If the definition of insanity is doing the same thing over and over and expecting a different result, the definition of obstruction is knowing exactly how to fix a problem and pursuing everything but the obvious solution. The U.N. Environment Program’s attempts to negotiate a global plastic treaty is suffering from both of these afflictions at once.Negotiators are gathered in Nairobi this week for the third of five meetings to broker a treaty to reduce plastic pollution. The past two meetings di