July 29, 2004
The Ministry of the Environment has compiled the results of ozone layer monitoring, covering the FY 2003 status of (i) ozone depletion, (ii) atmospheric chlorofluorocarbons (CFCs) concentrations, and (iii) solar ultraviolet radiation, pursuant to the Law concerning the Protection of the Ozone Layer through the Control of Specified Substances and Other Measures (hereinafter referred to as the "Ozone Layer Protection Law").
In order to disseminate information on the status of ozone depletion and its countermeasures to the general public, the Ministry published a brochure facilitating the monitoring results to understand in FY 2004.
1. State of the ozone layer
Global total ozone has been continuously lower level compared to that had been seen before the 1980's (an average volume between 1964 to 1980). A marked decline is noted in high latitudes in spring. In Japan, a long term decline is observed in Sapporo (Hokkaido), Tsukuba (Kanto area) and Kagoshima (Kyushu area). The decline is most prominent in Sapporo.
In 2003, the ozone hole over Antarctica grew earlier than previous years. The volume of depletion was all time high and the area marked the second largest. Recent observation shows that the growth of the ozone hole is slowing down, while continuously expanding on a long term basis, leaving the ozone layer in the Antarctica in critical condition.
2. State of atmospheric CFCs concentration
The concentration of CFC-12 has been remaining broadly unchanged since the latter half of the 1990s, and the concentrations of CFC-11 and -113 have been in decline. On the other hand, the concentrations of hydrochlorofluorocarbon (HCFC) and hydrofluorocarbon ( HFC ) have been in an upward trend.
Compared to the 1970s, recent atmospheric concentrations of specified ozone-depleting substances are at substantially high levels. In order to improve the state of the stratospheric ozone layer, concentrations of these substances need to be drastically reduced.
3. State of solar ultraviolet radiation
Each value of harmful ultraviolet rays (UV-B) obtained at Sapporo, Tsukuba, Kagoshima and Naha (Okinawa) has not shown any major changes since the observation started in 1991.
It has been confirmed that the UV-B radiation reaching the land surface will increase when total ozone is decreasing. Therefore, the volume of UV-B is deemed to have increased in the areas where total ozone had explicitly decreased compared to the 1970s.