I don't think that global warming is going to be a major consequence of this spill for a couple of reasons;

1. Very little, if any, methane gas is actually being released into the atmosphere. The vast majority is staying in solution.

2. The NASA study in post #6 is talking about vast amounts of methane being released over many years possibly by the collision between India and Asia, dwarfing our current tragedy.

See also this thread;