มื่อมีแก๊สคาร์บอนไดออกไซด์ในอากาศจำนวนมากทำให้เกิดภาวะโลกร้อน
The first problem is environmental problem. The environmental problems is the most obvious problems in the present. Due to used fossil energy such as oil, etc. caused the many carbon dioxide in the air. The deforestation makes trees have decreased and absorb carbon dioxide are less.