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Updated: Feb 23, 2022

Climate Change is a Water Story

Climate change is closely linked to water issues. For example, many impacts of climate change are related to water. As global warming increases, changes in the water cycle cause droughts, melting glaciers, sea-level rise, storms and floods, becoming more extreme and posing serious risks to the environment and to human life. Climate change also has direct impacts on water scarcity.

Climate change is a change in regular weather patterns of a location over an extended period, usually regarding temperature and precipitation. These changes are mainly caused by human activities which release greenhouse gases such as carbon dioxide, methane or chlorofluorocarbons, nitrous oxide, and ozone, increasing the greenhouse effect. When the sun’s rays enter the Earth’s atmosphere, the rays are reflected off Earth’s surface; some rays reflect into space, whereas others are trapped by the atmosphere, caused by the greenhouse effect. The increase in greenhouse gases causes more rays to be trapped in the atmosphere rather than reflected into space, heating up our Earth.

The Greenhouse Effect Source: UN IPCC

Temperature increases have direct impacts on water

Glaciers and snow caps are melting, and seawater expands as it warms. Both contribute to the rise of the global sea level, which has increased 24 cm since 1880, with an accelerated rate of increase particularly in the last 25 years, and is predicted to rise another 50 cm by 2100. This will cause the salinization of coastal aquifers, further decreasing the Earth’s supply of drinking water. Freshwater from glaciers and snow will decline over the next 100 years, which will decrease the amount of water available during dry seasons in regions where water is supplied by melting water from mountain ranges, affecting 1/6 of the world’s population. This has been observed in some cities along the Andies in South America for example.

Satellite sea level observations

The rise in water temperatures also affects water pollution, with increased sediments, nutrients, dissolved organic carbon, pathogens, and pesticides entering or surviving better in the warmer water. Oxygen concentrations in the water decrease and phosphorus release increase. This will impact ecosystems, human health and water networks. Higher water temperatures promote algal blooms which will affect both ecosystems and human health. A recent study by the Swiss Federal Institute of Aquatic Science and Technology (EAWAG) and the Swiss Federal Institute of Technology in Lausanne (EPFL) shows that viruses in warmer conditions could be less resistant to disinfection, increasing the spread of viruses and making them harder to treat.

Droughts impact around 55 million people each year, and are expected to be more prevalent, especially in the US and southern Canada, Africa, and the Middle East. Drinking water will become ever scarcer while water quality will also be negatively affected. In addition, high population centers will be stretched and stressed from migration of people seeking to escape habitually drought-stricken areas while agricultural areas will require increased supply of pumped ground water for irrigation. Finally, droughts and heatwaves will continue to increase the risk of wildfires.

Floods and heavy downpours have also been increasing and cause the spreading of fecal matter, pathogens and viruses (such as E. coli, Salmonella, and Shigella) when sewers and wastewater facilities become overloaded and flood. Mr. Arthur Vincent, headmaster of the Global Outreach School in Sierra Leone, recounts that about half of the 450 students at his school are affected by diarrhea during the year, particularly during dry season, when low water levels result in higher concentrations of pollutants in drinking water, and at the beginning of rainy season when pathogens are washed into the drinking water source.

The WHO predicts that between 2030 and 2050, climate change will cause 250,000 more deaths per year from malaria, diarrhea, malnutrition, and heatwaves, which are all directly linked with the supply of clean water.

Table reprinted with permission World Health Organization

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