Understanding the causes and potential consequences of global climate change on people and the environment are crucial in implementing strategies to reduce the threat of climate change in the future.
The energy question affects us all deeply, but there is no 'right' view on it. What are the proposed solutions and what is at stake for the different interest groups (eg consumers, politicians, developing and developed countries)?
Many scientists, governments and international bodies - but not all - commonly accept the greenhouse effect and global warming theories. Some argue that the greenhouse effect and the extent to which greenhouse gases contribute to it have both been exaggerated. Some argue that the predicted rises in atmospheric temperatures and sea levels are overestimated.
Environmental campaigners argue that oil companies have contributed to environmental problems. Some activists even claim that wars in the Middle East were influenced by Western governments and oil companies' plans to get access to oil reserves.
On the other hand, many representatives of oil companies and industries that use a lot of energy argue that environmentalists have exaggerated the extent to which fossil fuels pollute the atmosphere and the impact this will have on the environment.
Most governments have promised to reduce greenhouse gases by signing up to the Kyoto Protocol. But the USA - the world's biggest greenhouse gas emitter - refuses to agree to the treaty.
Some groups - environmentalists included - campaign against certain types of alternative energy generation. For example, dams built to produce hydro-electric power flood large areas - impacting on local people, wildlife, vegetation and hydrology. Tidal barrages could alter the look, behaviour and ecology of estuaries such as the Severn, and might cause pollution problems. Some people oppose wind farms on the grounds that they are ugly, noisy and a hazard to wild birds.