An asteroid just half a mile wide could unleash a mini ICE AGE if it hits Earth

The impact would throw up dust and soot into the atmosphere that would causing average temperatures around the world to fall by as much as 8°C.

Scientists have warned the 'very severe global impact' would last several years, causing the world to become a much darker, colder and drier place.

'These would not be pleasant times,' Charles Bardeen, of the National Center for Atmospheric Research said in December during a presentation at the American Geophysical Union (AGU).

Bardeen and his team believe the impact would create a 9 mile (15 km) wide crater, throwing massive amounts of dust into the atmosphere, according to a report in Space.com.

If the strike doesn't occur in a desert, the impact would also produce huge fires that would release soot into the air.

In the 'worst case scenario', soot would remain in the atmosphere for around 10 years, while dust take six years to settle back on Earth.

This would reduce the amount of sunlight hitting Earth's surface by around 20 per cent for the first few years, Bardeen believes.

As a result, average global surface temperatures would cool by 8°C (14.5°F) 'which is about the equivalent of the ice ages', he said.

And Bardeen claims the top layers of the ocean would still be about 0.5°C (0.9°F) cooler than normal 15 years after the asteroid impact.

The global cooling would also lead to a drop in rainfall of about 50 per cent.

'This is due to the lost heating and the lost temperature, so we lose convection; we don't have as many [weather] fronts,' said Bardeen.

Meanwhile, with the planet blanketed, chemical reactions that damage the ozone layer would be speed up.

As a result, atmospheric ozone would be reduced by 55 per cent, causing the surface UV index to top 20 in the tropics for a number of years.

To cause a mass extinction, however, the asteroid impact would have to be 10 times bigger.

In September, Paul Chodas, manager of Nasa's Near-Earth Object office at the Jet Propulsion Laboratory in Pasadena, said: 'There is no existing evidence that an asteroid or any other celestial object is on a trajectory that will impact Earth.

'In fact, not a single one of the known objects has any credible chance of hitting our planet over the next century.

Nasa tracks around 12,992 near-Earth objects which have been discovered orbiting within our solar system close to our own orbit.

It estimates around 1,607 are classified as Potentially Hazardous Asteroids. 

Last week, Nasa announced that a 100ft-wide asteroid, first spotted when it flew by Earth two years ago, set to make its return on 5th March – and this time it could get incredibly close.

The whale-sized space rock may skim past Earth at just 11,000 miles (17,000 km), which is around 21 times closer to Earth than the moon.

But Nasa admits this estimate may be widely inaccurate, and the asteroid may also pass Earth as far out as 9 million miles (14 million km).

In both scenarios, the space agency says the asteroid, dubbed 2013 TX68, poses no threat to Earth.

(http://www.dailymail.co.uk/sciencetech/article-3439283/An-asteroid-just-half-mile-wide-unleash-mini-ICE-AGE-hits-Earth-Impact-reduce-temperatures-8-C.html)