NOVELTY - An earth environment improvement system carries out electrolysis of seawater to generate chlorine and hydrogen, and generation of methane gas and oxygen from obtained hydrogen and carbon dioxide in atmosphere. The methane gas is buried underground, and oxygen is discharged such that to restrain oxygen concentration decrease. The atmosphere heat is absorbed with heat of cooling "conservation of energy law" produced in generation processes.    USE - Earth environment improvement system.    ADVANTAGE - The earth environment improvement system increases oxygen concentration in atmosphere. The ozone layer depletion and global warming are prevented. The sea acidification is prevented by removing carbon oxide absorbed by seawater. The urban area and fertile farmland are protected from sea-level rise by global warming. The fish and shellfish are protected from sea acidification, and contributes to "marine biological organism protection", and "future food stability".    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following:    (1) seawater neutralization system, which carries out contact of obtained chlorine with alkaline seawater and generation of oxygen with neutralization of seawater;    (2) combination pipe (16), which has gradient in which light hydrogen and carbon dioxide contact slowly, a protrusion provided in upper portion and which allows hydrogen to pass through, and a hole provided in lower portion. The combination pipe has a structure which absorbs carbon dioxide in atmosphere using pressure reduction state produced by combination reaction;    (3) seawater improvement system, which utilizes tidal variation of tide to pressure-reduce seawater of high tide and remove carbon dioxide. The seawater in which sea acidification is carried out, is neutralized. The oxygen deficiency of seawater produced by pressure reduction is prevented, by mixing oxygen generated in "Claim 1" and "Claim 2" during drainage;    (4) vertical combination theory (conjecture) during methane gas production on Mars(sic);    (5) oxygen classification system, which carries out application of ultraviolet ray to oxygen and change oxygen to ozone. The heavy ozone is discharged; and    (6) methane gas production auxiliary theory (conjecture), which assists by ultraviolet ray, ultrasonic wave, vibration, etc. during methane gas production.    DESCRIPTION OF DRAWING(S) - The drawing shows the schematic view of the earth environment improvement system. (Drawing includes non-English language text)    Collection box (11)    Windless air (12)    Carbon dioxide inflow (14)    Combination pipe (16)    Sodium hydroxide solution (17)