Climate change

The Earth is warmed by the Sun, and loses heat to space. Some of the gases in the atmosphere trap heat and help to keep the Earth warm. These gases include carbon dioxide, methane and water vapour. Without these gases the average temperapture on Earth would be about -18*c. These gases are sometimes called 'greenhouse gases'.

Carbon dioxide
The temperature of the Earth varies naturally over long periods of time. The amount of carbon dioxide in the atmosphere also varies naturally, and this is linked with the temperature changes.

Since 1800 the proportion of carbon dioxide in the atmosphere has increased because humans have been burnning fossil fuels and so releasing carbon dioxide into the atmosphere. Farming also add methane to the atmosphere. Graphs show that the Earth's temperature and the concentration of carbon dioxide have both risen. This is called climate change.

Reducing C02
Chemists are trying to find ways to control the amount of C02 in the Earth's atmosphere. Two methods beeing investigated are:
 * 'seeding' the oceans with iron compunds. This might encourage microscopic plants to grow, which would use carbon in photosynthesis. This carbon would eventually be incorportaed into shells and end up in sediments.
 * capturing carbon dioxide from power stations waste gas and converting it into hydrocarbons to be use as fuels.