It's well known that carbon dioxide is a greenhouse gas, but just what does this mean, and what are the possible consequences of global warming?

Radiation from the Sun heats Earth's atmosphere, oceans and land, making life on Earth possible. The incoming radiation can easily pass through the outer atmosphere in order to reach the Earth, but much of it cannot escape as the atmosphere acts as a one way valve. Exactly how much of the radiation escapes the atmosphere depends on the concentration of greenhouse gases (including carbon dioxide, methane etc) present. However, the so-called greenhouse effect is not a bad thing as such - without it, the temperature of the surface of the Earth would be -18°C, instead of the actual value of about 15°C. So what's all the fuss about?

The main worry is that, as previously mentioned, the amount of radiation which escapes depends on the concentration of greenhouses gases in the atmosphere - carbon emissions add to the concentration, meaning that less radiation escapes. This means that the surface temperature of the Earth increases - by 0.6°C ± 0.2°C over the last century. This may not sound like much, but the warming will increase with time, and could have disastrous consequences. These might include: