The Tibetan Plateau is the highest and largest plateau on Earth — about 2,500 km east to west, 1,000 km north to south, averaging over 4,500 m. The Steppes run over 8,000 km west to east.
Europe
European Plain, the Alps
The European Plain is one of the largest flat lands in the world; the Alps are a 1,200 km crescent-shaped range holding Mont Blanc.
Africa
Sahara Desert, African savannah, River Nile
The Sahara is the largest hot desert in the world (30°C to 46°C, rainfall below 25 cm); the Nile, almost 6,650 km, is the longest river in the world.
South America
Andes Mountains, Amazon River and Rainforest, Atacama Desert
Mount Aconcagua is the highest peak in the Western Hemisphere; the Uyuni Salt Flats are the largest salt flat on Earth; the Amazon is the world’s largest river by volume; the Atacama is one of the driest places on Earth.
North America
Colorado Plateau and Grand Canyon, Rocky Mountains, Appalachian Mountains, Great Lakes
The Rockies stretch over 4,800 km; the Appalachians are among the oldest ranges in the world; the Great Lakes are a chain of five massive freshwater lakes.
Australia
Great Australian Desert (including the Great Victoria Desert), Great Barrier Reef
A whole continent whose interior is arid, fringed by the largest coral reef structure on Earth.
Antarctica
The polar ice continent
The largest desert on Earth — over 14 million square kilometres, more than four times the area of India — and the coldest.
Why it happens: these features are not scattered at random. Three forces put them where they are.
Where plates collide, land is pushed up. The Indo-Australian plate driving into the Eurasian plate raised both the Himalaya and the Tibetan Plateau behind it. The Andes stand along the western edge of South America for the same reason. Old ranges that stopped growing long ago — the Urals, the Appalachians — have been worn down by erosion and are therefore low and rounded, not sharp and snow-capped.
Where air sinks, deserts form. Air heated at the Equator rises, drops its rain there (the Amazon and Congo rainforests), then travels away from the Equator and sinks back near the Tropics. Sinking air warms up and cannot form clouds — so the Sahara, the Arabian and Thar deserts, the Kalahari and the Australian interior all sit in the same two belts, north and south.
Where mountains or distance block the sea, deserts also form. The Gobi lies deep inside Asia, too far from any ocean for moist winds to reach; the Atacama is squeezed between the Andes and a cold ocean current. Between the rainforest belt and the desert belt lies the in-between land — the African savannah, with its distinct wet and dry seasons.
Why the Sahara, the Arabian, the Thar, the Kalahari and the Australian deserts all sit at roughly the same distance from the Equator.
Q2.
Why do we need to understand world geography?
Answer
Because what happens far away decides what happens here. The chapter’s very first page makes the point: the distant Southern Indian Ocean influences the monsoon in the Gangetic Plains — the rain that fills a field in Bihar is set in motion thousands of kilometres to the south.
Four reasons follow from that:
The Earth is one connected system. Dust blown off the Sahara travels all the way to the Amazon, carrying the phosphorus its plants need. The Gulf Stream carries warm water from near the Equator to Western Europe, which is why the United Kingdom is warmer than other places at the same latitude. You cannot explain either place without the other.
Trade and daily life run along geographical lines. The Persian Gulf has carried trade between India and Europe for millennia; the Suez Canal, opened in 1869, cut the sea route from Mumbai to London; bays shelter our ports from the open ocean’s winds. The price of goods in an Indian market still depends on such passages staying open.
Environmental problems ignore borders. Melting permafrost in the far north releases carbon dioxide and methane that warm the whole planet. Cheap clothes discarded in rich countries end up as a mountain of waste in the Atacama. Reef bleaching off Australia is caused by changes in ocean water that no single country produced.
Wise management needs knowledge first. As the chapter’s closing bullet puts it, studying world geography helps us understand these features and the need to manage them wisely for sustainable development. You cannot protect a mountain, a reef or a river basin you do not understand.
Did you know? Tagore’s line at the head of the chapter says the modern age has brought the geography of the earth near to us, but made it difficult to come into touch with man. Knowing the map is only half the job; knowing the people who live on it is the other half.
Q3.
How do human actions trigger environmental issues?
Answer
Almost always in the same way: we take more of something than the system can replace, or we add something the system cannot absorb. The chapter gives several clear examples.
Human action
What it triggers
Where in the chapter
Burning fuels and polluting the sea, changing the chemical composition of ocean waters
Coral bleaching — the coral dies and a whole host of sea animals lose their habitat
Fig. 1.9, p. 8
Overfishing and pollution near reefs
Loss of the ‘rainforests of the sea’ that shelter about one-quarter of all ocean species
p. 7
Deforestation of the Amazon for land and development
Loss of the largest rainforest, of the communities in it, and of the carbon it stores
pp. 24, 31
Global warming caused by greenhouse gases
Permafrost melts and releases the carbon dioxide and methane it had trapped — which warms the planet further
p. 16
Agricultural run-off and industrial processes
Chemical contamination of the sediments and water of the Great Lakes
p. 29
Cheap fast fashion discarded when trends change
One of the world’s fastest-growing clothing dumps in the Atacama — called by the UN ‘an environmental and social emergency’
p. 25
Overgrazing by elk after their predators were gone
Ecological imbalance in Yellowstone — corrected only when wolves were reintroduced in 1995
p. 28
Why it happens: in nature everything is linked, so a push in one place travels. Remove the wolf and the elk multiply; the elk eat the young plants; the plants disappear and with them the soil and the birds. The permafrost example is the most serious kind of link, a feedback loop: warming melts the frozen soil, the melting soil releases gases, and those gases cause more warming. Once such a loop starts, it keeps itself going even if we stop the original push — which is why acting early costs far less than repairing later.
Tip: The Yellowstone story is the hopeful half of the answer. Damage caused by human action can sometimes be undone by human action, if we act on the ecosystem rather than on one animal at a time.