Complex sentence: Massive clouds of CO 2 such as those released from lakes in Cameroon in the 1980s can cause widespread devastation of human and wildlife populations, however may have little or no effect on local vegetation.
Split into simpler sentences: Massive clouds of CO 2, such as those released from lakes in Cameroon in the 1980s, can cause widespread devastation of human and wildlife populations. However, they may have little or no effect on local vegetation.