One source of global warming
I believe the answer is:
coal
(Other definitions for coal that I've seen before include "Char" , "Carbonized vegetable matter" , "Carbonaceous rock used as fuel" , "slack" , "Fossil fuel" .)
I believe the answer is:
coal
(Other definitions for coal that I've seen before include "Char" , "Carbonized vegetable matter" , "Carbonaceous rock used as fuel" , "slack" , "Fossil fuel" .)