Worldwide impacts: Human health
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Climate change could lead to a variety of health impacts – both positive and negative. On the negative side, scientists anticipate more cases of malnutrition, heatstroke and waterborne diseases such as cholera. Although some populations will benefit from a reduced risk of cold-related illnesses such as hypothermia, overall a warming world is likely to have negative effects on human health.
In colder regions such as northern Europe, North America and Asia, warmer weather and less severe winters should reduce the risks of hypothermia and other cold-related illnesses. But scientists expect human health in other regions to suffer. Maximum temperatures are predicted to rise faster than average, so a 2 °C increase in the annual average temperature could translate into a 4 °C increase on the hottest day of the year. By the end of the century, maximum temperatures in Europe, China and North America could be 6–8 °C hotter. More frequent and severe heat waves are likely to make cases of heatstroke more common, especially among vulnerable groups such as children and elderly people.
The negative impacts of climate change on food resources are likely to be particularly severe in regions where many people are already at risk of hunger. Even moderate temperature rises are expected to reduce crop yields in low-latitude regions, and diseases affecting animal herds may become more widespread. Without significant adaptation measures, scientists predict that global warming of 3 °C or more could leave millions of people at greater risk of hunger and malnutrition, especially in sub-Saharan Africa and parts of southern Asia and Central America. In addition to immediate health impacts, malnutrition can have long-term consequences for child growth and development.
Scientists predict that continued global warming will increase flood risks worldwide, which in turn could increase the risk of cholera outbreaks and possibly other waterborne diseases. Cholera is a bacterial disease which leads to profuse diarrhoea and vomiting, causing rapid dehydration. Patients usually become infected by consuming contaminated food or water. Flooding often plays a role in the spread of cholera, either by introducing the bacteria to a new area or by worsening an existing outbreak. Flood waters block drainage systems and can allow sewage to contaminate water supplies. Rising water temperatures could have a direct impact on cholera by speeding up bacteria proliferation.