# 9 The global warming

I think global warming is a serious threat to our enviroment because it is the dangerous signal from the nature. First, it is caused by gas of car. It means there are too many cars and they release gas. It is not good for nature and of course also not good for human. It is the one of the reason of an allergy. Second, it means the system of greens doesn't work well. Trees usually release O2 and absorb CO2, but now there are too much CO2 becaouse we cut the trees a lot. distruction of the nature system causes more seriouce troubles. Third, it makes ice of the South pole melt. The sea level of each seashore will be 9cm higher and cover many small islands. Millions of people who are living in islands will not be able to servive. We should think about the signal of the global warming.