The Doomsday Clock in 2002, when it was set at 11:53. Photograph by Tim Boyle / Getty

In 1947, the Bulletin of the Atomic Scientists published, on its cover, a “Doomsday Clock.” The clock was designed to represent the existential threat to humanity posed by nuclear weapons. That year, it was set at 11:53, or “seven minutes to midnight.” In 1953, following American and Soviet tests of the hydrogen bomb, the clock reached 11:58, or two minutes to midnight (the closest to doomsday it’s ever been). At the end of the Cold War, in 1991, it was turned back to 11:43, or seventeen minutes to midnight (its furthest from doomsday). In total, in the past sixty-nine years, the clock has been changed twenty-two times, giving the world an easy way to gauge the likelihood that our species will destroy itself.

I am privileged to chair the Bulletin’s Board of Sponsors, a group of scientists, including sixteen Nobel laureates, that was created by Albert Einstein and Robert Oppenheimer after the Second World War to advise the Bulletin. As a result, I also work with the Bulletin’s Science and Security Board, which, each year, decides on the position of the Doomsday Clock. It’s a difficult task. Many disparate, worldwide factors must be judged in order to realistically assess the total existential risk facing humanity. This task has become even more complex in the past decade because the Bulletin has begun to explore issues beyond nuclear weapons, including climate change, bioterrorism, and cyber threats. Last year, in January, 2015, the Bulletin set the Doomsday Clock at three minutes to midnight. In a statement, we wrote that “Unchecked climate change, global nuclear weapons modernizations, and outsized nuclear weapons arsenals pose extraordinary and undeniable threats to the continued existence of humanity.”

This year, we’ve decided not to move the clock either forward or backward. It will remain set at 11:57—three minutes to midnight. The fact that the clock’s hands aren’t moving isn’t good news. It’s an expression of grave concern about how the global situation remains largely the same. The last time the clock was this close to midnight was in 1983—the height of the Cold War.

Since we moved the clock forward, a year ago—in 2012, it was set at 11:55— developments have been mixed. There has been some positive news, such as the Iran nuclear agreement and the Paris climate accord. At the same time, nuclear tensions between the U.S. and Russia have grown; the situation in North Korea has become more acute, with the country claiming to have tested a hydrogen bomb; tensions between Pakistan and India remain high (those countries are increasing their nuclear arsenals); and weapons-modernization programs in the U.S. and Russia continue to violate the spirit—and, I believe, the letter—of the Nuclear Non-Proliferation Treaty. The Paris agreement notwithstanding, the fight against climate change has barely begun, and it is unclear whether the nations of the world are ready to make the hard choices necessary to stabilize the climate and avert possible environmental disasters. In short, the major challenges the Bulletin laid out for governments a year ago have not been addressed, even as, over all, the global threats we face have become more urgent.

To understand the clock’s current position, it helps to look at recent history. In 2010, the clock was moved back, in part because President Barack Obama had pledged to try to move toward a world without nuclear weapons. His Administration did move forward on several diplomatic fronts, in regards to both arms-control treaties and negotiations with Iran. Since then, however, the U.S. has committed to a nuclear-weapons-modernization program—a program that aims, in part, to update the production, storage, and mechanisms of America’s warheads**—**that could cost between a hundred billion and a trillion dollars. What message does this send to non-nuclear nations about our intentions? The U.S. military has also begun exploring the use of smaller, “useable” nuclear-tipped missiles capable of attacking underground bunkers. There is, however, no sane strategic use of nuclear weapons; we need to reduce our nuclear arsenal, not create a new generation of armaments.

To help the clock move back, the Bulletin calls on the citizens of the world to make demands on their leaders. Leaders must dramatically reduce proposed spending on nuclear-weapons-modernization programs. They must reënergize the disarmament process, with a focus on results. They must engage with North Korea to reduce nuclear risks. They must begin to deal with the problem of commercial nuclear waste**,** in particular by agreeing on workable international storage sites**.** On climate change, they must follow up on the Paris accord with actions that sharply reduce greenhouse-gas emissions and fulfill the Paris promise of keeping warming at less than two degrees Celsius. And, more generally, they must create institutions specifically designed to explore and address potentially catastrophic misuse of new technologies.

The challenges facing humanity became truly global shortly after the end of the Second World War, when full-scale nuclear conflict became a real possibility. Climate change has only exacerbated that situation. Twentieth-century, business-as-usual approaches will not help us deal with these global challenges. As Albert Einstein said, after the first nuclear weapon was used in war, “Everything has changed, save the way we think.” Unless we change the way we think, humanity remains in serious danger. We should not be cowed into inaction by the daunting nature of the challenges we face. Instead, we have to face them head on.