. But much more needs to be done, especially in Africa and Asia, which are urbanizing most rapidly.

Currently, the conversation on climate is often framed around two possible outcomes: the possible victory over emissions, or civilizational collapse and mass extinction. What most people instinctively know, but are understandably reluctant to admit, is that the most likely outcome will be somewhere in between. Make no mistake: there will be massive deterioration and degradation of the climate and biodiversity. Hundreds of millions of people face real risks and will be forced to move, and sooner than many of us think. The question is whether we can improve our future lot by making appropriate contingency plans now and ensuring we constantly upgrade them.

While we must do everything we can to prevent climate change from spinning out of control, the reality is that cities are best equipped to lead cellular thinking and a more sustainable future. The cities of the future – the ones that will weather the coming storm – will be cellular.