Burning fossil fuels releases carbon dioxide. Carbon dioxide is described as a ‘greenhouse’ gas, because it traps heat in the atmosphere. The presence of some greenhouse gases keeps the Earth at a temperature of approximately 15°C, which allows life to survive. A recent increase in the use of fossil fuels has caused the levels of carbon dioxide in the atmosphere to increase, too. More carbon dioxide means that more heat is trapped, and this has caused the average global temperature to rise. This is called global warming.
The effects of global warming are uncertain, but it is likely that the increasing temperatures will disrupt climates around the world, causing some regions to have lower rainfall and other regions to have more. The warmer temperatures will cause ice caps and glaciers to melt, which, combined with the expansion of water in oceans, will cause sea levels to rise, flooding low lying areas which are heavily populated. Extreme weather events such as droughts and storms could also become more common.