Rivers in time2000

"Several times in the distant past, catastrophic extinctions have swept the Earth, causing more than half of all species - from single-celled organisms to awe-inspiring behemoths - to suddenly vanish and be replaced by new life forms. Today the rich diversity of life on the Earth is again in grave danger - and the cause is not a sudden cataclysmic event but rather humankind's devastation of the environment. Is life on our planet teetering on the brink of another mass extinction? In this new book, acclaimed paleontologist Peter D. Ward answers this daunting question with a resounding yes"--Book jkt.