Future's Dark Past - J L Yarrow - Bog

The catastrophic Purge War at the end of the twenty-first century destroys planet Earth, jeopardizing the future for the remnants of humanity. Horrific repercussions roll across the ages until, generations later, a scientific group called the Time Forward Project harnesses a deep-space wormhole in which they can travel through time. They find the portal unstable and shrinking, but they have little choice but to take desperate, drastic measures and journey back to prevent the war.