Effects of climate change on human health
The effects of climate change on human health are increasingly well studied and quantified.[1][2] Rising temperatures and changes in weather patterns are increasing the severity of heat waves, extreme weather and other causes of illness, injury or death. Heat waves and extreme weather events have a big impact on health both directly and indirectly. When people are exposed to higher temperatures for longer time periods they might experience heat illness and heat-related death.[3]
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In addition to direct impacts, climate change and extreme weather events cause changes in the biosphere. Certain diseases that are carried by vectors or spread by climate-sensitive pathogens may become more common in some regions. Examples include mosquito-borne diseases such as dengue fever, and waterborne diseases such as diarrhoeal disease.[3][4] Climate change will impact where infectious diseases are able to spread in the future. Many infectious diseases will spread to new geographic areas where people have not previously been exposed to them.[5][6]
Changes in climate can cause decreasing yields for some crops and regions, resulting in higher food prices, food insecurity, and undernutrition. Climate change can also reduce water security. These factors together can lead to increasing poverty, human migration, violent conflict, and mental health issues.[7][8][3]
Climate change affects human health at all ages, from infancy through adolescence, adulthood and old age.[7][3] Factors such as age, gender and socioeconomic status influence to what extent these effects become wide-spread risks to human health.[8]: 1867 Extreme weather creates climate hazards for whole families, particularly those headed by women. It can also reduce the earning capacity and economic stability of people. Populations over 65 years of age are particularly vulnerable to heat and other health effects of climate change.[7] Health risks are unevenly distributed across the world.[8] Disadvantaged people are particularly vulnerable to climate change.[3]: 15
The health effects of climate change are increasingly a matter of concern for the international public health policy community. In 2009, a publication in the general medical journal The Lancet stated that "Climate change is the biggest global health threat of the 21st century".[9] The World Health Organization reiterated this in 2015.[10]
Research shows that health professionals around the world agree that climate change is real, is caused by humans, and is causing increased health problems in their communities. Studies also show that taking action to address climate change improves public health. Health professionals can act by informing people about health harms and ways to address them, by lobbying leaders to take action, and by taking steps to decarbonize their own homes and workplaces.[11]
Studies have found that communications on climate change that present it as a health concern rather than just an environmental matter are more likely to engage the public.[12][13]
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Climate change is increasing the periodicity and intensity of some extreme weather events.[44] Confidence in the attribution of extreme weather to anthropogenic climate change is highest in changes in frequency or magnitude of extreme heat and cold events with some confidence in increases in heavy precipitation and increases in the intensity of droughts.[45]
Extreme weather events, such as floods, hurricanes, droughts and wildfires can result in injuries, death and the spread of infectious diseases. For example, local epidemics can occur due to loss of infrastructure, such as hospitals and sanitation services, but also because of changes in local ecology and environment.
Examples include:
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The effects of climate change on human health can be grouped into direct and indirect effects.[8]: 1867 Both types of effects interact with social dynamics. The combination of effects and social dynamics determines the eventual health outcomes. Mechanisms and social dynamics are explained further below:
These health risks vary across the world and between different groups of people. For example, differences in health service provision or economic development will result in different health risks for people in different regions, with less developed countries facing greater health risks. In many places, the combination of lower socioeconomic status and cultural gender roles result in increased health risks to women and girls as a result of climate change, compared to those faced by men and boys (although the converse may apply in other instances).[8]
The following health effects that are related to climate change have been identified: cardiovascular diseases, respiratory diseases, infectious diseases, undernutrition, mental illness, allergies, injuries and poisoning.[8]: Figure 2
Health and health care provision can also be impacted by the collapse of health systems and damage to infrastructure due to climate-induced events such as flooding. Therefore, building health systems that are climate resilient is a priority.[14][3]: 15
Health risks from changes in air quality[edit]
Indoor air quality[edit]
Indoor air pollution is known to affect the health, comfort, and well-being of building occupants. It has also been linked to sick building syndrome, respiratory issues, reduced productivity, and impaired learning in schools. Indoor air quality is linked inextricably to outdoor air quality.[66] Climate change can affect indoor air quality by increasing the level of outdoor air pollutants such as ozone (see next section) and particulate matter.[67] There are numerous predictions for how indoor air pollutants will change in future.[68][69][70][71] Models have attempted to predict how the forecasted scenarios will affect indoor air quality and indoor comfort parameters such as humidity and temperature.[72]
The net-zero challenge requires significant changes in the performance of both new and retrofitted buildings. Increased energy efficient housing (without good ventilation systems) can trap pollutants inside them, whether produced indoors or outdoors, and lead to an increase in human exposure.[73][74]
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