Torchwood had been conducting experiments on the breach, in an attempt to harness its energy and reduce Britain's reliance on Middle Eastern oil, but these experiments had caused the breach to widen. The "ghosts" turned out to be Cybermen from an alternate universe, which were using the widening breach to travel between universes.
Torchwood experimented on the breach with hopes of obtaining its energy and diminishing Britain's dependence on Middle Eastern oil, but this led to the breach growing larger. The "ghosts," identified as Cybermen from a different universe, were utilizing the widening breach for inter-universal travel.