In this research we try to explain the greenhouse effect by suggesting a model looking to the earth –atmosphere system as a thermal machine .In this model earth absorbed heat and light energy from the sun ,doing work in achieving biological and other activities . the access energy is transmitted to the space. This system really represent a reversible thermal machine obey the 2nd law of thermodynamics and with efficiency about 56% . But the increase in the burning materials lead to an increase in the percentage of CO2 ,and since its molecules can absorb the radiation from the earth . thus leads to form irreversible engine with entropy production , by calculating the increase in CO2 the increase in entropy production is calculated . The increase in entropy increase earth’s temperature and lead to the greenhouse effect .

Key Words : Green house , Global otel for Green house, Atouspheric changes.