water) in the shape of lens (freshwater lens), and this freshwater lens is pushed higher by the rise in sea level, thus lowering the quantity of freshwater available (Figure 4-1-5).

The long-term examination of annual precipitation in

Figure4-1-6 Changes in Deviation from the Normal Year in Annual Precipitation in Japan (1898-2008)

Note: The figure shows trends in annual precipitation at 51 locations in Japan. Bar graphs show deviation from the normal year (the percentage ratio to the normal year value) in annual precipitation in each year. The red line shows the five-year moving average in deviation from the normal year. The normal year value is the 30-year average for 1971-2000.

Source: Japan Meteorological Agency, 2009

## 3 Various Problems Caused by Water

Due to population growth, global warming and the growth of emerging economies (which means increased demand for industrial water), it is expected that “an additional 1.8 billion people could be living in a water scarce environment by 2080,” pointing to a very serious water situation in the world (Source: UNDP, “Human Development Report 2007/2008).

Japan reveals that there were periods of heavy rains until the mid-1920s and around the 1950s, and annual changes in precipitation have become larger year by year since the 1970s (Figure 4-1-6). Further, the number of days with daily precipitation of 100 millimeters or more has been on the significant rise in the long term, and comparison between the recent 30 years and the 30 years in the early 20th century shows a rise of about 1.2 times (Figure 4-1-7).

## 1 ) Uneven distribution of water resources and demand outlook

Figure4-1-7 Interannual Changes in the Annual Number of Days with Precipitation of 100mm or more (No. of days)

According to data provided by the Food and Agriculture Organization (FAO), there are big gaps in

## Column ▶ Deep Circulation in Oceans

Regarding deep circulation in oceans, the IPCC AR4 notes there is no sufficient evidence to determine where there are some tendencies in deep circulations, projecting that there is very little possibility of deep circulations showing large and rapid changes by the end of the 21 $ ^{st} $ century. On the other hand, the current model-based projection points to the very high possibility of deep circulation in the Atlantic Ocean weakening during the 21 $ ^{st} $ century.

Note: The annual number of days per location obtained from the number of days of incidence at 51 locations in Japan.

indicates the value for each year, while ∼ shows the 11-year moving average value.

Source: "Climate Change Monitoring Report 2009" (Japan Meteorological Agency, 2010)

per-capita annual water resources among countries, and the uneven distribution of water resources is evident, with countries with relatively small water resources having relatively large populations (Figure 4-1-8). The U.N. Educational, Scientific and Cultural Organization (UNESCO) forecast a substantial increase in demand for water in Asia going forward (Figure 4-1-9). While the global population is projected to rise by about 1.4 times during a 30-year period between 1995 and 2025, domestic noncommercial use of water and water for industrial use are both expected to show sharp rises of about 1.8 times and about 1.6 times, respectively, due to population growth (Figure 4-1-10). For water for agricultural use,