A time to hate - Robert Greenberger

The long-running blood feud between two alien peoples came to a sudden close a century ago when both races colonised the planet Sigma IV. But their unaccustomed harmony turns out to be caused by a natural gas released by their new home planet -- an effect that scientists now determine will kill them over time. A treatment intended to nullify the long-term damage and danger has catastrophic results, triggering worldwide carnage as long suppressed aggression and rage are suddenly released.
In the midst of this maelstrom of hatred and violence is the USS Enterprise-E, on a mission which is going from bad to worse. Captain Jean-Luc Picard -- a man still waging his own personal battle for redemption in the eyes of his commanding officers -- must somehow find a way to resolve the disaster and save the lives of his crew.