How climate change can affect human health

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UNESCO, Nairobi, Kenya

The World Health Organization (WHO) estimates that, since the 1970s, climate change has been responsible for over 140,000 extra deaths worldwide each year. As well as the immediate dangers that heat waves, floods and storms can cause, rising temperatures and extreme weather events also pose longer term threats.

The WHO notes that these include:

• Hunger and malnutrition: As the climate so heavily influences agriculture, changes that reduce yields can threaten food security. In the late 20th century, the Sahel region experienced one of the worst famines in history due to decades of crippling drought; in 2011, drought in East Africa killed at least 50,000 people.

• Water-borne diseases: Climatic conditions strongly affect water-borne diseases such as cholera, which cholera thrives during periods of increased rainfall. If these conditions intensify with climate change as projected, scientists expect to see more outbreaks, particularly in areas with poor sanitation or where flooding has occurred.

• Vector-borne diseases: Climate change’s impact on diseases such as malaria and is not yet clear. Warmer temperatures may affect the life cycle of mosquitoes in ways that facilitate their transmission of diseases. In too hot and dry a climate, though, mosquitos cannot survive. Other diseases such as Rift Valley Fever – caused by a virus that mosquitoes transmit to people – are projected to increase in prevalence.