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Changes in the environment

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Humans

Humans are very successful living things. We compete with other organisms for many natural resources. These include:

  • land (for farms, buildings and roads)

  • water (for drinking, watering fields, and industry)

Population growth

The world’s population of humans is increasing all the time. In the year 1800 it was about 1 billion, and now it is more than 6 billion (that's 6,000,000,000).

More people mean more use of natural resources, and bigger changes to the environment. The graph shows population growth over the last 200 years.

Graph shows population in billions. The population is steady, at just over 0 billion, until 4000 BCE, when it begins to rise. At around 1000 CE there is a sharper increase, and at 2000 CE the population is 6 billion.

Land use

Humans use machines to move large amounts of earth to make new roads and buildings. We straighten rivers and build walls to stop them flooding. In some countries, such as the Netherlands, land is reclaimed from the sea. Barriers are built and water is pumped out. New dry land forms for people to use.

We also large areas of land for quarries. These are large holes in the ground where rocks containing useful metals are taken out.

The environment is also changed when land is flooded to make reservoirs for drinking water or hydroelectric power schemes. The animals and plants that live in the forest or on the land lose their habitat. They may die out in that region as a result.

Deforestation

Humans have been cutting down trees for thousands of years. We do this to clear land for farming and building, and for wood to use as a fuel or building material.

Forestry is sustainable as long as forests are allowed to replace themselves, or are replanted after felling, but often this is not done. The result is that the world’s forests are steadily shrinking.

The maps below show the loss of forest across the world over the last 10 thousand years.

The world's forests

Map shoes areas of forests, at around 8000 BC.

The world's forests 8000 BC

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