A desert is a region with less than 250 mm of rainfall a year. Deserts cover about one-fifth of the Earth’s land; they can be hot (the Sahara, the Kalahari, the Kyzylkum) or cold (Antarctica). There is little vegetation because the climate is dry. The Aral Sea, between Kazakhstan and Uzbekistan, has become much smaller since the 1960s. Problem: the sea is drying up. Cause: a lot of water from the Amu Darya and the Syr Darya was taken to irrigate cotton and other crops. Effect: fishing has declined and salty dust from the dry seabed harms people’s health. Solution: save water, use drip irrigation and plant saxaul trees on the dry seabed. Say it with must and should: “We must save water.”
Worked examples
The Kyzylkum is a sandy desert in Uzbekistan. Summers are very hot and the winters are cold. Camels, lizards and saxaul bushes can live there because they need little water.
Problem – the Aral Sea is shrinking. Cause – too much water was taken from the rivers. Effect – the land is dry and salty dust spreads. Solution – we should save water and plant saxaul trees.
Class activity
“Desert life”: groups find three desert animals and three plants and explain why they can live with little water.
Practice
1
Define a desert.
A desert is a region with very little rain, less than 250 mm a year.
2
What is the cause of the Aral Sea problem?
Too much river water was taken to irrigate fields.
3
Write a solution with must or should.
We must save water and plant trees.
4
Why is there little vegetation in a desert?
There is little rain and the air is dry, so plants lack water.