The recent Global Biodiversity Assessment of the United Nations Environment Program (UNEP) has identified four major causes of the present decrease in biodiversity,and a fifth,which may yet prove to be important.

• 联合国环境规划署近来对全球生物多样性进行了评估，已经确定目前生物多样性下降的四个主要原因，并且可能还证明了第五个方面也是重要的。