The human race can breathe a tiny bit easier (but not too much) now that the Bulletin of the Atomic Scientists has moved the hand of its Doomsday Clock one minute farther away from midnight, the time which symbolizes catastrophic destruction and the apocalyptic end of civilization. The clock now reads six minutes from that end-of-days witching hour after it was changed during a press conference Thursday in New York City, citing an increased awareness and interest in stopping key threats to humanity (in particular nuclear conflict and global warming) since U.S. President Barack Obama took office about a year ago.

But the Bulletin, a group established shortly after World War II by the likes of Albert Einstein and J. Robert Oppenheimer, tempered its actions with the major caveat that humankind could slip closer to oblivion again if the world's governments do not follow through on promises made to curb the creation of more nuclear weapons and greenhouse gases. Although the Bulletin was originally formed out of concern for global nuclear annihilation, the group has since broadened its purview to include the world's vulnerability to climate change.

The Bulletin's members at Thursday's press conference noted that leaders of nations equipped with nuclear weapons have expressed the desire to cooperate in reducing their arsenals and securing nuclear bomb-making material. This includes a shared sentiment between Obama and Russia's President Dmitry Medvedev that nuclear arms negotiations that could bring down deployed strategic warheads from more than 2,000 to about 1,500 each.

One growing challenge to the Bulletin's original mission is that newer generations of policymakers were born into a post–Cold War world with a diminished awareness of the damage that nukes can inflict. One way to ensure that the lesson of Hiroshima and Nagasaki is not forgotten is for the world's nuclear powers (the U.S. and U.K., Russia, France and China) and countries that have tested and/or deployed nuclear weapons (in particular, India, Israel, North Korea and Pakistan) to ratify agreements such as the Comprehensive Nuclear Test Ban Treaty, which the U.S. Senate also has yet to do.

For the first time since nuclear bombs were dropped on Japan 65 years ago, many world leaders are looking for ways to reduce nuclear weapon stockpiles, and they are pledging to curb climate-changing gases that could make our planet uninhabitable, said Lawrence Krauss, co-chair of the Bulletin's Board of Sponsors and director of the new Origins Initiative at Arizona State University in Phoenix. Krauss and his Bulletin colleagues credit Obama's election as a major part of new arms reduction talks with Russia, the now-stalled negotiations with Iran to close its nuclear enrichment program, and the potential of a U.S.-led effort to secure all loose fissile material in four years.

Another factor in the Bulletin's measured optimism is the indication that security threats are more likely to be asymmetrical, coming from decentralized terrorist groups or nations suffering from economic collapse and resource scarcity exacerbated by climate change. In such situations there is no single target (like Washington or Moscow) for nukes, rendering them less effective either as offensive weapons or deterents.

Pervez Hoodbhoy, a Bulletin member and head of Quaid-i-Azam University's physics department in Pakistan, called for a moratorium on the development of materials that go into nuclear weapons and on testing nuclear weapons. He noted that India and his native Pakistan are making fissible material as quickly as they possibly can.

Although the Bulletin was created by scientists, engineers and other experts who had developed the atomic bomb as part of the Manhattan Project during World War II, the group in recent years has turned a good part of its attention to the threats posed by climate change. In fact, nukes and climate change are closely linked given that some see nuclear energy as one way to reduce emissions from burning fossil fuels. The Bulletin acknowledges that the increased use of carbon-free nuclear energy could help mitigate global warming brought on by fossil fuels and greenhouse gas emissions but concludes that the possibility of misusing enriched uranium and separated plutonium to create bombs is a "terrible trade-off" for trying to control climate change.

Stephen Schneider, Stanford University environmental biology and global change professor and member of the Bulletin's Science and Security Board, called climate change a "threat multiplier" at Thursday's press conference. Although climate change did not create the poor conditions for people in Sudan's Darfur, it has made them worse. He pointed out that, regardless of the documents that surfaced as part of the highly politicized "climategate" controversy in December, the evidence for global warming remains. As contemporary signs of global warming, Schneider and his colleagues point to rapidly melting polar icecaps, ocean acidification, loss of coral reefs, longer-lasting droughts, more devastating wildfires, and rising sea level.

Last month's Copenhagen conference was the first time in the 17-year history of U.N. climate conferences that developing and industrialized countries all agreed to take responsibility for emissions, according to a statement issued by the Bulletin. The negotiations in Copenhagen have raised expectations that governments will begin to reduce carbon emissions through regulatory schemes, public and private investments in alternative energy sources, and promotion of energy efficiency. "We can be optimistic that there's an opportunity," Schneider said. "But it will not happen automatically."

Highs and Lows
The last time the minute hand of the Bulletin of the Atomic Scientists's Doomsday Clock moved was in January 2007, when it was pushed forward two minutes (from seven to five minutes before midnight), thanks in part to North Korea's nuclear testing and concerns over Iran's nuclear intentions. Other major movements have included:

  • 3 minutes to midnight: In 1949 President Harry Truman tells the U.S. public that the Soviet Union has tested its first nuclear device, officially starting the arms race.
  • 2 minutes to midnight: In 1953 the U.S. decides to pursue the hydrogen bomb, a weapon even more powerful than the atom bombs used against Japan; soon after, the Soviet Union tests an H-bomb of its own.
  • 12 minutes to midnight: In 1972 the U.S. and Soviet Union sign the Strategic Arms Limitation Treaty (SALT I) and the Anti-Ballistic Missile (ABM) Treaty.
  • 3 minutes to midnight: In 1984 the U.S. and Soviet Union virtually cut off communications, and the U.S. considers building an expansive, space-based anti-ballistic missile system.
  • 17 minutes to midnight: In 1991, with the Cold War officially over, the U.S. and Russia begin cutting their nuclear arsenals. (The minute hand was moved back to 14 minutes in 1995 over concerns that terrorists could obtain weapons from poorly secured nuclear facilities in Russia.)