It’s supposed to be hot again in Germany. Temperatures well above 30 degrees are possible. The heat claims thousands of lives in Germany every year. Rising temperatures lead to excess mortality and increase the rate of certain diseases. Danger lurks especially in cities. This is where “heat islands” develop.
The increase in heat-related mortality is a global phenomenon. In a study published a few months ago in the prestigious journal The Lancet, the authors estimate that over the past 20 years, heat-related mortality has increased by 53.7% among people over the age of 65. Europe is particularly affected. In 2018, only China and India recorded more heat deaths than Germany. Despite all the information in the media, do we still underestimate the danger of dying from the effects of heat?
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As climate change progresses, the number of heat waves, i.e. episodes of extremely high daytime temperatures lasting several days, has also increased worldwide. In Germany this was the case in 1994, 2003, 2006, 2010, 2015, 2018 and 2019. According to the Intergovernmental Panel on Climate Change, the frequency, intensity and duration of heat waves must be expected to increase in the future.
For example, in Munich in the decade 1951-60 just 2.8 days with maximum temperatures of 30°C and more were measured, in the period 2001-2010 it was already 8.7 days, and projections for the last decade of this century result in 12, 8 days. The coolest summers would then be about as warm as our warmest at the moment, and we cannot yet imagine the extremely hot summers of the future.
The dangers of heat to human health have been known for a long time. The heat balance in humans is geared towards a constant temperature of 37°C inside the body. With increasing thermal stress, the demands on the body’s thermoregulation system, cardiovascular system and breathing increase.
Babies and small children as well as elderly and sick people are particularly at risk from heat stress, since their thermoregulation system only works to a limited extent. Older people often do not feel thirsty or sweat less. A lack of fitness and being overweight also play a role. People who are exposed to the blazing summer sun or who wear protective work clothing are also at risk.
It is therefore not surprising that excess mortality occurs in summer months with excessive heat. Unfortunately, detailed data are not available from all federal states. A working group led by the scientist Matthias an der Heiden from the Robert Koch Institute estimates the heat-related deaths in Germany in 2003, 2006 and 2015 at 7600, 6200 and 6100 cases respectively. In the hot summer of 2018, heat-related mortality was around 490 deaths in Berlin alone and around 740 cases in Hesse.
Wilfried Endlicher is a professor at the Department of Geography at the Humboldt University in Berlin. He deals with urban ecology and researches the consequences of climate change for cities and human health. For example, he analyzed urban heat stress and particulate matter pollution in Berlin and examined their effects on human health.
In the particularly vulnerable age groups of 75 to 84 year olds, the heat-related mortality rate was about 60/100,000 and for those over 84 year olds about 300/100,000. These are incidences that we are now familiar with from the corona pandemic. The State Statistical Office of Baden-Württemberg estimates that almost 1,700 additional people died in this federal state in 2019 due to high temperatures. A Europe-wide study by the coordinator Jean-Marie Robine came to the conclusion that in the hot summer of 2003 around 70,000 people died from the heat.
However, heat-related mortality is only “the tip of the iceberg”, so to speak. Not only is mortality increased, but also the rate of certain diseases, ie morbidity. In particular, patients with cardiovascular diseases and diseases of the respiratory system experience an increased burden of disease during heat waves. Studies by a working group led by pneumologist Christian Witt from Berlin’s Charité University Hospital suggest that patients with chronic obstructive pulmonary disease (COPD) suffer from an increased burden of disease during heat waves.
In her doctoral thesis, the Berlin geographer Katharina Scherber examined the hospital admissions of patients with diseases of the respiratory and cardiovascular systems during hot summers, comparing the federal states of Berlin and Brandenburg. It turned out that on hot days, relatively more patients were admitted in the metropolis of Berlin than in the more rural Brandenburg. Apparently, the urban climate increases the risk of suffering from the effects of heat to such an extent that admission to a hospital becomes necessary. The so-called “urban heat island” probably plays a decisive role here: While the temperature differences between city and country are not too great during the day, urban overheating can be up to 10°C compared to the surrounding countryside on “tropical” summer nights. The larger the city, the more intense the nocturnal heat island can be.
The three-dimensional city structures, “sealed” with asphalt and concrete, store the radiant energy of the sun during the day and only release it again slowly at night. In our overheated cities, temperatures hardly drop below 20°C at night; Interiors remain much warmer. In them, restful sleep is hardly possible, which promotes heat stress in the body. Vulnerable groups, such as the patients mentioned or older people, are then particularly at risk, even to the point of dying. In Frankfurt am Main, the number of heat-related rescue service operations increased by 198% between 2014 and 2018, according to a group of authors led by Katrin Steul from the Frankfurt Health Department.
The Center for Medical Meteorological Research of the German Weather Service in Freiburg has been warning of the increasing health risk for decades. The World Health Organization has also published several tips on how to prevent heat-related damage to health. Your danger is further increased by increased ozone and particulate matter levels in the cities. However, heat is insidious, because blue skies and summer sun suggest well-being.
In the meantime, the German Weather Service has also established a heat warning system; however, awareness of the health risks in our aging society is by no means common knowledge. Nursing services and family doctors hardly have time to deal with this problem and to make sure that older people drink enough and stay in cool rooms. It is a task for society as a whole to look after grandma or the neighbor in the hot attic.
In the long term, our cities must also be better adapted to climate change, i.e. more unsealed and better greened. And the containment of climate change, i.e. the drastic reduction of greenhouse gas emissions, must come first in our own interest anyway.
It’s getting very warm again in almost all parts of Germany. The German Weather Service in Offenbach expects “temporarily and locally” hot summer weather. Because Hoch Iosif has spread across Central Europe and is increasingly bringing warm to hot air from the south into the country.
