Over the past 540 million years Earth has suffered five mass extinction events, the worst of which wiped out more than 9 per cent of marine life on the planet. A new study has suggested that the next such catastrophe might not be too far away. Massachusetts Institute of Technology (MIT) geophysicist and mathematician, Daniel Rothman has been busy studying previous mass extinctions. He reckons the next one might be a mere 83 years away. The previous five catastrophic events each unfolded over millions of years and involved the natural cycle of carbon through the oceans and atmosphere being disturbed, resulting, in some cases, the death of almost all life on Earth. The award-winning mathematician identified two "thresholds of catastrophe" that, if exceeded, would upset the natural order of the cycle, leading to an unstable environment and eventually a mass extinction. The first relates to changes in the carbon cycle over a period of thousands or millions of years. A mass extinction will