Global uncertainty on how to deal with the threats of nuclear weapons and climate change have forced the "Doomsday clock" one minute closer to midnight, leading international scientists said on Tuesday.
"It is now five minutes to midnight," said Allison Macfarlan, chair of the Bulletin of Atomic Scientists, which created the Doomsday clock in 1947 as a barometer of how close the world is to an apocalyptic end.
The last decision by the group, which includes a host of Nobel Prize winning scientists, in 2010 moved the clock a minute further away from midnight on hopes of global nuclear cooperation and the election of President Barack Obama.
However, Tuesday's decision pushes the clock back to the time where it was in 2007.
"It is clear that the change that appeared to be happening at the time is not happening," said co-chair Lawrence Krauss. "Business as usual reigns the norm among world leaders."
Increasing nuclear tensions, refusal to engage in global action on climate change, and a growing tendency to reject science when it comes to major world concerns were cited as key reasons for the latest tick on the clock.
The nuclear accident at Japan's Fukushima plant also highlighted the volatility of relying on nuclear power in areas prone to natural disasters, scientists said.
Robert Socolow, a member of the BAS science and security board and professor of mechanical and aerospace engineering at Princeton University, said a common theme emerged in the scientists' talks on how to move the clock.
He cited a "worrisome trend to reject or diminish the significance of what science says is the characteristic of a problem," and called for better world political leadership that accepts the role of science.
"The world is in a pickle," he added. "More people want to live better than they live now on a planet of finite size."
The group added it was "heartened by" a series of world protest movements, including the Arab spring, the Occupy demonstrations in the United States and protests in Russia which show people are seeking a greater say in their future.