This week was London Climate Action Week, an international event that brought researchers, leaders and activists to the British capital to discuss climate change. As delegates gathered in the city, they experienced the nature of the problem first-hand: temperatures in parts of the United Kingdom topped 36 degrees Celsius (97F), and London itself sweltered. The city clearly struggled to cope, as exemplified by an event scheduled to discuss extreme heat being cancelled because of the extreme heat.

A heatwave has engulfed Europe. The physical phenomenon is well understood. The jet stream dips to the west, allowing hot air from North Africa to make its way over the continent. An area of high pressure then strengthens, staying in place for days, creating a dome that traps hot air and suppresses cloud formation. Temperatures increase. Europe is turning into an oven. And the fact that it is consistently breaking records is a strong indication that the long-term warming of Europe —the continent that is warming the fastest— is having an effect.

Such weather patterns have happened before, of course, but they are now becoming deeper and more frequent. They are no longer occasional, extreme events, but a new normality. And they are also revealing the structural inadequacy of Europe’s built environment: not insulated enough to keep the heat out, nor uniformly air-conditioned enough to keep it cool. This problem is particularly evident in places like Paris or London, which are currently at the centre of this latest extreme and which were once notorious for their long winters and grey skies rather than for their heatwaves. Historically, the local climate allowed developers to opt for designs that ignore the challenges of warm, sunny climates—a neglect that now risks becoming negligence.

Things will get worse. As average temperatures continue to rise, the number of days of extreme heat will increase. Even southern European cities, once comfortable with the warm, benign Mediterranean climate, will struggle. The stakes are high. The heatwave of 2003 killed around 70,000 people. Efforts to adapt followed, but nearly two decades later, the summer of 2022 saw over 60,000 heat-induced deaths, suggesting that those efforts were insufficient. This year’s heatwave may be worse still. European cities are not ready.

What does this mean for decision-makers? The UK Climate Change Committee has summarised the problem pithily: “The UK was built for a climate that no longer exists”. This is true for most of Europe. A new urbanism is needed. To be fair, mayors across the continent have recognised the challenge and have begun to respond. Greening cities is an important part of that response. Paris, for example, has pledged to plant thousands of trees in the hope of mitigating the effects of concrete and stone buildings absorbing and radiating heat over the course of the day.

New buildings offer another opportunity to build better, and because the EU, recognising that most member states face a housing crisis, is supporting the development of new housing stock, it is possible to improve designs and finally build for heat. But the existing, historic stock continues to be a problem, also because there is a lot of it: in most EU member states, less than a quarter of residential building stock was built after 2000, while close to half is over 60 years old. Countries like Italy will struggle to reconcile new building functionality with historical heritage. The first requires innovation and new materials to deal with climate change. The second demands preservation. For a continent whose identity is anchored in history, building a different future is far from easy.

Besides, there are real structural barriers to some of the most common interventions. Take tree-planting as an example. Florence’s tourist-flooded streets are almost entirely devoid of trees, surrounded as they are by imposing palaces from centuries ago, when powerful families competed for size at the expense of public space. Those palaces attract millions of tourists and line Florence’s narrow streets beautifully, but leave little room for vegetation. Other cities in Europe have fared better, with tree-lined boulevards or green spaces inspired by the garden city movement, making additional tree planting easier. But other constraints on preserving the built environment still make it difficult to innovate. In Europe, history and the future often appear locked in a zero-sum game.

The problem is more complicated still because, even in the midst of a heatwave, one cannot forget that heat is not the only climate-related concern for European cities. They are vulnerable to water extremes, for which history also risks becoming a difficult obstacle on the path to resilience. For example, water mills powered the mechanisation of the Middle Ages, transforming the European textile industry, and required canals, which became the principal transport infrastructure until trains came along in the 19th century. But in many European cities today, many of those canals have been buried under 20th-century roads, with important, unintended consequences.

For example, Bologna, the medieval town home to the oldest university in Europe, has 40 kilometres of canals under its streets. They once carried goods and powered mills, but they now carry the floodwaters of extreme precipitation, putting the city at risk as cellars explode when floods rush through this underground network. Transforming European cities then means reconciling this deep heritage with rapidly changing material conditions.

The struggle is not just technical — a challenge for architects and engineers — but profoundly political: most strategic issues in Europe’s competitiveness and security agenda matter when it comes to transforming the continent’s built environment. Increasing air conditioning, for example, requires an electricity grid capable of accommodating the increase in demand. This comes at a time when data centres, electric transport, and automation are putting pressure on the energy system, and when the sources that feed it are increasingly intermittent and distributed. Of course, the most vulnerable could in theory be moved to higher ground — temperatures generally fall with altitude — but it would require rethinking the services and infrastructure available to mountain territories, which have been depopulating for several decades.

Modifying urban outdoor spaces requires managing the hydrological consequences of more porous cities, even as they become more vulnerable to extreme precipitation. Meanwhile, the regional infrastructure that forms the last line of defence against floods and droughts is proving inadequate for the climate of the future, and Europeans are ageing and will need more public health services just as those services are strained by the impacts of a changing climate.

This week’s heatwave is a harbinger of what is to come. It is a reminder that Europe’s cities and landscapes must adapt to changing material conditions or suffer substantial consequences. Whether Europe succeeds will depend on its willingness to focus on building the future, rather than just on the conservation of the past. For a continent whose identity is rooted in history, this may be the most strategic challenge of all.

The views expressed in this article are the author’s own and do not necessarily reflect Al Jazeera’s editorial policy.