The supercommittee's failure to reach an agreement on debt reduction will probably result in unexpected reductions of the U.S. nuclear arsenal. That possibility concerns the defense establishment, but it also presents an opportunity: It might finally be possible to have an honest debate about the role of nuclear weapons in U.S. strategy and the prospect for further arms reductions.

Before moving ahead with this conversation, though, it is critical to review and debunk three misguided ideas about nuclear weapons.

The first is that our nuclear world is safe and stable and that all we need to do now is prevent other nations from acquiring nuclear weapons. Though it is undoubtedly true that the U.S. stockpile is safer than ever, the dangers are far from over. Nuclear terrorism remains a threat. Mistakes are possible, too. In just one example, in August 2007, six nuclear warheads disappeared for two days between North Dakota's Minot and Louisiana's Barksdale Air Force bases.

What's more, unsafe nuclear weapons elsewhere remain a major threat. Tensions between nuclear India and Pakistan, the security of the Pakistani nuclear arsenal and the future of the North Korean nuclear weapons program all suggest that the commitment to making U.S. weapons more reliable and secure will not solve the problem.

The second piece of nuclear mythology is that nuclear disarmament has never taken place and never will. Put slightly differently, it is the idea that nuclear history is proliferation history. But nuclear disarmament is far from unprecedented. South Africa, Ukraine, Belarus and Kazakhstan all disarmed. Many nuclear-capable states chose to pursue security without nuclear weapons because policymakers recognized these weapons would endanger rather than protect them. Sweden went down the nuclear path and then decided against it in the late 1960s.

Germany had a nuclear weapons program during World War II but became a law-abiding, non-nuclear member of the Non-Proliferation Treaty. Japan had two nuclear weapons programs during the war and accumulated a significant quantity of plutonium; since then, its authorities thought about restarting a weapons program four times but decided against it.

In each of those cases, most analysts did not believe that giving up nuclear weapons ambitions was possible. They were wrong, and today we all are glad these countries chose the path they did.

The third misguided concept is that reducing the size of the U.S. nuclear arsenal will lead to proliferation. Those who believe this think that countries that no longer feel protected by U.S. nuclear weapons will start building their own to protect themselves. Although this might have some validity, it should be assessed on a case-by-case basis.

Historically, many of the states that have disarmed or given up their nuclear-weapon ambitions - including every non-nuclear nation outside of NATO - have done so despite the absence of a nuclear-security guarantee.

On the other hand, states determined to get the bomb, such as the United Kingdom and France, have done so despite security guarantees. Finally, this argument assumes that the role of nuclear weapons in future alliances and geopolitical relationships will be as important as it was in the past. This might be true, but it cannot be considered a fact. It is just a bet on the future and a set of policy priorities.

In 2007, "the four horsemen" - Henry Kissinger, Sam Nunn, William Perry and George Shultz - wrote a highly influential opinion piece in the Wall Street Journal arguing that relying on nuclear weapons for the purpose of deterrence has become "increasingly hazardous and decreasingly effective." Coming from former Cold Warriors from both sides of the political aisle, it legitimized the goal of a world without nuclear weapons and challenged the conventional wisdom.

Now policymakers in Washington and candidates on the electoral trail should embrace the issue, and begin a real conversation with the electorate about the role of nuclear weapons in U.S. policy rather than allowing that policy to be driven by inertia or budget cuts.

Reducing carbon-dioxide emissions is primarily a political problem, rather than a technological one. This fact was well illustrated by the fate of the 2009 climate bill that barely passed the U.S. House of Representatives and never came up for a vote in the Senate. The House bill was already quite weak, containing many exceptions for agriculture and other industries, subsidies for nuclear power and increasingly long deadlines for action. In the Senate, both Republicans and Democrats from coal-dependent states sealed its fate. Getting past these senators is the key to achieving a major reduction in our emissions.

Technological challenges to reducing emissions exist, too. Most pressing is the need to develop the know-how to capture carbon dioxide on a large scale and store it underground. Such technology could reduce by 90 percent the emissions from coal- fired power stations. Some 500 of these facilities in the U.S. produce 36 percent of our CO2 emissions.

But these plants aren’t evenly spaced around the country. And therein may lie the key to addressing the political and technological challenges at the same time. If the federal government would invest in carbon capture and storage, it could go a long way toward persuading politicians in every state to sign on to emission reductions.

I’ll get to the specifics of the technology shortly. But first, consider how the costs of emission reduction fall hardest on certain parts of the country: A carbon tax levied on all major sources of released CO2, the approach favored by most of the environmental community, would make energy from coal-fired power plants cost more. To make a significant difference, such a tax would have to amount to $60 a ton.

Midwest Carbon Footprint

As a result, gasoline prices would rise 26 percent, and natural gas for household usage by 25 percent, nationwide. Rich and urbanized states could probably tolerate this. The West Coast, with its hydroelectric power, and the Northeast, which relies to a large extent on natural gas, could most easily absorb the associated increase in energy costs.

But the price of energy in the rural, Midwestern states would more than quadruple because of their large carbon footprint. Midwesterners get most of their electricity from coal; they drive relatively long distances to get to work, shopping and entertainment; and rural homes and buildings use more energy for heating and cooling.

One carbon-tax proposal now being considered is a “cap and dividend” plan that would send the tax revenue back to all U.S. citizens equally. But that would also favor the rich states that are less dependent on driving and coal.

It would be more helpful for the coal-dependent states if the federal government would use revenue from a carbon tax to help develop the technology for carbon capture and storage.

And that brings us to the technological challenges: No plant of any size with the capacity for CCS yet exists, but it has been demonstrated to work at small scales. Three different processes for capturing the CO2 are being tested, and scaling them up for 500-megawatt or 1,000-megawatt facilities should be possible.

For two years, the Mountaineer plant in New Haven, West Virginia, has been capturing and storing a tiny amount of its CO2 -- 2 percent of it -- but plans to build a full-scale carbon-capture plant here have been abandoned. Because Congress has dropped any idea of imposing a tax on carbon emissions, the investment doesn’t make sense.

A large plant in Edwardsport, Indiana, was being constructed with the expensive gasification process that makes it easy to add carbon-capture facilities, but it, too, has been shelved.

China may finish its large demonstration carbon-capture plant before the U.S. gets any model up to scale. Others are planned in Europe, and a small one is operating in Germany. This plant has been unable to get permission for underground storage, so it is selling some of its CO2 to soft-drink companies and venting the rest.

Subterranean Storage

Storing captured CO2 is eminently possible, too. For 15 years, the Sleipner facility in Norway has been storing 3 percent of that country’s CO2 underneath the ocean floor, with no appreciable leakage. Algeria has a similar facility, the In Salah plant, operating in the desert.

One storage strategy under consideration in the U.S. is to inject captured CO2 into huge basalt formations off both the east and west coasts. Inside the basalt, the carbon gas would gradually turn into bicarbonate of soda.

There are other ways to dispose of carbon dioxide. It has been used for enhanced oil recovery for many decades without any danger, and has been effectively stored in depleted oil reservoirs. (The gas is dangerous only in high concentration.)

It remains uncertain how much of the captured CO2 might leak during storage. Even if this were as much as 10 percent, however, it would mean that 90 percent of it would stay underground.

As CCS technology develops, it will have to be made more efficient so that it uses less energy. As it is, the capture phase is expected to require that a power plant burn 20 percent to 25 percent more coal than it otherwise would.

The technological challenges may explain why energy companies haven’t lobbied for subsidies to develop CCS. The electric-energy sector isn’t known for innovation and risk- taking. Just look at the U.S.’s outdated power grid.

But the federal government could pay for the subsidies through a tax on carbon. Such a levy would have other advantages, too: It would raise the cost of energy to reflect the damage that burning coal and oil now do to the environment, and spur the development of renewable sources.

If states with large carbon footprints can’t accept such a tax, the CCS subsidies could be paid from the general fund. The cost to build coal-fired power plants with CCS technology is estimated to be about $5 billion to $6 billion -- about the price of a single nuclear power plant. The total price for the U.S.’s 500 large plants would be $250 billion. That’s as much as the planned modernization and expansion of our missile defense system over 10 years.

But it would slash our carbon emissions by at least 20 percent. There is no other politically possible way to cut CO2 as much, and as quickly -- in a decade or two. And devastating climate change is far more likely than a missile attack.

U.S. investment in CCS technology could also induce China and Europe to follow suit. And this would allow the world time for renewable-energy technologies to mature -- to the point where we could do away with coal burning altogether.