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LET'S EXPLORE The Earth

What is causing global warming?

Melting icebergMelting icebergThe Earth is getting warmer. Average temperatures worldwide have risen during the last century and there is no sign of this rise slowing. There is now a high risk that the polar ice caps will start to melt, raising sea levels everywhere and changing world climates.


Diagram of the greenhouse effectDiagram of the greenhouse effect

Greenhouse effect

The atmosphere contains gases that stop all the Sun’s heat escaping. These gases act like the glass in a greenhouse. They help keep the Earth’s surface warm. This is called the greenhouse effect.

Global warming is caused by the greenhouse effect. Human activities have resulted in a large increase of greenhouse gases, such as carbon dioxide, in the atmosphere.

Vehicles and power stations give off exhaust gases from burning oil or coal (“fossil fuels”). These add billions of tonnes of carbon dioxide to the atmosphere. Plants will usually absorb (take in) carbon dioxide as part of their natural life cycle. But the destruction of forests around the world means there are fewer plants to absorb the gas.

Emissions that increase greenhouse gasesEmissions that increase greenhouse gases

Effects

The ice shelves of West Antarctica are so vast that, if they melted completely, the water released into the ocean would cause sea levels to rise up to 3 metres (10 feet).

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