Timescape — Gregory Benford

1998. Earth is falling apart, on the brink of ecological disaster. But in England a tachyon scientist is attempting to contact the past, to somehow warn them of the misery and death their actions and experiments have visited upon a ravaged planet.

1962. JFK is still president, rock 'n' roll is king, and the Vietnam War hardly merits front-page news. A young assistant researcher at a California university, Gordon Bernstein, notices strange patterns of interference in a lab experiment. Against all odds, facing ridicule and opposition, Bernstein begins to uncover the incredible truth ... a truth that will change his life and alter history ...the truth behind time itself.