Climate Change

Features of climate change

Evidence of climate change

The greenhouse effect

When fossil fuels are burned, for example by industry, in power stations and in vehicles and aeroplanes, gases are released which enter the atmosphere. Although these gases have always been present in the Earth's atmosphere, their concentration is gradually increasing as more and more fossil fuels are burned.

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

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 is believed that the amount reflected back is gradually reducing.

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.

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 ultraviolet 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 ultraviolet radiation in and add 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.