03/07/2014 10:16 am ET | Updated May 07, 2014

Best And Worst Case Scenarios for Ukraine Crisis: World Peace And Nuclear War

No one yet knows how the Ukraine crisis will play out. Indeed, the whole story is a lesson in the perils of prediction. Already we have a classic: "Putin's Bluff? U.S. Spies Say Russia Won't Invade Ukraine," published February 27, just as Russian troops were entering Crimea. But considering the best and worst cases highlights some important opportunities to make the most of the situation.

Here's the short version: The best case scenario has the Ukraine crisis being resolved diplomatically through increased Russia-Europe cooperation, which would be a big step towards world peace. The worst case scenario has the crisis escalating into nuclear war between the United States and Russia, causing human extinction.

Let's start with the worst case scenario, nuclear war involving the American and Russian arsenals. How bad would that be? Put it this way: Recent analysis finds that a "limited" India-Pakistan nuclear war could kill two billion people via agricultural declines from nuclear winter. This "limited" war involves just 100 nuclear weapons. The U.S. and Russia combine to possess about 16,700 nuclear weapons. Humanity may not survive the aftermath of a U.S.-Russia nuclear war.

It seems rather unlikely that the U.S. and Russia would end up in nuclear war over Ukraine. Sure, they have opposing positions, but neither side has anywhere near enough at stake to justify such extraordinary measures. Instead, it seems a lot more likely that the whole crisis will get resolved with a minimum of deaths. However, the story has already taken some surprising plot twists. We cannot rule out the possibility of it ending in direct nuclear war.

A nuclear war could also occur inadvertently, i.e. when a false alarm is misinterpreted as real, and nuclear weapons are launched in what is believed to be a counterattack. There have been several alarmingly close calls of inadvertent U.S.-Russia nuclear war over the years. Perhaps the most relevant is the 1995 Norwegian rocket incident. A rocket carrying scientific equipment was launched off northern Norway. Russia detected the rocket on its radar and interpreted it as a nuclear attack. Its own nuclear forces were put on alert and Boris Yeltsin was presented the question of whether to launch Russia's nuclear weapons in response. Fortunately, Yeltsin and the Russian General Staff apparently sensed it was a false alarm and declined to launch. Still, the disturbing lesson from this incident is that nuclear war could begin even during periods of calm.

With the Ukraine crisis, the situation today is not calm. It is even more tense than last year, when the United States was considering military intervention in Syria. By coincidence, Israel had a pre-scheduled ballistic missile defense test during that brief period. Despite the tensions, Israel conducted its test, launching two missiles from the Mediterranean towards Israel. Russian radar again picked up the launch, initially suspecting it was the start of military action before Israel set the record straight. This incident could have escalated, especially because the U.S. and Russia had opposing positions on Syria. Fortunately, the confusion was quickly resolved and no escalation occurred.

Russia and the U.S. can reduce the risk of inadvertent nuclear war by keeping their nuclear detection and launch forces at normal or day-to-day levels of alert. This means that the forces will be less likely to falsely interpret any detected signal as an attack, and less likely to mistakenly launch an attack in response to a false alarm. Using a normal posture instead of a heightened nuclear alert level gives both sides more time to correctly interpret what signals they detect. This could help prevent an inadvertent nuclear war. Meanwhile, all parties involved can also take reasonable steps to reduce tension levels. This can be achieved by emphasizing diplomatic solutions instead of military interventions, and by preventing any military activities from escalating beyond Ukraine. Everyone should hope that such steps are taken.

And now for the best case scenario. There is compelling reason to believe that the Ukraine crisis could end with the world being much safer and at peace than it was before the crisis, if certain steps are taken. Perhaps these steps could have been taken without the crisis. But the crisis has done an excellent job at focusing global attention on Ukraine and its challenges. Let no crisis go to waste.

Ukraine's crisis is ultimately driven by its status as a geopolitical anomaly. Ukraine does not fit neatly within established geopolitical divisions. It is a border country, straddling the European Union bloc and the Russian bloc. Likewise, the country's population is split approximately in half by people who want to integrate with Europe and people who want to integrate with Russia. The recently deposed President Viktor Yanukovych is among those in Ukraine who have indicated interest in both the EU and the Russian-led Customs Union. But the EU and CU would not accommodate dual status, and now Yanukovych is in exile and the country in chaos.

It is unfair that Ukraine is in this unfortunate geopolitical predicament and must suffer the resulting political crisis. But perhaps in crisis there can be opportunity. Perhaps now the EU and CU can work towards a special dual status for Ukraine. If Europe and Russia are both serious about a peaceful resolution to the crisis that respects Ukraine's democratic wishes and territorial sovereignty, dual status may be the best option. Dual status would meanwhile help bring Europe and Russia closer together in peace and economic cooperation. We have today a great opportunity to put the Cold War further into the past.

Supposing a cooperative arrangement for Ukraine is feasible, one might ask, Who loses? The obvious answer is China, which could feel threatened by a unified NATO-Russian bloc. Other countries may feel similarly. To reduce this downside, EU-Russian dialog should seek input from China and any other interested countries. Such dialog is consistent with broader efforts towards the mutual security and understanding that some posit as important to achieving peace in a world without any nuclear weapons. And so a cooperative Ukrainian arrangement can work at the global scale too. For the sake of us all, this option should be pursued now.

So which will it be: best case, worst case, or somewhere in between? Much depends on Russia's motives, in particular whether it is seeking to keep the peace, as it claims, or if it has an aggressive, expansionist objective. Hopefully it is the former, in which case there is a good chance of reaching a diplomatic agreement without people dying. And I think that the former is more likely. But until the world knows for sure, it should remain vigilant. There is simply too much at stake.