Five ways the world could end

They look at some of the most popular doomsday theories and examine whether these five natural phenomena could end the world as we know it - or whether they are just pure science fiction.

1. Meteorites and asteroids

Giant pieces of rock falling from space made exciting plots for '90s sci-fi movies like 'Armageddon' and 'Deep Impact'.

An asteroid dubbed 'Apophis', estimated to be the size of two football fields, could collide with Earth as early as 16 April 2036 if a change in gravity causes it to fall out of its orbit. While they admit it is theoretically possible for the asteroid to hit Earth, they note that the chances are remote; in fact, they put the odds at one in 233,000. If it does strike, our planet will face a continental disaster and major climate change. And if the asteroid falls into an ocean, the disaster could assume global proportions."

2. Solar storms

Powerful solar storms exactly like the ones the world has been witnessing in the last few weeks occur once every eleven years as the sun's magnetic field flips over. 'Solar Cycle 24' has been building gradually with the number of sunspots and solar storms set to reach a 'solar maximum' by 2013. Super solar flares send great geysers of hot gas and huge quantities of charged particles erupting from the surface into space. These flares of charged particles, called 'coronal mass ejections', slam into the Earth's magnetic shield impairing electrical devices in their path.

Solar flares would end the world is a little drastic. But in terms of affecting us as humans, it is very damaging to our lifestyles; it can destroy communications that we are very dependent on, like power lines and GPS satellites.

3. Pole shift

According to some modern astronomers and an ancient Mayan prophecy, on the winter solstice of 21 December 2012, Earth will be in exact alignment with the sun and the centre of the Milky Way galaxy - an extraordinary event which happens once every 25,800 years. No one knows exactly what effect this alignment will have on Earth, but the Mayans believed that the consequences of the inter-galactic occurrence would be catastrophic, prompting the world's end. It is imagined that a magnetic field effect reversal will take place, where the entire mantle of the earth would shift in a matter of days, changing the position of the North and the South Pole. Such a rapid change in the Earth's dynamics would result in earthquakes, tsunamis, global climatic change and eventually the ultimate planetary disaster, similar to the one depicted in the disaster movie '2012'.

4. Super volcano eruptions

Last year's eruption of Eyjafjallajokull in Iceland brought air travel across Northern Europe to a virtual standstill, but if one of the largest known super volcanoes was to blow, it could cause a global disaster of biblical proportions. According to volcanologists, the last super volcano to erupt was Mount Toba in Sumatra, Indonesia, 75,000 years ago.

Now international scientists speak about the possibility of a future eruption of one of the largest known prehistoric volcanoes - the Yellowstone caldera in Wyoming, which sits above a large magma chamber and is showing more signs of activity. Observers say that an eruption would result in a mega disaster coating half the US in a layer of ash up to one metre deep, killing livestock and putting thousands of human lives at risk. Scientists say that it typically erupts every 600,000 years, but the last eruption occurred 640,000 years ago, meaning the next one is long overdue.

5. Global warming

Should the Earth's average temperature continue to rise at the rate it has done over the last 50 years, the face of the Earth as we know it will change, say climatologists.

London will be as hot as Cairo with air quality so poor it would endanger human respiratory systems. The world's most populous low-lying cities like Tokyo, New York, Mumbai, Shanghai and Dhaka will be engulfed by floods after an eleven-metre rise in sea levels. Extreme weather events, like hurricanes and droughts will become more common, with climate change spreading more infectious diseases.