scientists believe that the earth's climate may be warming up. (2) This trend probably began thousands of years ago. (3) Many areas of the earth used to covered with ice that has now melted. (4) However, in recent years, the warming trend speeded up. (5) Scientists think that part of the reason for this may be has dioxide pollution from industry and automobiles. (6) The carbon dioxide mixes with other gases. This pollution covers the earth like a blanket keeps it warmer. (8) Another reason for the warming may be the fact that the earth is losing its forests. (9) Forests are an important part of the earth's system using up carbon dioxide and keeping the air temperature cool.