The Cusanus Game, Jeschke Wolfgang

Biologist Domenica Ligrina fears her planet is dying. She might be right.

An atomic disaster near the French-German border has contaminated Northern Europe with radioactivity. Economic and political calamities are destroying the whole planet. Human DNA is mutating, plant species are going extinct, and scientists are feverishly working on possible solutions. It becomes increasingly apparent that the key to future salvation lies in the past. In 2052 a secret research facility in the Vatican is recruiting scientists for a mission to restore the flora of the irradiated territories. The institute claims to have time travel. When Domenicas sometime-lover tells her that he knows her future but that she must decide her own fate, she enlists despite his ambiguous warning.

The Middle Ages hold Domenica spellbound. She immerses herself in the mysteries, puzzles, and peculiarities of a culture foreign to her, though she risks changing the past with effects far more disastrous than radiation poisoning. Perhaps there is more than one Domenica, and more than one catastrophe
In the tradition of Stanislaw Lem and Philip K. Dick, Wolfgang Jeschkes The Cusanus Game is a novel of future disaster in Europe by the grand master of German science fiction