This paper describes possible reduction of CO2 emission from fossil fuels in the world. The reduction in this paper means that from the necessary fossil fuelconsumption in 2005 by saving energy with raising thermal efficiency. By raising thermal efficiency, human kind can possibly save energy in four sectors by about 30%;industry, transportation, electric power generation and consumption, and residential and commercial.
Since reduction of CO2 emission would also become about 30% in 2005, the total CO2 emission amount would be as same as that in 1986; the total CO2 emission amount would be kept almost constant in coming 15 years.
One of the other possible countermeasures would be forestation of the destructed forests or of the dry area. Annual forestation of about 0.4 million km2 would make required forest area to absorb CO2 to reduce CO2 emission by 50% in 20 years.
