you have a better chance of being killed by and orbital bombardment of feathers than the LHC causing ANY global problems. the LHC can propel particles near C velocities. on top of that these particles can carry a potential energy of 7 tera electron volts. i know, hard to really comprehend, but just think STUPID FAST AND STUPID STRONG. with all that being said, the stranglets pose earth no threat. the planet is actually being bombarded by far higher energies every day all the time. we just have a hard time getting a detector sensitive enough (and small enough) into orbit to see these events.
if you want a real simple explenation of all this, listen to the podcast "Skeptoid #109: Will the Large Hadron Collider Destroy the Earth?". the link to the episode, transcript of the episode, references, and discussions can all be found here
"will the large hardron collider destroy the earth?"