browse the latest conversion formulas 10 a 10 b posted on line for calculating the emission index of greenhouse effect gases determined by the ipcc 14 and the values of coefficients used in these conversion formulas 10 a 10 b conversion programs 10 a 10 b are compiled for executing a calculation of emission index of greenhouse effect gases on the basis of the conversion formulas 10 a 10 b revised by the ipcc 14 by the operation processing unit 10 and these conversion programs 10 a 10 b are distributed as conversion information to each greenhouse effect gas emission index converter 2 through the internet u2122 6 therefore when each greenhouse effect gas emission index converter 2 executes a specified program among the conversion programs 10 a 10 b received from the conversion information supply terminal 7 the emission index of greenhouse effect gases for example carbon equivalent m using a common conversion formula can be calculated and it can be displayed in the display unit 13 further each greenhouse effect gas emission index converter 2 issues the emission index m of greenhouse effect gases through the information output unit 11 so that a greenhouse effect gas emissions rights can be traded with other greenhouse effect gas emission index converters at that time a trade market unit 7 may be created to act as a clearinghouse for such trade in the configuration of this example the conversion formulas 10 a for calculating the emission index of greenhouse effect gases can be changed in batch by an instruction from the conversion information supply terminal 7 or by using an adjusted conversion formula so that the emission index of greenhouse effect gases can be obtained very easily that is the conversion formula of emission index of greenhouse effect gases.