1 WATER All living things are made mostly of water Humans are about 60 percent water Plants are 80 to 85 percent water And the Earth’s surface is 70 percent water That’s why the Earth is called the blue planet Where Is the Earth’s Water About 97 percent of the Earth’s water is salt water which is found mainly in the seas and oceans It’s too salty to drink or use to irrigate crops Only 3 percent of the water on Earth is fresh water so it is a rare and precious thing We use fresh water to irrigate our farmland and gardens and we also treat it to make it safe to drink or potable
There are almost two hundred countries in the world but nine of them consume more than half of the planet’s available fresh water In the United States and Canada people use a lot of water in their homes About 65 percent of that is in the bathroom for showering in parts of Africa and Asia brushing teeth and flushing the toilet The remaining 35 percent is used for things like cooking drinking and washing clothes Canadians and Americans use much more water than people
Oceans The oceans keep the planet’s climate in balance They absorb and store the Sun’s heat and that heated water sets ocean currents in motion The currents move the heat around the planet like a giant conveyor belt Warm water from the tropics is transported to the poles on the surface of the ocean At the same time cold currents flow in deep water The ocean is home to tiny algae called phytoplankton that are invisible to the naked eye These microscopic algae are carried on the surface waters by the currents and they play an essential role Like green plants they act as small chemical factories Through photosynthesis they absorb much of the carbon dioxide from the atmosphere and release more than half of the oxygen we breathe
The five oceans are the Atlantic the Pacific the Indian the Arctic and the Southern They are all connected creating an immense body of water that is constantly in motion Oceans and the Economy Hundreds of millions of people around the world depend on fishing and aquaculture for their food and their jobs A great deal of international trade is conducted by sea Huge ships transport cargo all over the world Fossil fuels such as coal oil and natural gas make up 40 percent of this cargo which can represent a danger to the environment if an oil tanker sinks pollution from its cargo can be disastrous to ocean waters The ocean is also the source of other activities that have an impact on the economy tourism pleasure boating shipbuilding and offshore drilling for oil and gas On any single day there are more than fifty thousand cargo ships on the world’s oceans One of the biggest container ships in the world the Bougainville is almost the length of four football fields It can carry more than fifteen thousand shipping containers at a time
