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About one-fifth of all countries in the world will face acute water shortage by 2040 as climate change disrupts rainfall patterns and a growing population pushes up demand, according to an analysis by the non-profit research organization World Resources Institute (WRI).
The study ranked all countries according to the severity of the water crisis they are estimated to face, and the Middle East stood out as the most vulnerable region. Fourteen of the 33 countries most likely to suffer water shortfalls are in the region, including nine that are considered extremely susceptible: Bahrain, Kuwait, Palestine, Qatar, the United Arab Emirates, Israel, Saudi Arabia, Oman, and Lebanon.
"The region, already arguably the least water-secure in the world, draws heavily upon groundwater and desalinated seawater, and faces exceptional water-related challenges for the foreseeable future," says the report.
Other nations that are likely to experience shortages include the big economies of the United States, China, and India. These countries are already struggling with water scarcity and will continue face similar levels of water crisis through 2040. However, some regions, including the Southwestern United States and China's Ningxia Province, may see a 40 to 70 percent intensification of their water deficits.
Australia, Indonesia, the Philippines, Mongolia, Namibia, South Africa, Botswana, Peru, Chile, and several North African countries are also at high risk for severe water scarcity by 2040.
For the study, the researchers divided the world into several smaller regions and matched projected rainfall patterns for each region with the expected growth in water demand. A country whose need for water was estimated to be more than 80 percent of its available surface water, was classified to be at "extremely high" risk of water scarcity.
Charles Iceland, a director with WRI's Food, Forests, and Water Programs, said the rainfall projections used in the study were derived from climate models that predict how such patterns would change if global warming continues unabated. Nations closest to the equator, he said, are projected to be hit hardest.
"Climate models tend to agree that in a warmer climate the water that is evaporating off the Equator is going to go higher up in the atmosphere and will travel further north and further south," Iceland said. "So the places that get rains now, are going to be passed by as the water column is going to go further south and north."
In addition to those changing precipitation patterns, water demand projections were calculated based on population growth projections and the pace of economic development.
"With greater economic growth, countries are using more water per capita," Iceland said. He added that the world population is well on its way to reach the 9 billion mark by 2050.
Related: The World Is Running Out of Water
While climate change and population growth are the dominant factors, the dynamics that put pressure on water resources differ from region to region. For example, WRI projects Chile to transition from a moderate level of water scarcity in 2010 to an extremely high level in 2040 due to the combination of rising temperatures and shifting rain patterns. Botswana and Namibia, however, are already facing water challenges, which will be seriously worsened due to climate change.
"The fundamental human right of access to clean water is a huge challenge, even now, in the current climate," Noah Diffenbaugh, a professor at Stanford University's School of Earth, Energy and Environmental Sciences, told VICE News. He too believes that the water crisis will unfold differently from country to country and will require unique, customized solutions.
As much as climate change is stressing water supplies, agriculture - which uses up 70 to 90 percent of a country's rainwater - is in need of a complete overhaul, experts said. More efficient technologies, drought resistant crops, among other techniques could alleviate the stress.
The outcome of heightened water scarcity could be chaos and conflict, particularly in already crisis-prone regions, like the Middle East and Africa, according to many recent studies, including one from the US Department of Defense.
The WRI report highlighted the complex fashion in which such threats are manifested.
"What stood out for me in this report was that a number of countries where we already see a high degree of geopolitical tension were the same countries that ranked very high in the future water stress ranking," Iceland said.
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