Members of the Bulletin of the Atomic Scientists announce a movement of the hands on their "Doomsday Clock," a symbolic indicator of the approach of a potential apocalypse. (Rachel Morello/Medill)

WASHINGTON— It may not be time to head for the fallout shelters, but the Bulletin of the Atomic Scientists thinks it’s at least time to pre-emptively sound an apocalyptic alarm.

The Bulletin on Tuesday moved its Doomsday Clock, a symbolic measure of the world’s perceived distance from the apocalypse, one minute forward to 11:55 p.m.  This move suggests that the world is one step closer to total destruction, signified in the model as midnight.

“Two years ago, there was tentative evidence that things were improving, with for the first time perhaps a global approach to global problems,” Lawrence Krauss, co-chair of the group’s Board of Sponsors, said at a news conference announcing the move.  “But in spite of some progress on tactical nuclear weapons and the START treaty, it’s clear that the change that appeared to be happening is not materializing.  Faced with the clear and present dangers of nuclear proliferation, climate change, and the continued challenge of finding new, sustainable and safe sources of energy, business as usual remains the norm among world leaders.”

The Doomsday clock was created after World War II, when the inaugural clock was positioned at seven minutes until midnight in 1947 by a group of scientists who had helped create the atomic bomb.  The group says it wants to warn policymakers and the public about the dangers of nuclear proliferation and climate change.

Krauss and other Bulletin members said that their decision stemmed from deepening concerns on nuclear proliferation, specifically the failure of eight key countries, including the United States, to ratify the Comprehensive Test Ban Treaty to ban all nuclear explosions.  The Bulletin also cited projections from the International Energy Agency that a failure to shift towards reliance on alternative energy could lead to devastating results such as water scarcity, famine and the acidification of oceans.

“We have challenges to our atmosphere, to our forest, to our oceans, to our political systems and to our values, which will be incredibly challenging for the rest of the century and further,” said Robert Socolow, a member of the Bulletin’s Science and Security Board. “To imagine that we will try to find our way without [using science] is quite terrifying.”

The group had specific recommendations for world leaders, including the ratification of the Comprehensive Test Ban Treaty, a commitment to global oversight of civilian nuclear energy and a global reinvestment into the development of alternative energy sources and storage.

The Bulletin last changed the clock in 2010, when it was moved one minute backwards to 11:54 p.m. The reasons: a nuclear nonproliferation treaty between the United States and Russia as well as global efforts to reduce carbon emissions.

When the United States announced a successful test of its hydrogen bomb in 1953, the clock was moved to two minutes until midnight, the closest to midnight in the clock’s history.