World Geography: Some Glimpses

The oceans, currents, trenches and coral reefs, why every map projection distorts, and key landforms of every continent.

Key ideas

The ocean covers about 71% of the Earth and holds about 97% of its water.
Oceans give almost half our oxygen through plankton, store heat and bring rain.
Coral reefs shelter about a quarter of ocean species, but overfishing, pollution and warming cause bleaching.
A warm current, the Gulf Stream, keeps the United Kingdom milder than other places at its latitude.
A curved Earth cannot be shown flat without stretching, so every map distorts something.
A gulf is a large inlet of the sea; a strait is a narrow channel joining two seas.
Melting permafrost in the tundra releases gases that speed up climate change.

Remember

Largest, deepest ocean / smallest	Pacific / Arctic
Deepest trench	Mariana Trench
Suez Canal	1869: Red Sea to the Mediterranean
Third Pole	the Tibetan Plateau
Europe–Asia boundary	the Ural Mountains
Deserts	largest hot: Sahara; largest and coldest: Antarctica
Mercator projection	keeps shapes and directions; Greenland looks as big as Africa

Watch out

Believing the Mercator map shows true sizes: lands near the poles look far too big.
Mixing up a gulf and a strait.
Thinking a desert must be hot: Antarctica is the largest desert.

Worked example

A region of 71,000 square km is drawn on a map. (a) If it matched the Earth’s 71% ocean share, how much would be ocean? (b) How much land? (c) Give two ways oceans help life on Earth.

Working: 71% and 29% of 71,000

Answer: (a) 50,410 square km (b) 20,590 square km (c) They give much of our oxygen through plankton and control climate by storing heat and bringing rain.