The problem here is one of complexity and durability. First you have to decide who the participants in this limited nuclear war would be. For an easy suggestion let's say the U.S. vs Iran and North Korea. Then the rules: Beginning tomorrow, both sides have 2 weeks to deliver some predetermined number of weapons to the other side and set them off. After 2 weeks, the winning side would get to deliver the losers shortfall to their targets of choice. As to durability, it is suggested that this solution might not last more than 10 years, necessitating another go-round.
I have a better and much cleaner idea: Let's let the EPA call a global conference on Global Warming with scheduled speeches by John Kerry, Michael Mann and Al Gore, to be held on Earth Day at EPA headquarters in D.C. Invite everybody; Earth first!, Greenpeace, PETA, the lot. Big draw would be a lottery for a billion dollar grant to be awarded to the winner of a drawing to be held at noon. Must be present to win. When the card is pulled and the name is announced, we detonate the modest sized nuke in the building basement. Voila! We never have to hear about global warming again. Collaterally I could think of several other problems this would solve as well.
Well I like the idea.