Scientists even predict that by the middle of the next century, a quarter of the species now living on our planet will be close to extinction, or already extinct. The loss this will bring to mankind is incalculable, and will clearly threaten man's own survival.
科學家甚至預測，下一個世紀中葉來臨之前，現有地球上的生物將有四分之一面臨絕種或消失，人類遭受的損失難以估計，明顯的危及本身的生存。