Over the last 50 years, human activities, particularly the burning of fossil fuels, have released sufficient quantities of carbon dioxide and other greenhouse gases to trap additional heat in the lower atmosphere and affect the global climate. In the last 130 years, the world has warmed by approximately 0.85 degree Celsius. Each of the last 3 decades has been successively warmer than any preceding decade since 1850.Sea levels are rising, glaciers are melting and precipitation patterns are changing. Extreme weather events are becoming more intense and frequent.
What is the impact of climate change on health?
Although global warming may bring some localized 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. Climate change affects social and environmental determinants of health, like clean air, safe drinking water, sufficient food, and secure shelter.
Extreme high air temperatures contribute directly to deaths from cardiovascular and respiratory disease, especially in elderly people. High temperatures also raise the levels of ozone pollutants in the air that exacerbate cardiovascular and respiratory disease. Pollen and other 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.
Natural Calamities and Variable Rainfall Patterns
Globally, the number of reported weather related natural calamities has more than tripled since 1960. Every year this result in over 60,00 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. People may be forced to move, which in turn heightens the risk of a range of health effects, from mental disorders to communicable diseases.
Increasingly variable rainfall patterns are likely to affect the supply of fresh water. A lack of safe water can compromise hygiene and which kills approximately 760,000 children aged under 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.
Floods are also increasing in frequency and intensity, and the frequency and intensity of extreme precipitation are 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. They also cause drowning and physical injuries, damage homes and disrupt the supply of medical and health services.
Who is At Risk?
All populations will be affected by climate change, but some are more vulnerable than others. People living in small island developing states and other coastal regions, mega cities, and mountainous and polar regions are particularly vulnerable. Children, in particular, living in poor countries are most vulnerable to the resulting health consequences. The health effects are also expected to be more severe for elderly people and people with infirmities or existing medical conditions.
Measuring the Health Effects
Measuring the health effects from climate change can only be very approximate. Nevertheless, a WHO assessment, taking into account only a subset of the possible health impacts, and assuming continued economic growth and health progress, concluded that 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 under nutrition