What a surprise in the world of politics at the end of June 2026: a heatwave! Climate change? In Germany, federal states Saarland, Saxony-Anhalt and Brandenberg experienced record temperatures of nearly 42 degrees, followed by the warmest night since records began, at almost 30 degrees. Families struggled to sleep in sweltering top-floor rooms, hospitals were completely overloaded, tarmac cracked, pets and farm animals dropped dead, fledglings tumbled out of overheated nests and died. And thousands of heat-related deaths were registered in Europe. The World Health Organization warned: ‘Europe is the fastest-warming continent on Earth, with temperatures rising at around twice the global average.'
But the German government's reaction, such as it was, was far from empathetic. Federal Chancellor Friedrich Merz, in his air-conditioned Chancellery, offered words of sympathy to the German football team following their elimination from the World Cup, but could find any for the heat-stricken elderly, sick and children, nor for overwhelmed paramedics and nurses. When asked whether heat protection should be a priority at the highest level of government, official spokesman Stefan Kornelius replied that declaring it to be one was ‘not really a solution to a problem'.
In fact, heat-protection plans in Germany are primarily the responsibility of local municipalities. But the federal government has been burdening municipalities with new tasks for years without providing more funding. The obvious result is that many are insolvent: there's no money for climate protection or adaptation. Clinics, schools, nurseries and nursing homes are given no protection from the sun and no air conditioning or heat pumps that can cool in summer, even in new buildings. Moreover, municipal decisionmakers seem happy to forget all about the dreaded topic of climate change as soon as summer is over. And yet there are so many creative ways to cool down cities and rural areas that urgently need to be implemented.
Water and vegetation
Many still believe that global warming and its tangible consequences can be halted simply by renewable energy. It is undoubtedly essential to stop burning fossil fuels, but CO2 reduction is not the be all and end all.
Every day natural environments are being destroyed so that streets, buildings and industrial facilities can be constructed. Primeval forests are cut down to make room for soya or palm oil plantations. Landscapes have been and are being drained, rivers straightened and moorland dried. Soil is compressed by heavy tractors and assaulted by chemical fertilizers and pesticides, ruining the finely balanced structure of large and small soil pores. Water is removed from landscapes as if it were a pollutant, instead of being retained in the soil. The result is that nature is deprived of the opportunity to absorb heavy rainfall and store it for times of drought. Without vegetation, there is nothing to slow down evaporation, and parched soil can no longer store water: the landscape becomes a desert. And when it does rain the runoff flows quickly away, causing floods and ultimately ending in the sea. A 2025 study shows that large quantities of groundwater and soil moisture were lost around the world between 2000 and 2015, leading to a measurable rise in sea level. Crucially, it takes a very long time for dried out soils to regenerate. It is now clear that soil moisture plays an essential, massively underappreciated role in the global water and climate system.
Around half of droughts in Eastern Germany are caused by poor land and water management, according to the hydrobiologist and prominent water researcher at the Helmholtz Centre for Environmental Research in Magdeburg, Professor Dietrich Borchardt: ‘The land's natural function as a reservoir is increasingly being lost. Over the centuries we have gradually drained it, significantly lowering the water table, primarily due to the way we have managed farms and grasslands.' The country and the continent will slowly but surely dry up unless we finally take action.
Natural air con
Have you ever noticed on a hot day that it is much more pleasant in the shade of a large tree than under a parasol? That it is much cooler under leaves than under fabric? That is because parasols cannot perform photosynthesis.
When we imagine the Earth as a living planet, the rivers are its veins and the trees its sweat glands. Because they consume water, plants provide evaporative cooling as well as producing clouds and new rainfall. This cools the Earth tremendously and supports its large and small water cycles. A single large tree evaporates around 400 litres of water on a summer day, producing a cooling effect comparable to ten air-conditioning units. It also catapults bacteria, pollen, spores and organic compounds into the air, where they stick to water molecules. Water forms into clouds that fall as rain, keeping the Earth, its soil and its plants alive. These low-lying clouds are excellent at reflecting sunlight, sending some of the sun's energy straight back into space: immediate climate protection.
Roughly half of Europe's rainfall has its geographical origin in the land, rather than the sea. Basically, rain does not fall from the sky but is created in the soil, as well as the oceans. For that reason, we can reverse some of global warming through ‘greening' and ‘blueing': humus formation and continuous vegetation cover on farmland and grassland, reforestation, forest renewal, rewetting of moorlands and wetlands, soil de-sealing and more. Greening and blueing are much more than forms of climate change adaptation: they offer direct climate protection.
According to a 2024 study, reforestation in Europe since the 1980s has had a quantifiable cooling effect. Average temperatures in central Europe fell by around half a degree, while during hot spells they were reduced by as much as 1.9 degrees. This is above all because of increased evaporation, which encourages cloud formation and lowers heat stress. A study from 2024 shows that the US East Coast has cooled down despite climate change because its woods have been reforested since the 1920s or have been allowed to regrow on earlier farmland. Its landscape is a huge ‘cool spot' in an otherwise overheated nation. Its soil is on average one to two degrees cooler, and up to five degrees cooler on hot days. Restored forests act like the planet's air-conditioning units.
Germany's action plan
A model calculation of the drought-prone Elbe-Elster district in Brandenburg, Germany, shows that more trees and wetlands could reduce the surface temperature by up to 3.5 degrees and so mitigate global warming at the local level. Similar measures can be implemented almost anywhere and were introduced by the former German Minister for the Environment, Steffi Lenke (Greens), as part of the Aktionsprogramm Natürlicher Klimaschutz (ANK, Natural Climate Protection Action Plan). The programme, a milestone in climate policy, will continue until 2029. With a budget of around 4 billion euros, its activities include rewetting moorlands, wetlands and floodplains, setting back embankments, restoring forests, meadows and coasts and encouraging ‘sponge cities', which soak up rainfall like a sponge and have a cooling effect during droughts.
The implementation of the ANK is moving slowly, however: some of the funds have yet to be released, in part because the funding conditions for poorer municipalities were inadequate and they were unable to afford their co-financing share. According to the German Ministry for the Environment, currently led by the SPD, just under 1,300 projects had been approved by the beginning of 2026, mostly in the field of ‘climate-adapted forest management', as well as 156 moorland protection and restoration projects and 97 measures to improve water retention. There were just three projects to develop ‘sponge cities' and one to set back embankments. It is also unclear what will happen after 2029: the lack of permanently employed local ‘carers' to ensure continuity of work is one of the programme's biggest structural problems.
Moorland rewetting, forest renewal, and the restoration of lakes and floodplains have a particularly strong impact on the climate, according to an evaluation of the ANK programme. They cool entire landscapes through evaporation and have other positive side effects, such as preventing species loss and storing CO2.
Sponge cities
A study by ETH Zurich showed that green areas with trees are one of the most efficient ways of cooling cities. Meanwhile, Deutscher Umwelthilfe (Environmental Action Germany) claims that almost a million urban trees in Germany have been lost since 2018, along with their cooling effect, primarily due to deliberate felling. Even if a new tree is planted, for every tree cut down, it takes decades for a seedling to take over the role of the old one – assuming it manages to survive that long without adequate care and sufficient water during hot summers. The universal philosophy should be to let tall, healthy trees stay standing! According to a Lancet study, large cities in the EU are on average 15% covered by treetops. If this figure were doubled, the number of premature heat-related deaths could fall by 40%.
Urban climate research clearly shows that it is possible to create astonishingly cool microclimates during summer. The following all help: de-sealed soils, fresh air corridors, parks, tree-lined streets, Tiny Forests, urban trees, urban gardens, green façades, pergolas, arbours, green roofs, moss walls, water fountains, restored rivers, ponds and pools.
The new model for this kind of urban environment is the ‘sponge city'. The concept was developed by the Chinese architect Yu Kongjian at the end of the 1990s; in 2012 it was applied to the frequently flooded city of Wuhan. Copenhagen adopted the idea after the disastrous flooding of 2011, creating huge areas of land that store rain and prevent floods. The Klimakvarter (climate neighbourhood) in its Østerbro district is designed to be climate-resilient thanks to green roofs and ‘rain gardens'. The latter are planted infiltration areas that form part of sponge cities. They can absorb up to a third more water than a lawn. Rain gardens also filter the air and provide food and nesting sites for birds, insects and small mammals, and water for plants.
Green roofs are also integral to the sponge city concept: they can store up to 80% of rainfall and slowly release it through evaporation. A layer of earth and plants on an appropriately stabilized roof stores water at the same time as protecting indoor spaces against extreme outdoor temperatures: in very hot periods, green roofs have a cooling effect, while in winter they provide insulation and warmth, reducing heating bills.
Soil de-sealing is also extremely important: tarmac and concrete in densely populated cities radiate heat like ovens. Nevertheless, every day in Germany, 51 hectares are concreted over for new streets and buildings. The Infrastructure Future Act recently adopted by parliament is a step in the wrong direction: it protects motorways rather than floodplains. But alternatives are possible: in the Netherlands, for example, the emergence of the Tegelwippen (literally ‘tile-flipping') movement has led to over 200 urban initiatives that compete with each other to see who can de-seal the most land in the quickest possible time.
Thanks to pressure from civil society, Berlin, Hamburg and other large German cities have started transforming themselves into sponge cities. To avoid a ‘tree referendum', the Berlin House of Representatives passed the BäumePlus-Gesetz (Trees Plus Act) at the end of 2025. It stipulates that a million street trees and a thousand Tiny Forests must be planted by 2040, and that every felled tree must be replaced by three new ones. The ‘tree referendum' movement nevertheless criticizes the lack of official support for the pledge, as well as its unclear financial structure. In the Carl Legien modernist housing estate in Berlin, for example, the district authority put an end to a residents' initiative that would have planted two trees in front of the building to combat extreme heat.
In Hamburg, the municipal water utility provider Hamburg Wasser says it is building massive wastewater highways and reservoirs underneath the city to prevent heavy rainfall from overwhelming wastewater treatment plants and sewers. In 2025 the environmental authority ran a public competition called ‘De-sealing: from grey to green', based on the Dutch model. Participation among the population was high, with over 2,200 ideas submitted, but only a dozen have so far been implemented. When in doubt, German authorities still display a tendency towards bureaucracy and control instead of trusting active citizens – which would cut costs as well as decreasing public anger.
Regenerative agriculture and helpful animals
Finally, regenerative agriculture also plays a key role in climate stabilization. It builds up the soil, transforms CO2 into carbon, captures the resulting carbon and stores water in massive quantities. Its methods, including reduced tillage, catch crops, agroforestry, hedges, wildflower strips and the addition of compost and vegetable carbon, all encourage biodiversity and produce healthy foodstuffs: a win-win situation. Many farms have already adopted the approach.
Others contribute to regenerative measures as part of newly established ‘climate landscapes' and ‘sponge regions'. Probably the most ambitious project is ‘Regenerate' on Lake Constance. This border region between Germany, Switzerland and Austria is dominated by conventional orchards and vineyards. The Regenerate project will work alongside landowners, communities, restaurants, retailers, researchers and regional networks to transform it into a climate landscape. Its growing team, financed by donations from private individuals and foundations, has already managed to reach over 300 landowners with 100 hectares in the region. The goal is to create living cycles, fertile soils and diverse, resilient farms. Every farmer and gardener will be supported along the way with advice and training sessions.
Moorlands, wetlands and river floodplains everywhere have also been destroyed, built on or drastically reduced in recent decades, despite being indispensable for stabilizing the water balance and the climate. Volker Zahner, a wildlife ecologist at Weihenstephan University, is convinced that beavers have a vital role to play in the water cycle. By modelling the Isar region, one of his projects concluded that the water surface area in beaver regions had increased by almost a half, the water table had risen by half a metre and evaporation had also risen sharply.
During droughts beavers also serve as volunteer firefighters, specializing in fire prevention. Beavers' lodges can act as fire breaks in megafires: according to a US study, a large lodge can hold over 4 million litres of water and store another 25 million litres underground. If German natural areas had not been extensively cleared of beavers, many wildfires might never have started in the first place. The semi-aquatic rodents have been almost eradicated in Germany, although there are around 40,000 left, mostly in Bavaria and on the Elbe and its tributaries.
A Czech case shows how useful they can be. While public authorities and conservationists in the Brdy landscape conservation area spent years planning an expensive project to restore a watercourse, beavers presented a fait accompli: in record time, a single beaver family constructed a dam that would have cost 1.2 million euros. ‘In the time it took them, we hadn't even managed to get planning permission,' laughs the director of the Czech nature reserve.
All these examples teach us the same lesson: nature helps us when we help it.
