global warming

Back to SCIENCE main page

Photo of industrial chimneys belching ourt heat, pollution and carbon dioxide   Photo of iicebergs shrinking due to global warming  
Factories and power stations that burn fossil fuels increase global warming (Photo: B Forster - Stone/Getty Images)
Icebergs are breaking up and melting due to global warming

For thousands of years, the concentration of carbon dioxide in the atmosphere remained much the same. But during the past 200 years it has increased steadily.




Graph showing how the percentage of carbon dioxide in the atmosphere has incresed since the year 1700The rise in atmospheric carbon dioxide has been caused largely by:

  • burning increasing amounts of fossil fuels as an energy source, and
  • burning forests to clear land.

Burning forests has two unfortunate effects:

  • the burning wood releases carbon dioxide, and
  • there are fewer trees left to photosynthesise and remove carbon dioxide from the air.

Graph showing the upward trend of global average temperature since 1860As the concentration of carbon dioxide in the atmosphere has increased, so have mean global temperatures. This is called global warming.

Effects of global warming

Global warming could cause:

  • climate change
  • extreme weather conditions in some areas
  • rising sea levels.

Climate change may make it impossible to grow certain food crops in some regions. Melting polar ice and the thermal expansion of seawater could cause rising sea levels and the flooding of low-lying land.

[ This page has been adapted from ]