Greenhouse emissions: Iceland volcano v. European airliners

Ever since that volcano started farting ash at an obnoxious rate last week, I wondered to my self: Self, are the greenhouse gases emitted by that volcano offset by the jets that have been grounded all over Europe?

I was able to find this diagram.  Though its creator was well-meaning, there are just too many factors to take into account and process.  Read the comments section for the variables.