Exploring Society II · Chapter 1 — World Geography: Some Glimpses

Try this at home. Peel an orange carefully and press the peel flat on a table. It splits and tears, because a curved skin can never lie flat without breaking. Map-makers face the same problem with the Earth, and that is where this chapter begins.

The shape of the Earth. The Earth is not a perfect ball. It is an oblate spheroid: nearly round, but bulging a little at the equator and slightly flattened at the poles because it spins. A person who draws or produces maps is called a cartographer.

Map projections. Showing the curved Earth on a flat page is called a map projection. Because the orange-peel problem cannot be avoided, every world map has some distortion. Some projections keep the shapes of countries correct but get their sizes wrong; others keep sizes correct but stretch the shapes. Every map is a compromise.

A famous example. On a Mercator map, Greenland looks larger than India. In reality Greenland is smaller than India. It only looks huge because it lies far north, where the Mercator projection stretches everything. So to understand the world fairly, we should compare more than one projection.

The colour language of physical maps. A physical map shows natural features. It uses colours in a fixed way:

• Blue: water bodies such as oceans, seas, lakes and rivers.
• Green: plains. Yellow or brown: plateaus. Dark brown: high mountains.
• Light yellow: deserts. White: ice and glaciers.

Precise location. A world map is good for getting a feel for size, shape and distance. For exact work, professionals use latitude and longitude, the grid of lines you met in Grade 6, because a pair of coordinates fixes a place exactly whatever projection is used.

Seen from space, the Earth looks blue. Early astronauts called it the blue planet, and the reason is simple: the ocean, a vast body of salt water, covers about 71 per cent of the Earth's surface.

What the oceans do for us.

• They store water. The oceans hold about 97 per cent of all the Earth's water.
• They give us oxygen. Oceans provide almost half the oxygen we breathe. Tiny floating organisms called plankton, which have chlorophyll and make food from sunlight and carbon dioxide, do most of this work.
• They control climate. Oceans soak up heat, release it slowly, and add moisture to the air, which forms clouds and rain. Even the distant southern Indian Ocean affects the monsoon rain in the Gangetic Plains.
• They support life, from microscopic plankton to the blue whale, the largest mammal, which can be over 30 metres long and weigh almost 150,000 kg.

The ocean floor is not flat. Like the land, it has mountains, valleys and plains.

The five oceans. You met them in Grade 6. Each has its own character:

Think about it. If pollution harmed plankton so that they made less oxygen, every breathing creature on land would feel it, not just sea life. This is why ocean pollution is a problem for the whole planet and not only for coastal people.

A simple way to remember. Oceans are the Earth's water tank (they hold most of the water), its lungs (they make much of the oxygen) and its heater and air-conditioner (they store heat and spread moisture).

The oceans never stand still. Ocean currents are like giant rivers flowing through the sea. There are two kinds:

• Warm currents carry warm water from the equator towards the poles.
• Cold currents carry cold water from the poles towards the equator.

Currents change climate. The Gulf Stream is a warm current. It flows north from near the equator through the Atlantic Ocean towards western Europe. Because of this warm water, places such as the United Kingdom are warmer than other places at the same latitude. So two towns equally far from the equator can have very different winters, depending on the current offshore.

Ocean trenches. The seafloor has very deep, V-shaped hollows called trenches. The deepest is the Mariana Trench in the Pacific. Its deepest part, the Challenger Deep, is over 11,000 metres below sea level, more than 2,000 metres deeper than Mount Everest is high. Down there it is near-freezing, pitch dark and the water pressure is enormous. Yet life exists. With no sunlight, food cannot be made by photosynthesis; instead some living things use energy from chemicals in the water. Scientists have even photographed a kind of snail there that feeds on such bacteria.

Coral reefs. A reef is a ridge at or near the sea surface. Some reefs are rock; others are built by tiny sea animals called corals. Reefs give food and shelter to about one-quarter of all ocean species, which is why they are called the rainforests of the sea.

The Great Barrier Reef, off the north-eastern coast of Australia, stretches over 2,000 km and covers about 350,000 square kilometres. It houses hundreds of kinds of coral and thousands of kinds of fish, and it is a UNESCO World Heritage Site. It is so large that it can be seen from space.

Threats. Reefs suffer from overfishing, pollution and climate change. When the chemistry of sea water changes, largely because of human actions, corals lose colour and die; this is called coral bleaching. A dead reef means lost homes for a whole host of sea animals.

Oceans are not one smooth sheet of water. Along the coasts they break up into smaller shapes, and geographers give each shape a name. Learning these names helps you read a map and understand trade routes.

How to tell a gulf from a bay. Both are inlets, but a gulf usually pushes deep into the land with a narrower mouth, while a bay is broader and more open. Do not worry if real names do not always follow this rule; the Bay of Bengal, for instance, is the world's largest bay.

Why these shapes matter for trade.

• Gulfs can be ancient trade highways. The Persian Gulf has linked India with Europe for thousands of years.
• Bays give safe places for ports and dockyards, shielding ships from the strong winds of the open ocean.
• Straits are short cuts and also choke points; ships crowd through them.
• Canals are built to save distance.

The Suez Canal. Opened in 1869, the Suez Canal is a human-made passage joining the Red Sea with the Mediterranean Sea. It created a waterway from the Indian Ocean to Europe. Before it was built, ships sailing from India to Europe had to go all the way around Africa. The canal made it the shortest sea route between India and Europe.

The Bay of Bengal. This is India's eastern sea. It has been important for trade for centuries, it shapes the climate of the land around it, and it is home to a great variety of plants and animals.

Reading a map. When you see a long thin ribbon of blue between two pieces of land, think strait. When you see a straight line of water cutting across land, think canal. When the sea bites into the land, think gulf or bay.

Our tour of the land begins near home, in Asia. Recall from Grade 6: mountains rise far above their surroundings with steep slopes; a plateau is raised land with a fairly flat top; plains are wide flat lands; deserts are very dry, and can be hot or cold.

The Tibetan Plateau: the roof of the world. North of the Himalayas lies the highest and largest plateau on Earth. It was pushed up when the Indo-Australian and Eurasian tectonic plates collided, the same collision that raised the Himalayas. It is about 2,500 km from east to west and 1,000 km from north to south, with an average height of over 4,500 metres. Great rivers such as the Indus, the Brahmaputra and the Yangtze start here. Scientists call it the Third Pole because it holds the largest store of fresh water outside the polar regions. As the climate warms, melting snow has made old lakes grow and new lakes appear.

The Gobi Desert. A desert gets less than 25 cm of rain a year. Deserts cover about one-fifth of the Earth's land, and around one billion people live in them. The Gobi lies in Mongolia and north China. Mongolia is called the Land of the Eternal Blue Sky because it has 8 to 9 months of sunny weather, yet winter can fall to minus 30°C. Herders move their animals with the seasons. Today the Gobi's sun and wind are used for solar and wind power.

The Eurasian Steppes. A steppe is a huge flat grassland without forest, with hot summers, cold winters and moderate rain. The Steppes run for over 8,000 km from west to east. They act as a carbon sink, storing carbon from the air underground, and they give resting places to migratory birds such as the Siberian crane. Nomads here traditionally live in round tents called yurts.

The Ural Mountains. Mountains act as water towers, since melting snow and glaciers feed rivers below. The Urals, an ancient range about 2,500 km long, run from the Arctic Ocean to the border of Kazakhstan and form a natural boundary between Europe and Asia. They hold iron ore, copper, gold, coal, oil and gas. Coniferous taiga forests cover much of them, and in the far north lies the tundra, a treeless plain on frozen soil called permafrost. Permafrost traps greenhouse gases; as it melts with global warming, it releases them and speeds up climate change.

Flying west across the Urals we reach Europe, and then turn south to Africa.

The European Plain. Plains are wide flat lands built up by sediment laid down by rivers. Their fertile soils support farming, trade and many people. The Great European Plain is one of the largest flat lands in the world and covers parts of many countries. Its rich soils grow wheat, barley, rye and potatoes; Europe produces the largest share of the world's wheat. Rivers carry goods, and there are deposits of coal, oil and natural gas. Flat land and a pleasant climate helped big cities grow, such as Moscow, Berlin, Paris, Amsterdam and Warsaw. Because it is so valuable and easy to cross, the plain has also been the scene of many battles.

The Alps. South-west of the plain rises a crescent-shaped range about 1,200 km long, the Alps, with famous peaks such as Mont Blanc. Forests change with height: oak and beech low down, spruce and pine higher up, and alpine flowers such as edelweiss near the top. Ibex, marmots, golden eagles and wolves live there. The Alps feed rivers such as the Rhine and tributaries of the Danube, which give drinking water, irrigation and hydroelectric power to lowland Europe.

The Sahara. Africa holds the Sahara, the largest hot desert in the world. Temperatures range from about 30°C to 46°C, rain is below 25 cm, and plants are few. Life adapts: an oasis is a patch with water and date palms; the fennec fox's large ears lose heat; some homes are built underground to stay cool in summer and warm in winter. Nomadic tribes herd sheep, goats and camels, and old trade routes carried gold, salt and ideas across the desert to the Mediterranean world.

The savannah. South of the desert lies the savannah, a tropical grassland with scattered trees and a clear wet season and dry season. Elephants, lions, zebras and giraffes depend on its grass and waterholes. Farming, deforestation and climate change now threaten it.

The Nile. The Nile, almost 6,650 km long, is the longest river in the world. Its valley was the cradle of ancient Egyptian civilisation. For thousands of years it has watered crops such as wheat, barley and flax, and it still gives drinking water, fish, hydroelectric power and a transport route.

Across the Atlantic lie the two Americas.

The Andes. Along the west coast of South America run the Andes, the continent's largest mountain range. They hold Mount Aconcagua, the highest peak in the Western Hemisphere, and Bolivia's Uyuni Salt Flats, the largest salt flat on Earth. The Andes feed great rivers, including the Amazon, the world's largest river by volume. Only about one-quarter of their original plants and animals remain, so the Andes are a conservation hotspot. They are also rich in copper, zinc, silver and lithium.

The Amazon Rainforest. The Amazon flows east from the Andes in Peru to the Atlantic, and its basin supports the Amazon Rainforest, often called the Lungs of the Earth. Almost 400 indigenous communities live there and help protect it. Curiously, dust blown all the way from the Sahara brings phosphorus that its plants need. Deforestation and climate change now threaten it.

The Atacama Desert. In Chile lies the Atacama, about 1,000 km long and one of the driest places on Earth; it is 40°C by day and 5°C by night. Its clear skies are perfect for stargazing, and NASA has tested rovers on its Mars-like rocks. Sadly, it has also become a fast-growing dump for clothes thrown away because of cheap fast fashion.

North America. Four features stand out:

• The Colorado Plateau covers over 3,30,000 square km in the south-western United States. Layers of rock were slowly lifted up and then cut by the Colorado River, making the Grand Canyon, which gets about 5 million visitors a year.
• The Rocky Mountains stretch over 4,800 km and are rich in copper, gold and silver. Native Americans lived there and held the mountains sacred. In Yellowstone National Park, too many elk were eating the plants; wolves were brought back in 1995, the elk numbers fell, and the plants recovered. This is ecosystem restoration.
• The Appalachians are among the oldest mountains in the world and gave coal, timber and gas; the Cherokee are one community native to them.
• The Great Lakes are five huge freshwater lakes used for shipping and drinking water, now troubled by chemical and farm pollution.

Our last stop is Australia, and then we look back at what the whole tour teaches.

The Australian deserts. A large part of Australia is dry, and together these areas are called the Great Australian Desert. It includes several deserts, among them the Great Victoria Desert. Reptiles, skinks, wallabies and bilbies live here, along with feral camels, whose ancestors were brought from places like India and Afghanistan in the 19th century to help exploration. Some rare animals, such as the marsupial mole, are struggling to survive. The Spinifex people, an indigenous group, have lived in this desert for over 25,000 years, and younger generations are keeping their culture alive.

Cold deserts too. A desert is defined by low precipitation, not heat. The largest desert on Earth is Antarctica, covering over 14 million square kilometres, more than four times the area of India. It is also the coldest desert, colder even than the Arctic.

What the tour teaches.

• Nature shapes the surface. Tectonic movement, erosion and deposition build mountains, plateaus, plains, deserts, grasslands and ocean floors.
• Features shape life. They decide climate, which plants and animals live where, and where people farm, settle and trade.
• People now shape features too. Deforestation, overuse of resources and pollution cause problems such as desertification, loss of biodiversity and climate change.

Connections across the globe. Many examples in this chapter cross borders: the southern Indian Ocean affects the Indian monsoon, Sahara dust feeds the Amazon, melting Tibetan snow changes rivers in many countries, and fast-fashion waste from far away ends up in Chile. A problem in one place can become a problem for everyone.

Why study world geography? Knowing how the world's features work helps us manage them wisely, a goal called sustainable development: meeting today's needs without spoiling the Earth for future generations. Restoring Yellowstone and protecting coral reefs show that wise action can repair damage.