An international group of atomic scientists is warning of the dual threats to the world posed by nuclear weapons and climate change.  VOA's Stephanie Ho reports from Washington.

Kennette Benedict, right, executive director of Bulletin of the Atomic Scientist, along with Lawrence Krauss, left, and Ambassador Thomas Pickering, unveils the 'Doomsday Clock'

Since 1947, the Bulletin of the Atomic Scientists has maintained the so-called Doomsday Clock. The symbolic timepiece measures how close mankind is to midnight, which represents total destruction of the Earth.

Kennette Benedict, the non-profit organization's executive director, announced that the minute hand on the Doomsday Clock is being moved forward two minutes, to five minutes before midnight.

"Not since the first atomic bombs were dropped on Hiroshima and Nagasaki, has the world faced such perilous choices," she said.  "North Korea's recent test of a nuclear weapon, Iran's nuclear ambitions, a renewed emphasis on the military utility of nuclear weapons, the failure to adequately secure nuclear materials, and the continued presence of some 26,000 nuclear weapons in the United States and Russia, are symptomatic of a failure to solve the problems posed by some the most destructive technology on Earth."

She said this time, nuclear annihilation is not the scientists' only concern.

"The dangers posed by climate change are nearly as dire as those posed by nuclear weapons," she added.  "The effects may be less dramatic in the short term, than the destruction that could be wrought by nuclear explosions, but over the next three to four decades, climate change could cause irremediable harm to the habitats upon which human societies depend for survival."

At a joint news conference in Washington and London Wednesday, scientists said they have a responsibility to sound a public warning for people and governments around the world to change their ways.  This point was emphasized by British scientist Stephen Hawking, who is paralyzed and speaks through a computer.

"As scientists, we understand the dangers of nuclear weapons and their devastating effects, and we are learning how human activities and technologies are affecting climate systems in ways that may forever change life on earth," he said.  "As citizens of the world, we have a duty to share that knowledge and alert the public to the unnecessary risk that we live with every day."

The minute hand on the Doomsday Clock was last changed in February 2002, when it was also symbolically moved closer to midnight following the September 11, 2001, terror attacks in the United States.