World water supplies may be severely stressed in coming decades because of global climate change linked to the burning of fossil fuels such as coal and oil. The U.S. West is one of the places that has the most to lose with water scarcity, but many other regions around the world will face similar challenges.
Here are some facts and projections on water and climate change:
-- Temperatures are likely to rise by between 1.1 and 6.4 Celsius (2.0 and 11.5 Fahrenheit) and sea levels by between 18 cm and 59 cm (7 inches and 23 inches) this century, according to the U.N.'s Intergovernmental Panel on Climate Change.
-- Climate change model simulations for the 21st century see increased precipitation at high latitudes and tropical areas; decreased rainfall in sub-tropical regions.
-- Warming in the western U.S. mountains is projected to cause decreased snowpack, more winter flooding and reduce summer flows, exacerbating competition for over-allocated water resources.
-- Major challenges are projected for U.S. crops near the warm end of their suitable range or which depend on highly utilized water resources.
-- In southern Europe, climate change is projected to worsen conditions like high temperatures and drought, and reduce available water, hydropower potential, summer tourism and crops in general.
-- In Latin America, productivity of some important crops will decrease, while disappearance of glaciers in the Andes will affect water supplies for human consumption.
-- In Africa, by 2020, between 75 and 250 million people are projected to be exposed to increased water stress due to climate change. In some countries, yields from rain-fed agriculture could be reduced by up to 50 percent.
-- In Asia, by the 2050s, freshwater availability in Central, South, East and South-East Asia, particularly in large river basins, is projected to decrease.
-- Australia's current drought, which helped spark the country's deadliest bushfire disaster ever in early in 2009, has been linked to climate change. By 2030, water problems are projected to intensify in southern and eastern Australia.
-- Rising sea levels could increase salinity in groundwater and estuaries worldwide. This could have grave implications for coastal urban areas such as Miami, Florida.
(Sources: Intergovernmental Panel on Climate Change, World Health Organization, Pacific Institute for Studies on Development, Environment and Security)
(Reporting by Ed Stoddard, editing by Mary Milliken)