"The whole of Central Europe is a potential malaria distribution area," says Thomas Kistemann, a medical doctor and geographer employed at the Institute for Hygiene and Public Health at the University Hospital Bonn (UKB). His area of expertise is environmental health issues. "When average temperatures rise, the risk of malaria will be particularly high in Bonn because of thermal conditions in the region."

Located in the Kölner Bucht (Cologne Bay), Bonn experiences little movement of air masses. It is humid and it is one of the warmest regions in Germany. Winters are mild, without long periods of frost - an ideal breeding ground for mosquitoes. Until the early 19^th century, the Rhine was surrounded by marshes, allowing malaria-carrying Anopheles mosquitoes to multiply. Straightening the course of the river helped. But "unfortunately, the situation can deteriorate easily when more mosquito species come with rising temperatures," says Kistemann. The Zika virus and dengue fever, transmitted by tiger mosquitoes, are also diseases that could potentially spread in Germany as temperatures rise.

But Kistemann believes that other health implications are more pressing for Bonn and the region. He includes the physical and psychological impacts of natural disasters in his assessment of the influence of climate change on human health. Such events are likely to increase. The catastrophic consequences of a flood like the one in the Ahr valley, with many dead and injured, are obvious. In addition, there is collateral and consequential damage to health. "During floods, the sewage infrastructure can be destroyed and water contaminated," the specialist cites as an example.

A common disease that is transmitted through water and mud is leptospirosis. The bacterium enters the body through the skin or mucous membranes. In most cases, the course of the infection is like that of influenza, but it can also be severe and even fatal. According to Kistemann's prognosis, we will have to deal with this disease more frequently during global warming. "Every time the Rhine floods, a handful of people are already infected with it," he says.

Bottlenecks in supplies and impassable terrain are also consequences of floods. For example, dialysis patients who must go to hospital regularly could be cut off from vital medical treatment.

Ulrike Schmidt is deputy director of the Department of Psychiatry and Psychotherapy at the UKB. Among others, she is treating the flood victims from the summer of 2021. Not only do many of the people in the flood areas still suffer from trauma after-effects. In the future, the consequences of climate change will also lead to more mental health problems in general, she predicts: "When the body is stressed, whether by heat or even by natural disasters, the psyche is also more vulnerable."

Heat is thus likely to become the biggest challenge in the near future, especially for vulnerable groups, she says. "Elderly people, children, pregnant women, people who work outside, people with pre-existing health conditions such as cardiovascular disease, respiratory disease, mental health disorders, diabetes - and people who are marginalised or on the outskirts of society are among the most vulnerable to extreme heat," says Vladimir Kendrowski, Technical Officer for Climate Change and Health at the WHO European Centre for Environment and Health in Bonn. The ageing population in Europe is growing and will continue to do so in the coming decades, thus increasing the number of people who are particularly vulnerable to extreme heat.

According to a projection by the Federal Statistical Office, 85,285 people died in Germany this July. This figure is twelve per cent, or 9130 cases, above the 2018 to 2021 median for the month. Calculations by the Climate Service Centre Germany (Gerics), based in Hamburg, have shown that between 2036 and 2065 it is likely to be around 1.5 degrees warmer on an annual average in the region. Although a direct correlation between hot temperatures and higher death rates cannot be established, mortality rates are particularly high in periods of very hot weather.

The most recent heat waves in June and July probably both claimed well over 3000 lives in Germany. This is shown by data from the Federal Statistical Office. "Many diabetics came to my endocrinology consultation during hot spells, and this was incredibly stressful for them," says Dietrich Klingmüller. For many years he was head of endocrinology and diabetology at the University Hospital in Bonn. He recently retired and is now involved with the activists of "Scientists for Future" and "Health for Future". Klingmüller explains what happens to diabetes sufferers when it's hot: "The body produces more stress hormones such as cortisol, sugar levels are raised and the balance can go haywire." People with an overactive thyroid also struggle: too much thyroid hormone leads to increased heat production, which is particularly uncomfortable in the hot weather, he said. "Heat leads to heavy sweating. As a result, the sweat on the skin evaporates, leading to a lack of blood volume. Blood pressure can drop," Klingmüller says. This is dangerous for older people who often drink too little, especially if they are taking blood pressure-lowering medication.

Thus, facilities where vulnerable groups come together in particular need to prepare for changed conditions in the coming decades. The University Hospital also has a long way to go in terms of preparation - especially in relation to rising temperatures. "Patient rooms are not normally air-conditioned," says Charlotte Kaspari, division manager in the UKB's facility management. She looks after the project management of the technical building equipment.

"In the 80s and 90s, people built windows as big as possible to let in light. Now that' s coming back to haunt us," she says. Since the trend is more towards short inpatient treatments, it can be assumed that patients who will be in hospital for a longer time in the future will be more seriously ill. And correspondingly sensitive to heat. "Now the motto is still: no air conditioning unless it is absolutely necessary, but that will change," Kaspari is convinced. The new heart centre, which is scheduled for completion in 2025, is already air-conditioned, he says.

The elderly also belong to the risk group. "Most of our residents suffer from the heat in summer," says Sandor Sobothe, director of the Marienhaus retirement home in Noeggerathstraße in Bonn's city centre. "We are surrounded by concrete; the building substance heats up dramatically." Only the treatment room is air-conditioned to keep medication cool, he says. For Sobothe, a lot has to change in the way social institutions are built in the coming decades. "But it's all about money," he notes.

Jean-Pierre Schneider, Caritas director in Bonn, confirms this. This summer, Caritas Bonn, which runs the Marienhaus, took part in a project of the Freie Wohlfahrtspflege in NRW that surveyed temperatures in inpatient facilities: In 68 facilities from all over NRW, a mean value of 26.9 degrees was calculated in the residents' rooms. "These temperatures can no longer be compensated for by normal thermal measures; structural measures are needed," says Schneider. In February, the KfW 40 subsidy was cancelled by the Federal Minister of Economics, Robert Habeck, "which leaves huge gaps in our planning," says Schneider.

Meanwhile, the city of Bonn is concerned about another risk group, toddlers - or at least it intends to do so. A survey entitled "Introductory and Orientation Consultations on Climate Adaptation in 20 Kitas in Bonn" ran until November 2021. According to information from the press office, "mainly older existing kindergartens, which are to be upgraded for future use with measures that can be implemented quickly," were examined. It was revealed that many kindergartens lack sun protection devices on the building and on the outdoor facilities. Isabel Klotz from the press office: "The aim of the concepts drawn up was to apply for further funding to implement the measures identified." However, due to the high interest in the funding programme, the announced second funding window of the programme could not be opened until today. And: "Due to the high workload in the municipal building management, the measures have not been tackled so far." There is no timetable yet.