Translate the following sentence into English.
各国的科学家意识到威胁人类生存环境的那些严峻的事实，向人类发出严重的警告。
【正确答案】：
AWARE OF THE HARSH FACTS CONCERNING THE DANGERS TO THE ENVIRONMENT, SCIENTISTS IN VARIOUS COUNTRIES HAVE SOUNDED A SERIOUS WARNING TO MANKIND.
【题目解析】：
考点：意识到be aware of；严峻的事实harsh facts；发出严重的警告sound a serious warning；人类mankind。