Scientists have pushed back the so-called "Doomsday Clock" one minute further away from "the midnight hour", citing hopeful developments in nuclear weapons and climate change for its decision.

The concept timepiece was devised by the Bulletin of the Atomic Scientists and first featured in Time magazine in 1947, shortly after the US dropped its atomic bombs on Japan. The symbolic clock shows how close mankind is to self-destruction. It was set at seven minutes to midnight and has been adjusted 18 times since then.

The previous most recent clock change was in January 2007. It moved to five minutes to midnight, when climate change was added as a further threat to mankind, alongside growing concerns over nuclear weapons. North Korea's test of a nuclear weapon, Iran's nuclear ambitions and a renewed US emphasis on nuclear militarisation were among the doomsday anxieties three years ago.

Scientists say there has been a "shift in world opinion" in the past couple of years and praised US President Barack Obama's role in the "new era" of international co-operation.

Doomsday Clock by alancleaver_2000 (Flickr)