Scientist Stephen Hawking is seen during a press conference on the Doomsday Clock, a symbol of the risk of atomic cataclysm. ((Lewis Whyld/Associated Press))

The face of the Doomsday Clock shifted two minutes closer to midnight Wednesday, symbolizing the impending destruction of humanity in a "Second Nuclear Age."

Chicago's Bulletin of the Atomic Scientists, the group that has maintained the timepiece since 1947, wound the minute hand closer to the grim hour for the first time since 2002, when it was frozen at seven minutes to midnight.

Now modern dangers such as global warming and the nuclear ambitions of Iran and North Korea have inched the clock two minutes forward — to five minutes to midnight.

Created in 1947

"The major new step reflects growing concerns about a 'Second Nuclear Age' marked by grave threats," including nuclear programs in North Korea and Iran, as well as continuing "launch-ready status" of 2,000of the25,000 warheads held by the U.S. and Russia, the scientists said in a statement Tuesday.

The world has used the Doomsday Clock as a measurable way to reflect the perils facing humanity since it was created in 1947. In its first year, the minute hand perched at seven minutes to midnight, and it has edged closer with each worsening nuclear and climate threat, or backwards to indicate more secure times.

Notably, Doomsday was two minutes to midnight — its closest ever to doom — during the Cold War in 1953, when the U.S. and Soviet Union began testing H bombs.

Renowned physicist Stephen Hawking joined the Chicago-based scientists Wednesday to announce the clock-face change and speak on the nuclear and climate risks facing the world.