Greenhouse gases, computer illustration. Molecular models of carbon dioxide (left), methane (bottom right) and water (top right). The build-up of these gases in the Earth's atmosphere traps an increased amount of solar radiation and leads to a gradual warming of the whole planet. The gases are a result of industry, the burning of fossil fuels, modern agricultural methods and deforestation. Global warming is expected to cause massive changes in weather patterns and a rise in sea level, due to polar ice melting, that could flood coastal regions. Atoms are represented as spheres and are colour-coded: carbon (black), hydrogen (green) and oxygen (red).