Europe is heading towards a sustained decline in population. In the coming years, most EU countries will experience demographic decline as a direct consequence of low fertility rates and an ageing population.

This is not a new phenomenon. Without immigration, Europe would already have started to lose population a decade ago. Spain's population has grown by 24% since 1990 thanks to an influx of foreign population and a favourable population pyramid [Fig. 1].

Despite the advances in organic farming over recent decades, European agriculture still depends on a difficult-to-replace input: ammonia. Without it, it would be impossible to produce the fertilisers that sustain around 90% of Europe’s agricultural output. The problem lies in how ammonia is produced: a highly energy-intensive process based on fossil fuels that, on a global scale, consumes around 2% of primary energy and generates 1.5% of CO₂ emissions.

The economic and social progress of countries in the long term is determined, among other things, by the distribution of their population across the territory. The evidence tells us that the concentration of the population in large urban areas facilitates efficiency in the provision of services, promotes innovation and the exchange of ideas, and encourages the attraction of talent, generating more growth and more employment.

Almost everything we do on the internet is protected by digital security systems: from sending a WhatsApp message to making a bank transfer or saving our photos in the cloud. This protection is based on mathematical formulas that are very difficult to break, at least for today's computers. However, the advance of quantum computing is opening a new era in technology.

What if every step we took could light up a streetlight? What if windows not only let in light, but also captured it and transformed it into energy? The cities of the future will not only consume electricity; they will also generate it through their architecture, transport systems and daily life. This will be made possible by distributed microgeneration, in which small devices generate electricity near the point of use. This reduces reliance on large infrastructures, minimises transmission losses and enhances system resilience.

What if the main street of a city is pedestrianised, if the railway network is buried or if a new neighborhood is built? Until now, we have not been able to determine the precise consequences of such a public intervention. Soon, however, it will be unthinkable to make a decision in the real world without first testing it in the virtual environment.

Living alone, moving far from our usual place of residence, working remotely, or socializing more through social media and less by meeting for coffee are some of the realities reshaping our social and emotional relationships. These trends help explain, in part, the rise in mental health issues among both young and older adults. In this context, artificial intelligence is emerging as a source of companionship and a tool to address loneliness.

Genetic engineering has paved the way for a new generation of trees capable of capturing and storing more CO2 for longer. Recent techniques such as CRISPR-Cas and base editing enable the DNA of plants to be modified with great precision, improving their photosynthetic efficiency, accelerating their growth, and promoting the development of deeper roots that can store carbon in the soil for centuries.

Printing at home a broken washing machine part or a LEGO piece may become a reality in the coming decades. Since their emergence in the late 1980s, 3D printers have evolved to become one of the most promising technologies for manufacturing goods. Although it is still a relatively young technology, its application in sectors such as construction —in Japan, a 3D printed train station was built in less than six hours—, automotive, aerospace, pharmaceuticals and food is already enabling significant efficiency gains and greater product customisation.

Ecosystem insurance has emerged as an essential tool for financing the restoration of natural areas as extreme weather events increase in frequency and intensity. To date, most have focused on covering damage to reefs and mangroves as the tools to quantify the impact of severe weather events on these ecosystems are well developed.