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Humans react sensitively to climate changes - mainly to rising temperatures. Their performance and physical well-being can be influenced by heat significantly. Especially elderly and debilitated people and children are affected by the health risks of climate change. Also extreme weather constitutes a growing threat.
Especially the long-term increase in average temperatures in Germany will have an impact on health. With increasing temperatures, disease carriers (vectors) can migrate into new habitats and thereby extend the regional scope of the diseases they transmit. This includes, inter alia, vectors such as mosquitoes, ticks or bugs.
In their development and spread, vectors immediately react to changes in temperature, but also to changing humidity and other environmental factors. In Germany, especially the generally rising temperatures favour the growth and spread of vectors. Mild winters increase the survival rate of many disease vectors. They cause accelerated generation successions and prolonged annual activity periods.
Extreme weather events can also affect the existence of vectors. The inundations caused by the Elbe flood in 2002, for example, entailed ideal conditions for a mass reproduction of mosquitoes.
In Germany, an increased risk potential could emanate from hantaviruses, borrelia and TBE viruses in particular. Hantaviruses are often transmitted by rodents such as bank voles. They can lead to fever and kidney failure in extreme cases. The virus is already particularly widespread in the Swabian Alb, in the Bavarian Forest, Lower Franconia and in the area around Osnabrück.
However, the greatest danger in Germany emanates from borellia or tick-borne encephalitis viruses (TBE). They are transmitted by ticks. In Germany, the Lyme disease is amongst the most frequently vector-transmitted infectious diseases transmissible to humans. At present, TBE risk areas are reported to exist in the states of Baden-Wuerttemberg, Bavaria, Hesse, Rhineland-Palatinate and Thuringia.
Furthermore, climate change entails the risk that new harmful animals or plants can become domestic in Germany although their habitats were previously restricted to tropical and subtropical regions. Due to an increasing global trade of goods and tourism, alien pathogens can be introduced by humans or animals unintentionally, for example through animal transports, feedingstuffs or seeds. The climatic changes, especially the general warming, allow an encroachment of non-native pathogens in temperate climates and their survival in these regions. Against this background, pathogens from southern regions, which were previously found only sporadically in Germany, can occur more frequently in the future. In the particularly warm regions of Baden-Wuerttemberg, potent carriers of the infectious disease Leishmaniasis have been detected already; their original habitats are tropical regions.
Other health risks such as asthma and allergies are caused by changes in environmental conditions as a result of climate change. Thus, the pollen season will start earlier and last longer in future. Furthermore, a higher CO2 concentration in the air can also lead to an increased pollen production. Thus, people with asthma and hay fever suffer more from the symptoms. In recent years, the frequency of allergies caused by pollen has increased significantly in Germany. Newly migrated plants such as the common ragweed (Ambrosia artemisiifolia), which thrive under the changed climatic conditions further contribute to this effect.
Due to an increased number of hot days, also the concentrations of ozone and particulate matter in the air will increase. The direct health effects caused by higher ozone concentration include irritation of mucous membranes, respiratory reactions such as reduced lung functions, cardiovascular diseases, as well as an impaired physical performance. Especially increasing summer high-pressure weather conditions can favour the formation of ground-level ozone.
These high-pressure weather conditions also intensify the solar radiation. The effects of increased UV radiation include sunburn, corneal and conjunctival inflammation, and skin cancer. In Germany, the UV radiation has, however, only slightly increased during the last decade. In the future, a further slight increase is expected.
As a result of climate change, an increase of extreme weather conditions in Germany is expected. Extreme weather events include heat waves, storms, hail, heavy rainfall, floods, avalanches or landslides. Direct effects of such weather extremes can be diseases and injuries, sometimes even fatal injuries. Secondary effects following extreme weather events can cause health risks amongst those concerned by the weather events; these risks include stress, mental disorders, anxiety, or depression and are caused, for example, by the destruction of property or even livelihoods.
The effect of heat waves on human health depends on their intensity and duration. In Germany, heat waves will occur as a result of climate change more frequently and last longer in the future. They can trigger extreme heat stress among humans when high temperatures prevail for a long time, little air movement takes place and a relatively high humidity exists. Stress decreases the physical performance and thus also has a detrimental effect on the society’s productivity in industry and trade.
Especially the human cardiovascular system is stressed significantly by extremely high temperatures. Older people are particularly affected by heat stress due to the fact that their biological capability of regulating body temperature slows down and their ability to give off bodily heat decreases. Thus, demographic change implies that the risk potential of the population increases. Furthermore, the body’s adaptability can be affected by pre-existing conditions such as diabetes or diseases affecting the central nervous system as well as through medication and drug use (alcohol, caffeine, etc.).
In 2003, the heat wave in Germany resulted in approximately 7,000 additional deaths from heart attacks, cardiovascular diseases and kidney failure as well as respiratory problems and metabolic disorders. Overall, it is assumed that EU countries will suffer from an increased mortality rate of one to four percent per degree of temperature increase. As far as Germany is concerned, it is estimated that the annual heat-related deaths will increase by 5,000 in 2071-2100. The winter mortality and snow or ice-induced injuries, however, are expected to decrease due to milder winters. Significant heat impacts are expected to concern major metropolitan areas and the Upper Rhine rift valley in particular, i.e. regions that are relatively hot anyway.
The increase in extreme weather events such as heavy rainfall, flooding and drought will also affect the quality and availability of (drinking) water. Mild temperatures, an increased solar radiation and higher CO2 concentrations in the atmosphere promote plant growth and thus lead to an increase of, for example, blue-green algae (cyanobacteria) in the Baltic Sea and in inland lakes. Because certain blue-green algae produce numerous toxic substances, the quality of affected waters drop significantly. Health effects include skin irritation or gastrointestinal disorders. In the hot summer of 2003, numerous beaches along the Baltic Sea were closed as a result of increased blue-green algae bloom.
If you are interested in obtaining information about possible adaptation measures in the field of action human health, please click here.
The impact of climate change will be felt more strongly in the future – and in Germany too. This is the conclusion reached in what is called the vulnerability analysis, a comprehensive study on Germany's vulnerability to climate change.
