Climate change affects social and environmental determinants of health – clean air, safe drinking water, sufficient food and secure shelter. Although global warming may bring some localised benefits, such as fewer winter deaths in temperate climates and increased food production in certain areas, the overall health effects of a changing climate are likely to be overwhelmingly negative.
Globally, the number of reported weather-related natural disasters has more than tripled since the 1960s. Every year, these disasters result in over 60,000 deaths, mainly in developing countries. Rising sea levels and increasingly extreme weather events will destroy homes, medical facilities and other essential services. More than half of the world’s population lives within 60 km of the sea.
Extreme high air temperatures contribute directly to deaths from cardiovascular and respiratory disease, particularly among elderly people. High temperatures also raise the levels of ozone and other pollutants in the air that exacerbate cardiovascular and respiratory disease. Pollen and other aeroallergen levels are also higher in extreme heat. These can trigger asthma, which affects around 300 million people.
Ongoing temperature increases are expected to increase this burden. Increasingly variable rainfall patterns are likely to affect the supply of fresh water. A lack of safe water can compromise hygiene and increase the risk of diarrhoeal disease, which kills approximately 760 000 children aged below 5, every year. In extreme cases, water scarcity leads to drought and famine.
By the late 21st century, climate change is likely to increase the frequency and intensity of drought at regional and global scale, according to climate experts.
Floods are also increasing in frequency and intensity, and the frequency and intensity of extreme precipitation is expected to continue to increase throughout the current century. Floods contaminate freshwater supplies, heighten the risk of water-borne diseases, and create breeding grounds for disease-carrying insects such as mosquitoes.
Climatic conditions strongly affect water-borne diseases and diseases transmitted through insects, snails or other cold blooded animals. Changes in climate are likely to lengthen the transmission seasons of important vector-borne diseases and to alter their geographic range. The Aedes mosquito vector of dengue is also highly sensitive to climate conditions; and studies suggest that climate change is likely to continue to increase exposure to dengue.
Though it is difficult to measure the health effects from climate change accurately, according to WHO assessment, climate change is expected to cause approximately 250 000 additional deaths per year between 2030 and 2050 – 38 000 due to heat exposure in elderly people, 48 000 due to diarrhoea, 60 000 due to malaria, and 95 000 due to childhood malnutrition.
(Read the full part of this article in the March issue of Safety Messenger Magazine 2016)