By the 2090’s climate change is likely to widen the area affected by drought, double the frequency of extreme droughts and increase their average duration six-fold. — World Health Organization
According to the Comprehensive Assessment of Water Management in Agriculture (2007), one in three people are already facing water shortages. Around 1.2 billion people, or almost one-fifth of the world’s population, live in areas of physical scarcity, while another 1.6 billion people, or almost one quarter of the world’s population, live in a developing country that lacks the necessary infrastructure to take water from rivers and aquifers.
Unfortunately, climate change will place dramatic stresses on those regions of the world most at risk for water shortages. This is due to changes in rainfall, increased desertification, and receding glaciers:
Rainfall: Projections of changes in total annual precipitation indicate that increases are likely in the tropics and at high latitudes, while decreases are likely in the sub-tropics, especially along its poleward edge. Thus, latitudinal variation is likely to affect the distribution of water resources. In general, there has been a decrease in precipitation between 10°S and 30°N since the 1980s (IPCC 2007). With the population of these sub-tropical regions increasing, water resources are likely to become more stressed in these areas, especially as climate change intensifies.
Desertification: A recent global analysis of variations in the Palmer Drought Severity Index (PDSI) indicated that the area of land characterized as very dry has more than doubled since the 1970s, while the area of land characterized as very wet has slightly declined during the same time period. In certain susceptible regions, increased temperatures have already resulted in diminished water availability. Precipitations in both western Africa and southern Asia have decreased by 7.5% between 1900 and 2005 (Dai et al 2004).
Glaciers: Water supplies can also be affected by warmer winter temperatures that cause a decrease in the volume of snowpack. The result is diminished water resources during the summer months. This water supply is particularly important at the midlatitudes and in mountainous regions that depend upon glacial runoff to replenish river systems and groundwater supplies. Consequently, these areas will become increasingly susceptible to water shortages with time, because increased temperatures will initially result in a rapid rise in glacial meltwater during the summer months, followed by a decrease in melt as the size of glaciers continue to shrink. This reduction in glacial runoff water is projected to affect approximately one-sixth of the world’s population (IPCC 2007).
via: Climate Institute
- Only 3% of water on the planet is fresh — and just a third of that is accessible to humans. [WWF]
- 1.8 billion are expected to suffer from fresh water scarcity by 2025, mostly in Asia and Africa.[ILO]
- One in six, or 1.1 billion, people do not have access to a safe and adequate water supply. This number could increase to 2.3 billion by 2025. [UNEP]
- Today, 41% of the world’s population lives in river basins under water stress. [WWF]
- By 2020, between 75 million and 250 million people are projected to be exposed to increased water stress due to climate change in Africa. [UNEP]
- 1.8 million people die every year from diarrheal diseases (including cholera), most of whom are children under 5 in developing countries. Nearly 90% of these deaths are attributed to unsafe drinking water, inadequate sanitation, or poor hygiene. [WHO]
- Climate change is expected to account for about 20% of the global increase in water scarcity this century. [World Resources Institute]
- By the 2090’s climate change is likely to widen the area affected by drought, double the frequency of extreme droughts and increase their average duration six-fold.” [WHO]
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