|Fig. 1: Doomsday clock. (Source: Wikimedia Commons).|
Society has rapidly evolved in the past century. Gains in science and technology are increasingly exponential. Unfortunately, these gains also come with terrible side effects. In the last half century, we have advanced to the point where we have the technology to wipe out most of the life on our planet either slowly with pollutants or rapidly with nuclear weapons. If these two things are left unchecked, then we will be the cause of our own destruction. Just recently (January 15, 2015), the Bulletin of Atomic Scientists moved the "Doomsday" Clock to three minutes until "midnight". They claim that "unchecked climate change, global nuclear weapons modernizations, and outsized nuclear weapons arsenals" are a major threat to the existence of humanity.  While nuclear weapons will always be a threat, is this threat as large as they claim?
There are only five "official" nuclear weapons states in the world: China, Russia, France, United Kingdom, and United States.  Of those five, only Russia and the United States have a significant number of nuclear weapons.  This, of course, is a product of the Cold War arms race between the two nations. The five nuclear weapons states are bound by the Treaty on the Proliferation of Nuclear Weapons, or NPT. The NPT is probably the most significant and effective proliferation treaty in existence. It was ratified in 1970 and also includes 185 non- nuclear weapons states. The treaty's goal is to prevent the spread of nuclear weapons and promote cooperation between nations on the issues of nuclear energy and nuclear disarmament.  The treaty divides nations into two categories: Nuclear States and Non-Nuclear States. Non- nuclear states that have ratified the treaty are prohibited from acquiring nuclear weapons. However, they are free to research and develop nuclear energy technology and to benefit from peaceful nuclear explosions.  There are three nations that possess nuclear weapons and have not ratified the NPT: India, Israel, and Pakistan.  However, their arsenals are small and they currently do not represent much of a threat politically. There are also two nations that are of immediate proliferation concern: North Korea and Iran. 
Nuclear disarmament is a complex subject that is rife with politics. There have been many unilateral, bilateral (United States and Russia), and multilateral efforts to reduce the arsenals of the nuclear weapons states. In total, worldwide arsenals have been reduced by about 77% from a peak total of 70,000 during the Cold war to 16,400 as of 2014.  Unilateral efforts are probably the easiest way to reduce arsenals, however nuclear nations tend to want to keep some as a deterrent. There have been four major treaties between the United States and Russia for nuclear arms reduction. The latest of which is the New Start treaty signed in 2010. However, United States and Russian relations have grown cold over the situation in Ukraine. This will likely stall any efforts for bilateral nuclear disarmament in the near future. Multilateral efforts are the most difficult to implement. The only major multilateral disarmament treaty is the Comprehensive Nuclear Test-Ban Treaty.  While it does not actually reduce the number of nuclear weapons, it does place a ban on all nuclear testing. This would at least prevent nations from growing their arsenals and it would be a first step toward complete disarmament. Unfortunately, it has not yet been ratified since it was first open for signature in 1996.  Complete disarmament will probably take many years and much cooperation between world governments. More effort should be invested in making nuclear disarmament an issue during national elections.
In the debate over nuclear disarmament, there is an idea called mutual assured destruction (MAD). The idea is that if the potential participants in a nuclear war (such as Russia and the United States) have a large enough stockpile of nuclear weapons, an actual nuclear war would bring about the total annihilation of those participants.  This has the effect of deterring a nuclear war from taking place. If one side decided to attack, it would essentially be suicide. This peak of this idea came about during the Cold War in the nuclear arms race between the Soviet Union and the United States. MAD was probably one of the reasons the Cold War did not escalate into an actual war. The problem with any offensive deterrent is that it's a tense and very unstable equilibrium. Everything is fine as long as the deterrent is working but if something goes wrong, it avalanches into a crisis of unprecedented magnitude. A simple accident such as a malfunctioning computer could start a nuclear apocalypse. Such an event actually almost happened during the Cold War.  A much better and more peaceful deterrent to war would be defensive measures such as missile defense systems rather than offensive measures. Another huge problem with MAD is that an increase of availability of nuclear weapons and fissile material would make it easier for terrorists to obtain them.
The use of nuclear weapons by terrorists is the biggest nuclear threat we face today. Terrorist groups have expressed interest in nuclear weapons but do not yet have the capability to use one. There are three ways terrorists can attain a nuclear weapon. They can steal it from the arsenal of a nuclear nation, buy it from a rogue nuclear nation such as Iran or North Korea, or they can build an improvised nuclear device.  Probably the easiest way would be for them to steal fissile material from a nuclear weapons stockpile or nuclear reactor and use it to construct a custom bomb. It would take just twenty-five kilograms of highly enriched uranium or eight kilograms of plutonium to construct a crude nuclear weapon.  There are ongoing efforts such as the Cooperative Threat Reduction and the Global Threat Reduction Initiative to secure and eliminate fissile material. However, there is still too much "loose" material around the world. Starting in 2010, a nuclear security summit will be held every two years to discuss the issue.  Given the grave nature of nuclear terrorism, there needs to be much more funding and international cooperation to provide the infrastructure and regulations needed to ensure that terrorists do not have easy access to fissile material.
North Korea is the biggest state-sponsored nuclear threat. Negotiations with North Korea have been ongoing since they threatened to pull out of the NPT in 1994. Progress was being made until North Korea formally withdrew from the NPT in 2003. However another round of negotiations began which saw North Korea almost return to the NPT. Negotiations came to a halt in 2009 after an internationally condemned North Korean rocket launch.  Since then, North Korea has made many threats to use nuclear weapons against South Korea and the United States. So far, they have tested three nuclear weapons.  In 2013, it was revealed that North Korea has the capability to mount a nuclear warhead on a missile. However, it would be unreliable and would probably not have the range to reach the United States mainland.  As of right now, North Korea's threats are mostly propaganda and rhetoric. However, it is foreseeable that they will have the technology to actually carry out a coordinated attack within a few years based on their current development. Whether or not they would actually use that technology depends on political dynamics. It seems North Korea is using their threats as a means to get what they want politically. For example, they just rejected another round of talks because of military exercises performed by South Korea and the United States.  Both sides are in a political stalemate where neither side will budge on the issues being discussed. If one side is willing to compromise, then negotiations can start back up again in which case North Korea will cease to be a threat. According to Daryl Kimball, the best strategy for diverting a catastrophe is to keep denuclearization from being a precondition for negotiations and to negotiate with North Korean allies such as China. Sanctions may also help in decreasing North Korea's ability to develop weapons. Overall, the probability of an attack is very low because it would be "suicide" for North Korea. 
Iran is another nation that is of concern for nuclear proliferation. In 1967, the United States provided Iran with a nuclear reactor which used weapons grade uranium. In 2002, it was revealed that Iran has a nuclear weapons program. Since then, negotiations to end the program have gone through various stages of progress and setbacks.  Iran has been adamant that it is only developing peaceful nuclear technology however the world powers have evidence to the contrary. Iran has not made any threats to carry out a nuclear attack but because of powerful terrorist groups in the area, their nuclear program is still a big concern.
When people think of nuclear bombs, they usually think of war, destruction, and weapons. However, nuclear bomb technology can also be used for peaceful purposes. In fact, the United States and Russia have already experimented with peaceful nuclear explosions although not much has been gained from them. Potential applications include the creation of reservoirs and canals, mining, oil and gas recovery, energy production, space propulsion, and averting a collision with an asteroid.  In order to continue research and development into peaceful nuclear explosions, we must not fully deplete our arsenals although we can de-weaponize our warheads. However, this still leaves the possibility of re-weaponizing those nuclear bombs. This is one of the issues in the debate on whether full disarmament is the right thing to do. Two deciding factors are whether the gains from peaceful nuclear explosions are worth the risk of weaponization and also the current state of nuclear threats and proliferation. Probably the most important application is averting a collision with an asteroid or other near Earth object (NEO). A rocket would be fitted with a nuclear warhead and launched into space where it will deliver the warhead to the NEO. The force of the nuclear explosion will knock the NEO off course thereby averting a collision. Now this is not the best way to avoid a collision as it can knock the NEO into a return orbit or simply smash it into pieces without actually avoiding the collision. There are better ideas such as smashing a spacecraft into the NEO or using a gravity tractor.  However, we do not currently have the finances or the infrastructure to actually carry out these alternative plans in the case of an emergency.  Despite the very low probability of being hit, we must still be prepared in the event of an unidentified object or a change in trajectory of a known object. Thus, nuclear warheads may be our best option for collision avoidance until we develop alternate methods.
Nuclear attack is probably the greatest immediate threat to mankind today. While the Bulletin of Atomic Scientists' conclusion may be a bit premature, if we don't concentrate our efforts on nuclear security and disarmament then doomsday may indeed only be "minutes" away. The most immediate concern is nuclear security. We must make nuclear material next to impossible for terrorists to obtain. The next concern is disarmament. The probability of us destroying ourselves with our nuclear arsenal is probably greater than any benefit that nuclear bombs can provide. Thus we should focus on complete disarmament by all nuclear nations. Missile defense systems can be built as a defense in the event that a rogue nation obtains a nuclear weapon.
© Mario Chapa. The author grants permission to copy, distribute and display this work in unaltered form, with attribution to the author, for noncommercial purposes only. All other rights, including commercial rights, are reserved to the author.
 T. Leopold, ""Doomsday Clock Moved Closer to Midnight," CNN, 23 Jan 15.
 "Treaty on the Non-Proliferation of Nuclear Weapons," U.S. Department of State, U.S. Department of State, 2010.
 "Worldwide Nuclear Arsenals, Union of Concerned Scientists, April 2010.
 "World Nuclear Forces," in SIPRI Yearbook 2013, Stockholm International Peace Research Institute (Oxford U. Press, 2013).
 J. E. Medalia, "Comprehensive Nuclear-Test-Ban Treaty: Background and Current Developments," Congressional Research Service, RL33548, September 2014.
 M. Shermer, "Will Mutual Assured Destruction Continue to Deter Nuclear War?" Scientific American, 1 Jun 14.
 "Nuclear Terrorism Fact Sheet," Belfer Center, Harvard University, April 2012.
 K. Brill and K. Luongo, "Nuclear Terrorism: A Clear Danger," New York Times, 15 Mar 12.
 J. Ryall, "North Korea Nuclear Tests: Timeline." The Telegraph, 12 Feb 13.
 L. Martnez, "North Korea Can Put A Nuke on a Missile, U.S. Intelligence Agency Believes," ABC News, 11 Apr 13.
 M. Hunter, "North Korea Warns US of 'Disastrous Final Doom'," ABC News, 4 Feb 15.
 R. York, "Will North Korea Ever Use Its Nuclear Weapons?," The Guardian, 31 Oct 14.
 "Timeline of Iran's Nuclear Programme," The Guardian, 24 Nov 13.
 S. Kaufman, Project Plowshare: The Peaceful Use of Nuclear Explosives in Cold War America (Cornell U. Press, 2012).
 T. Graham, Jr., and R. L. Schweickart, "NASA's Flimsy Argument for Nuclear Weapons" Scientific American, 8 Feb 08.
 S. Ferro, "America's Best Current Defense Against Asteroids Is ... Prayer?" Popular Science, 20 Mar 13.