Chemical changes to the atmosphere are creating four main sets of problems.

You may have heard about two of them:

• global warming (or climate change), and
  
  

• ozone depletion

These are two quite separate phenomena caused, on the whole, by different chemicals.

The third - acid rain - is more regional, while the fourth, VOCs and ozone, is much closer to home.

Climate Change

Climate change will affect the whole world. In the last 100 years various activities have increased the amounts of gases that trap the heat of the earth.

About half of the global warming is due to carbon dioxide (CO2). Burning fossil fuels (coal, oil, and gas) produces carbon dioxide.

As more forests are cleared and burnt, the earth loses its "lungs", and therefore loses its capacity to absorb this gas back.