Many scientists are predicting global climate change. Water means different things to different people.
All life depends on water.
A person can live without food for more than a month, but can live for only a few days without water. All living things, from the tiniest insect to the tallest tree, need water to survive. There are a number of theories that try to answer this question. Some think water was here from the start. Many scientists believe that 4.5 billion years ago, when the earth was being formed, its primitive atmosphere already contained the basic constituents needed to form water.