Our civilization was built for a climate that’s vanishing

You can learn a lot about the climates we live in by the buildings we construct.

The steep roofs of Thai temples and Norwegian stave churches are clues to the heavy loads of rain and snow that fall in those countries, which threaten to damage a structure if they don’t slide quickly to the ground. The traditional mud brick architecture of Africa’s Sahel is a marker of an arid environment with hot days and cool nights, where thick adobe walls can keep the interior cooler than the outside air.

That parsimonious approach — adding only the features that are necessary for us to thrive in local conditions — applies across the world and throughout history. We’ve built our civilization on a series of local equilibria, paying the short-term cost of adapting to immediate conditions to avoid the long-term risks from extreme weather. With each tenth of a degree that the planet warms, we are breaking those equilibria.

Climate records are falling on a daily basis right now. In Tokyo, which swelters in summer at the best of times, city center temperatures are currently running 9C (16F) above the seasonal average, with the mercury rising to 38.8C (101.8F) in one northern suburb. In Delhi, 25,000 people were evacuated to escape the worst floods in 45 years. Phoenix has seen an unprecedented number of consecutive days over 110F (43C), while temperatures breached 50C (122F) in California’s Death Valley and western China’s Xinjiang region and may soon do so in parts of Turkey.

Smoke from Canada’s forest fires recently descended on the north and eastern U.S. for the second time in a month, while Italy is forecast to experience its highest temperatures on record within days. Waters off the Pacific coast of South America that are already the warmest they’ve been in two decades have helped drive the world to the hottest month since records began. It’s likely the current El Nino — the multi-year climate cycle that tends to bring hotter conditions to the places where most people live — will persist into next year, and possibly worsen.

A common rejoinder to those who advocate action on climate is that human ingenuity will allow us to minimize the consequences of a warming planet. Such adaptation will have steep costs, however, at a time when a faster shift to renewable power, energy efficiency and electrified transport will save money compared to continuing on our current path. Worse, it assumes that such radical adaptation will even be possible. Human history suggests that, to the contrary, we’ve always been at the mercy of such shifts.

A drying climate millions of years ago may have led early hominids to leave the forests, shed their fur and walk on two legs to better stalk prey in the savannahs of eastern Africa. Cooler, drier conditions six millennia ago may have driven nomadic pastoralists into the valleys of the Nile, Tigris-Euphrates, Indus and Yellow rivers, the cradles of civilization outside of the Americas.

Humid conditions in Europe and western Asia between the 5th and 7th centuries may have led to the spread of rat-borne plague, devastating the Byzantine and Persian empires and aiding the Islamic conquests.

The warming caused by two centuries of industrial civilization has already put us well within the range of such epoch-making events, with current temperatures on a par with those 6,000 years ago that heralded the birth of urban civilization.

That is made more wrenching by how precisely we’ve adapted ourselves to current conditions. Every storm-water channel and every building heating or cooling system has been built for a climate that is rapidly disappearing. Patterns of trade and global supply chains are easily disrupted by ecological disasters. Politics is built on geographic coalitions that may dissolve as climate change alters the trajectories of different regions, or sends refugees to seek homes elsewhere. By 2050, some 3.4 billion people will be living in countries facing ecological catastrophes.

The extreme weather of the past few years — from wildfire smoke in the U.S. and disappearing rivers in Europe and China — should be evidence that there are no places that will be spared from the coming upheaval. Relatively wealthy regions such as Germany, Benelux and the Beijing metropolitan are may be the most at risk of damaging urban heatwaves, according to one study last month.

Modern society is a sort of collective insurance policy protecting us against the worst external shocks. But insurance policies have a price that rises with the cost of disasters — and we don’t know the point at which they will break altogether, with unpredictable but dire consequences for all of us.

We do, however, know that disasters like those currently unfolding across the northern hemisphere will affect more and more of us. To avoid that unpredictable future, the modest and often negative cost of a switch to cleaner energy and food systems seems a very small price to pay.