Effect of Sea-level Rise on Japan

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Based on a study of the land mass, population and assets at risk as indicators, the impact of sea level rise was evaluated. Using different water levels - mean water, high water, high tide, and storm surge/tsunami - it was discovered that even at normal conditions, more than 861 sq.km. is below mean high water level. There are two million people who live in this zone, with 54 trillion yen assets.

If the sea level rises by 1 m, this zone will expand to 2,340 sq.km or 2.7 times larger. The affected population will be 4.1 million, and assets will be 109 trillion yen. Moreover, the flood prone area, which is currently 6,270 sq.km. will expand to 8,900 sq.km. if the sea-level rises 1 m. More than 15 million may be endangered.

Impact of Sea-Level Rise on Area, Population and Assets in Japan
Unit: Area (sq.km.), Population (thousands), Assets (trillion yen)

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	Present
	Area	Population	Assets
Mean Water level	364	1,020	34
High water level	861	2,000	54
High tide level (Storm surge or Tsunami)	6268	11,740	288

	0.3 m rise
	Area	Population	Assets
Mean Water level	411	1,140	37
High water level	1192	2,520	68
High tide level (Storm surge or Tsunami)	6662	12,300	302

	0.5m rise
	Area	Population	Assets
Mean Water level	521	1,400	44
High water level	1421	2,860	77
High tide level (Storm surge or Tsunami)	7583	13,580	333

	1.0 m rise
	Area	Population	Assets
Mean Water level	679	1,780	53
High water level	2339	4,100	109
High tide level (Storm surge or Tsunami)	8893	15,420	378

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Source: CGER, Data Book on Sea-Level Rise. Tokyo: Center for Global Environmental Research, Environment Agency of Japan, 1996, pp. 67-68.

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