Global problems have been raised by the fact of an environmental warming due to the green house effect of an increased carbon dioxide (CO₂) and basic researches have been under conducting by many countries' laboratories including the governmental authorities with an international cooperation. In the near future international agreement for the regulations against worldwide CO₂ emission is expected to be discussed. In this papers CO₂ recovered from the fossil fuel was taken up as the most influential gas quantitatively, and discussed the disposal of the solid CO₂ (SCO₂) into the deep ocean thermo-physically utilizing the vast storage capacity of CO₂ dissolution in the deep ocean. Spherical solid CO₂ is disposed into the sea water allowing a free settling with sublimation and melting from SCO₂ in a water.Settling velocity of CO₂ and heat transfer coefficient between SCO₂ and water was obtained taking a transpiration effect and mass reduction effect into consideration from empirical data. After landing on a sea bottom surfacial melting will occur and diffusion follows it in a sea water having a steady horizontal velocity. Melting and transient diffusion processes were calculated as a thermal and diffusion problem with an hypothetical eddy diffusion coefficient and water velocities. As conclusions viewing from a thermo-physical analysis a certain amount of SCO₂ will sublimate and melt during settling toward sea bottom, most of it, however, remain unmelt and reach on the sea bottom. Following diffusion are so rapid that a high concentration area of CO₂ will be so limited and within a short period of time.