Final answer:
Tokyo is already rationing water supply due to water scarcity, which is a global issue that is expected to worsen. The shortage of water can have significant impacts on various aspects of life.
Step-by-step explanation:
Tokyo is experiencing water rationing due to water scarcity. The increasing global water shortage is expected to affect more than half of the world's population by 2025, as predicted by estimates. Water shortages can lead to various problems, including insufficient supply for drinking and agriculture.