Editor’s note: Founded in 1945 by University of Chicago scientists who had helped develop the first atomic weapons in the Manhattan Project, the Bulletin of the Atomic Scientists subsequently created the Doomsday Clock in 1947 using the imagery of apocalypse (midnight) and the contemporary idiom of nuclear explosion (countdown to zero), to convey threats to humanity and the planet.

Editor's note: Founded in 1945 by University of Chicago scientists who had helped develop the first atomic weapons in the Manhattan Project, the Bulletin of the Atomic Scientists subsequently created the Doomsday Clock in 1947 using the imagery of apocalypse (midnight) and the contemporary idiom of nuclear explosion (countdown to zero), to convey threats to humanity and the planet. The decision to move the minute hand of the Doomsday Clock is made every year by the Bulletin's Science and Security Board in consultation with its Board of Sponsors, which includes 18 Nobel Laureates. The Clock has become a universally recognized indicator of the world's vulnerability to catastrophe from nuclear weapons, climate change, and new technologies emerging in other domains.

January 14, 2013

Dear President Obama,

2012 was a year in which the problems of the world pressed forward, but too many of its citizens stood back. In the US elections the focus was "the economy, stupid," with barely a word about the severe long-term trends that threaten the population's well-being to a far greater extent: climate change, the continuing menace of nuclear oblivion, and the vulnerabilities of the world's energy sources. 2012 was the hottest year on record in the contiguous United States, marked by devastating drought and brutal storms. These extreme events are exactly what climate models predict for an atmosphere overburdened with greenhouse gases. 2012 was a year of unrealized opportunity to reduce nuclear stockpiles, to lower the immediacy of destruction from missiles on alert, and to control the spread of fissile materials and keep nuclear terrorism at bay. 2012 was a year in which — one year after the partial meltdown at the Fukushima Daiichi Nuclear Power Station — the Japanese nation continued to be at the earliest stages of what will be a costly and long recovery.

The stasis of 2012 convinces us, the Science and Security Board, to keep the hands of the Doomsday Clock in place.

Mr. President, we see 2013 as a year for vision and engagement. We know that decisive action can make the world safer. Humanity awaits the US leadership that can secure a future free of nuclear weapons. US action can induce the world's nations to negotiate international agreements to avert the worst calamities of climate change. We turn to you, Mr. President, to lead us toward a safer world and to help us turn back the hands of the Doomsday Clock.

It remains five minutes to midnight.

Nuclear weapons. Mr. President, we applaud the steps your administration has already taken: ratifying the New Strategic Arms Reduction Treaty (New START), holding to firm account potential violators of the keystone Nuclear Non-Proliferation Treaty (NPT), strengthening the global nuclear security regime, and reducing the opportunities and chances of success for terrorists to get hold of fissile material. We are glad that your commitment to the Fissile Material Cut-off Treaty and the Comprehensive Nuclear Test Ban Treaty — for which we are confident you will seek Senate approval — has not wavered.

In 2009 you stood in Hradcany Square and boldly stated: "America's commitment to seek the peace and security of a world without nuclear weapons," and you specified that the United States will "reduce the role of nuclear weapons in our national security strategy, and urge others to do the same." Four years after the visionary speech, we see progress, but we also see how much remains to be done.

When the United States and Russia ratified New START, both countries agreed to limit the number of deployed warheads to 1,550. But 20 years after the end of the Cold War, this is not enough, and the United States must commit to cutting well below 1,000 warheads. The stockpile of non-deployed strategic nuclear warheads should be significantly reduced and tactical nuclear warheads must be eliminated. Mr. President, such actions will signal a decreasing role for nuclear weapons in US national security strategy — and they will demonstrate America's commitment to Article VI of the NPT to significantly reduce nuclear weapons and to strive for nuclear disarmament.

Mr. President, the 2010 Nuclear Posture Review considered eliminating a leg of the nuclear triad as part of the planned reductions under New START. We believe that, by cutting well below 1,000 warheads, the arguments for keeping all three legs of the triad are less convincing than they may have been in the past. The triad is an expensive legacy of a bygone era that makes it increasingly difficult to implement deeper cuts in the global nuclear arsenal. Now is the time to examine the options to fundamentally restructure US nuclear forces.

In addition, much more can be done to signal your commitment to reducing the role of nuclear weapons in national security strategy: You could increase the dismantlement rate of retired nuclear warheads, and consider seriously reducing both the 1,152 nuclear warheads on the submarine-launched ballistic missiles, as well as the 300 nuclear warheads assigned to bombers.

These measures would send a strong message of America's commitment to work toward a world without nuclear weapons.

As was the case in your first term, we hope that your second term will also begin with an updated statement articulating your future plans to reduce the role of nuclear weapons in US national security strategy.

Fissile materials. Within months of taking office in 2009, you announced the goal of securing all vulnerable nuclear material around the world within four years. This was a key public acknowledgment that all fissile material — whether separated for weapons purposes or civilian use — carries substantial proliferation risks. 2013 is the time to rejuvenate and expand the fissile-material agenda.

In 2010, you convened the first Nuclear Security Summit. However, these biennial meetings of heads of state have dealt primarily with securing and consolidating civilian stocks of highly enriched uranium (HEU) in non-nuclear weapon states, which account for less than 2 percent of the global stockpile of fissile material. Moreover, civilian HEU is not the only problem. To quote the speech you delivered last year at Hankuk University in South Korea: "We simply can't go on accumulating huge amounts of the very material, like separated plutonium, that we're trying to keep away from terrorists."

Mr. President, we call on you to launch, immediately, a comprehensive approach to fissile materials that deals with civilian and military stockpiles — plutonium, as well as highly enriched uranium. Independent estimates of the global stockpile suggest that there are 1,440 tons of HEU and 500 tons of separated plutonium. In principle, this is enough for several hundred thousand nuclear weapons.

Since the 1970s, the United States has refrained from reprocessing of civilian spent nuclear fuel and the separation of fissile materials. In 2013, the United States should discourage Japan from commissioning its Rokkasho plant and encourage South Korea to reconsider its reprocessing plans.

This year, the United States should declare excess all fissile material not in nuclear warheads — deployed or in reserve — and offer this material for international monitoring. 2013 is the year in which the United States should seek further reductions in its own fissile material stocks, as well as those held by Russia and other nuclear weapon states.

Mr. President, in 2013, the United States — in coordination with the other NPT nuclear weapon states, as well as India, Pakistan, Israel, and North Korea — should announce a moratorium on producing more fissile material for weapons, pending a formal treaty.

Climate change. Human activities are now the dominant cause of global climate change. Emissions of heat-trapping gases continued to climb in 2012, with atmospheric levels of carbon dioxide — the most important greenhouse gas affected by human activities — reaching levels higher than at any time in the past 800,000 years. 2012 was the hottest year on record for the contiguous United States. Arctic sea ice continued to rapidly diminish in extent, reaching a record low this past year that fell under the previous low by an area the size of Texas. Glaciers are retreating, and the massive Greenland and Antarctic ice sheets are losing mass. Extreme weather events, such as last year's Superstorm Sandy and Typhoon Bopha, now strike in an environment altered by climate change, with higher sea surface temperatures and more water vapor in the atmosphere to fuel and sustain their destructive power.

But 2012 also provided further evidence of the viability of renewable sources of energy and more efficient ways of powering the global economy, pointing toward an alternative to the high-carbon development model. Wind and solar power, for example, expanded at rates greatly exceeding what energy agencies forecasted earlier this decade. Owing to supportive policies, power generation from these sources expanded nearly fourfold over the past five years in the United States, and even more so in other countries, including Germany and China, where there they enjoyed stronger support. The new US automobile fuel economy standard was another welcome development, promising nearly a doubling of vehicle efficiency by 2025.

This trend, while encouraging, is by no means evidence that the climate challenge has been met. In fact, the growth in low-carbon energy sources is dwarfed by the continued expansion of fossil fuels like coal — as was exemplified last year by the explosive development of unconventional fossil resources, such as tar sands, oil shale, and shale gas. With life-cycle greenhouse gas emissions that are even worse than their conventional counterparts, these unconventional fossil resources threaten to crowd out investment in renewables and to entrench a long-term dependency on carbon-intensive energy supplies.

Avoiding this scenario will require your administration to considerably speed the process of reforming the patchwork of federal subsidies, taxes, and other incentives and disincentives that distort energy markets. We look forward to substantial progress toward rational energy markets in 2013, including the pricing of greenhouse gas emissions throughout the economy.

2012 saw the arrival of an apparently abundant domestic natural gas resource, which could be an important contributor to a more environmentally sound energy future. We call on your administration to see that commercialization of this resource is pursued in ways that mitigate its environmental impacts, including its climate change impacts. Specifically, we urge you to create strong regulations for gas developers to minimize methane leakage and safeguard water resources, and for power-plant developers to incorporate carbon dioxide capture and storage.

Mr. President, you have taken some steps to help nudge the country along a more rational energy path. You kept alive the incentives for wind and other renewable power, and you strengthened vehicle fuel-efficiency standards. These are important steps, but without a concerted effort to launch a comprehensive and ambitious response to the climate challenge in 2013, we face diminishing prospects for averting the worst and most costly effects of a disrupted climate.

Since your re-election, you have noted with concern that the Earth is warming and the Arctic ice cap is melting even faster than scientists had predicted, while extraordinary weather events — from storms to droughts — are taking their toll in the United States and around the world. You also stressed that we have an obligation to future generations to do something about climate change, and you promised that this would be a priority of your administration.

In September 2013, the Intergovernmental Panel on Climate Change (IPCC) will publish its fifth assessment of climate science, which will authoritatively document the changing climate. We call on you to commit your administration to firmly accept the panel's scientific findings, urgently integrate these findings into national policy, and confidently face those who irresponsibly argue that climate change science is not relevant.

Emerging threats. In 2012, Mr. President, it became clear that cyber technologies, for all their benefits, could trigger a new kind of self-inflicted Doomsday. But how, when, and for whom remains unclear.

Developments in 2012 underscored the vulnerabilities of government, international banking, finance, and industry to cyber attack. Saudi Aramco suffered the most damaging cyber attack on a company to date when three-quarters of its corporate computers were attacked by a virus that erased all data, replacing it with an image of a burning US flag. The malware used in the attack at Saudi Aramco has been linked to the same malware used in Stuxnet and related malware, Wiper and Flame. Such developments have advertised the destructive possibilities of hostile cyber operations, governments' plans to use them, and the blowback that can happen when they do.

The proliferation and commoditization of digital data has, in the words of one senior US government official, contributed to a "new threat matrix of digital espionage, crime and warfare" that puts personal security and liberties at risk.

What should we make of this new technological challenge? Is the evolution of cyber technology outpacing societies' capacities to manage it equitably — the same kind of socio-scientific gap that inspired scientists in the nuclear domain to press for international institution-building and arms-control initiatives so many decades ago? The Science and Security Board is studying a way forward on this issue, and hopes your administration, Mr. President, will continue to do so as well.

Next steps. Mr. President, with your second inauguration one week away, we have as much hope for your presidency as we did in 2010, when we moved back the hands of the Doomsday Clock after your first year in office. You have an extraordinary capacity to articulate the global desire for peace and security, and you have the tools to deliver tangible progress. Your Prague speech on nuclear disarmament and your efforts at Copenhagen to coordinate world leaders to slow the onset of climate change are high water marks in their respective basins of activity. We call on you to reinvigorate these initiatives. Specifically:

Implement your Prague vision to diminish the role of nuclear weapons in US security strategy by committing to cut — to under 1,000 — the deployed strategic nuclear warheads.

Announce an effort to stop all new production and eliminate existing stocks of separated fissile materials, both civilian and military, worldwide. It would greatly strengthen the nonproliferation regime, support nuclear disarmament, and provide the ultimate protection against nuclear terrorism.

Prioritize climate change at a level that recognizes the gravity of the climate threat. You have the ability to educate and inspire the United States to launch an ambitious response, confront entrenched interests that have forestalled action, and, if Congressional dysfunction prevents legislative action, you are able to use your executive powers to achieve progress on a rational energy and climate strategy for the nation.

Partner with other world leaders to forge the comprehensive global response that the climate threat demands, based on equity and cooperation across countries. A global solution will only be within reach if the United States commits to doing its fair share by investing at home and globally to curb greenhouse gas emissions, while building resilience in the face of the climate disruption that is now unavoidable.