Global water supply: surplus and deficit

你需要知道的

• Earth cannot run out of water because of the water cycle, but very little of it is fresh, liquid and easy to reach.
• About 97% of Earth's water is salty and most fresh water is locked in ice, leaving under 1% in rivers, lakes and groundwater.
• Water is unevenly spread: some regions get little rain, and moving water to them is costly.
• Many places use rivers and aquifers faster than rain refills them, so scarcity is a local problem of overuse.
• Agriculture uses most of the world's water; efficient irrigation, drought-tolerant crops and less food waste reduce demand.

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