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Home > Geography > International issues > Global warming


Global warming


Energy generation from fossil fuels also produces a build-up of gases - principally carbon dioxide and methane - which is thought to be a major cause of global warming.

Impacts of energy demand: global warming

Map of the Kangia ice fjord, Greenland

Map of the Kangia ice fjord, Greenland.

The greenhouse effect

When fossil fuels are burnt - by industry, in power stations and in vehicles and planes - the gases enter the atmosphere. Although these gasses have always been present in the world's atmosphere, their concentration is gradually increasing as more and more fossil fuels are burnt.

Scientists believe that the build-up of these so-called greenhouse gases in the atmosphere acts like a blanket or greenhouse around the planet; heat is trapped inside the Earth's atmosphere. This is the greenhouse effect, and the resulting increase in global temperatures is called global warming.

How the greenhouse effect works

It's thought that the build-up of greenhouse gases impacts on global temperature in two ways:

  1. The gases allow more of the sun's rays to enter the atmosphere. Some solar radiation is still reflected back into space by the outer parts of the atmosphere, but it's believed the amount reflected back is gradually reducing.
  2. At the same time, the greenhouse gases absorb more of the solar radiation that is reflected back from the Earth's surface - trapping heat and keeping it in the atmosphere. Of course the ability of the atmosphere to capture the sun's warmth is essential for life on earth. But if significantly MORE warmth is being captured, this is bad news for the planet.
World map showing percentage contribution to global carbon emissions by large countries.

Another group of greenhouse gases includes the chlorofluorocarbons (CFCs for short). CFCs have been responsible for depleting the ozone layer as they attack and destroy ozone molecules.

  • The ozone layer is a high level layer of gas in the stratosphere. The ozone helps to keep out harmful ultra-violet rays, which cause sunburn on human skin and damage plants.
  • CFCs have been used in aerosols, such as hairspray cans, fridges and in making foam plastics.
  • The resulting ozone holes let harmful ultra-violet radiation in and adding to the problems of the greenhouse effect and global warming.
  • CFCs were banned in many countries in the mid-1990s after it was found that they were breaking up the Earth's ozone.
  • Scientists say the hole in the ozone layer over Antarctica could disappear within 50 years


The Arctic

Class Clips

Evidence of global warming


James Lovelock

Class Clips

Environmentalist James Lovelock on global warming


The Maldives

Class Clips

Global warmings effect on the Maldives

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